Posts Tagged Prometheus

Istio Observability with Go, gRPC, and Protocol Buffers-based Microservices on Google Kubernetes Engine (GKE)

Posted by Gary A. Stafford in Bash Scripting, Build Automation, Client-Side Development, Cloud, Continuous Delivery, DevOps, Enterprise Software Development, GCP, Go, JavaScript, Kubernetes, Software Development on April 17, 2019

In the last two posts, Kubernetes-based Microservice Observability with Istio Service Mesh and Azure Kubernetes Service (AKS) Observability with Istio Service Mesh, we explored the observability tools which are included with Istio Service Mesh. These tools currently include Prometheus and Grafana for metric collection, monitoring, and alerting, Jaeger for distributed tracing, and Kiali for Istio service-mesh-based microservice visualization and monitoring. Combined with cloud platform-native monitoring and logging services, such as Stackdriver on GCP, CloudWatch on AWS, Azure Monitor logs on Azure, and we have a complete observability solution for modern, distributed, Cloud-based applications.

In this post, we will examine the use of Istio’s observability tools to monitor Go-based microservices that use Protocol Buffers (aka Protobuf) over gRPC (gRPC Remote Procedure Calls) and HTTP/2 for client-server communications, as opposed to the more traditional, REST-based JSON (JavaScript Object Notation) over HTTP (Hypertext Transfer Protocol). We will see how Kubernetes, Istio, Envoy, and the observability tools work seamlessly with gRPC, just as they do with JSON over HTTP, on Google Kubernetes Engine (GKE).

Technologies

gRPC

According to the gRPC project, gRPC, a CNCF incubating project, is a modern, high-performance, open-source and universal remote procedure call (RPC) framework that can run anywhere. It enables client and server applications to communicate transparently and makes it easier to build connected systems. Google, the original developer of gRPC, has used the underlying technologies and concepts in gRPC for years. The current implementation is used in several Google cloud products and Google externally facing APIs. It is also being used by Square, Netflix, CoreOS, Docker, CockroachDB, Cisco, Juniper Networks and many other organizations.

Protocol Buffers

By default, gRPC uses Protocol Buffers. According to Google, Protocol Buffers (aka Protobuf) are a language- and platform-neutral, efficient, extensible, automated mechanism for serializing structured data for use in communications protocols, data storage, and more. Protocol Buffers are 3 to 10 times smaller and 20 to 100 times faster than XML. Once you have defined your messages, you run the protocol buffer compiler for your application’s language on your .proto file to generate data access classes.

Protocol Buffers are 3 to 10 times smaller and 20 to 100 times faster than XML.

Protocol buffers currently support generated code in Java, Python, Objective-C, and C++, Dart, Go, Ruby, and C#. For this post, we have compiled for Go. You can read more about the binary wire format of Protobuf on Google’s Developers Portal.

Envoy Proxy

According to the Istio project, Istio uses an extended version of the Envoy proxy. Envoy is deployed as a sidecar to a relevant service in the same Kubernetes pod. Envoy, created by Lyft, is a high-performance proxy developed in C++ to mediate all inbound and outbound traffic for all services in the service mesh. Istio leverages Envoy’s many built-in features, including dynamic service discovery, load balancing, TLS termination, HTTP/2 and gRPC proxies, circuit-breakers, health checks, staged rollouts, fault injection, and rich metrics.

According to the post by Harvey Tuch of Google, Evolving a Protocol Buffer canonical API, Envoy proxy adopted Protocol Buffers, specifically proto3, as the canonical specification of for version 2 of Lyft’s gRPC-first API.

Reference Microservices Platform

In the last two posts, we explored Istio’s observability tools, using a RESTful microservices-based API platform written in Go and using JSON over HTTP for service to service communications. The API platform was comprised of eight Go-based microservices and one sample Angular 7, TypeScript-based front-end web client. The various services are dependent on MongoDB, and RabbitMQ for event queue-based communications. Below, the is JSON over HTTP-based platform architecture.

Below, the current Angular 7-based web client interface.

Converting to gRPC and Protocol Buffers

For this post, I have modified the eight Go microservices to use gRPC and Protocol Buffers, Google’s data interchange format. Specifically, the services use version 3 release (aka proto3) of Protocol Buffers. With gRPC, a gRPC client calls a gRPC server. Some of the platform’s services are gRPC servers, others are gRPC clients, while some act as both client and server, such as Service A, B, and E. The revised architecture is shown below.

gRPC Gateway

Assuming for the sake of this demonstration, that most consumers of the API would still expect to communicate using a RESTful JSON over HTTP API, I have added a gRPC Gateway reverse proxy to the platform. The gRPC Gateway is a gRPC to JSON reverse proxy, a common architectural pattern, which proxies communications between the JSON over HTTP-based clients and the gRPC-based microservices. A diagram from the grpc-gateway GitHub project site effectively demonstrates how the reverse proxy works.

Image courtesy: https://github.com/grpc-ecosystem/grpc-gateway

In the revised platform architecture diagram above, note the addition of the reverse proxy, which replaces Service A at the edge of the API. The proxy sits between the Angular-based Web UI and Service A. Also, note the communication method between services is now Protobuf over gRPC instead of JSON over HTTP. The use of Envoy Proxy (via Istio) is unchanged, as is the MongoDB Atlas-based databases and CloudAMQP RabbitMQ-based queue, which are still external to the Kubernetes cluster.

Alternatives to gRPC Gateway

As an alternative to the gRPC Gateway reverse proxy, we could convert the TypeScript-based Angular UI client to gRPC and Protocol Buffers, and continue to communicate directly with Service A as the edge service. However, this would limit other consumers of the API to rely on gRPC as opposed to JSON over HTTP, unless we also chose to expose two different endpoints, gRPC, and JSON over HTTP, another common pattern.

Demonstration

In this post’s demonstration, we will repeat the exact same installation process, outlined in the previous post, Kubernetes-based Microservice Observability with Istio Service Mesh. We will deploy the revised gRPC-based platform to GKE on GCP. You could just as easily follow Azure Kubernetes Service (AKS) Observability with Istio Service Mesh, and deploy the platform to AKS.

Source Code

All source code for this post is available on GitHub, contained in three projects. The Go-based microservices source code, all Kubernetes resources, and all deployment scripts are located in the k8s-istio-observe-backend project repository, in the new grpc branch.

git clone \
  --branch grpc --single-branch --depth 1 --no-tags \
  https://github.com/garystafford/k8s-istio-observe-backend.git

The Angular-based web client source code is located in the k8s-istio-observe-frontend repository on the new grpc branch. The source protocol buffers .proto file and the generated code, using the protocol buffers compiler, is located in the new pb-greeting project repository. You do not need to clone either of these projects for this post’s demonstration.

All Docker images for the services, UI, and the reverse proxy are located on Docker Hub.

Code Changes

This post is not specifically about writing Go for gRPC and Protobuf. However, to better understand the observability requirements and capabilities of these technologies, compared to JSON over HTTP, it is helpful to review some of the source code.

Service A

First, compare the source code for Service A, shown below, to the original code in the previous post. The service’s code is almost completely re-written. I relied on several references for writing the code, including, Tracing gRPC with Istio, written by Neeraj Poddar of Aspen Mesh and Distributed Tracing Infrastructure with Jaeger on Kubernetes, by Masroor Hasan.

Specifically, note the following code changes to Service A:

Import of the pb-greeting protobuf package;
Local Greeting struct replaced with pb.Greeting struct;
All services are now hosted on port 50051;
The HTTP server and all API resource handler functions are removed;
Headers, used for distributed tracing with Jaeger, have moved from HTTP request object to metadata passed in the gRPC context object;
Service A is coded as a gRPC server, which is called by the gRPC Gateway reverse proxy (gRPC client) via the Greeting function;
The primary PingHandler function, which returns the service’s Greeting, is replaced by the pb-greeting protobuf package’s Greeting function;
Service A is coded as a gRPC client, calling both Service B and Service C using the CallGrpcService function;
CORS handling is offloaded to Istio;
Logging methods are unchanged;

Source code for revised gRPC-based Service A (gist):

	// author: Gary A. Stafford
	// site: https://programmaticponderings.com
	// license: MIT License
	// purpose: Service A – gRPC/Protobuf

	package main

	import (
	"context"
	"github.com/banzaicloud/logrus-runtime-formatter"
	"github.com/google/uuid"
	"github.com/grpc-ecosystem/go-grpc-middleware/tracing/opentracing"
	ot "github.com/opentracing/opentracing-go"
	log "github.com/sirupsen/logrus"
	"google.golang.org/grpc"
	"google.golang.org/grpc/metadata"
	"net"
	"os"
	"time"

	pb "github.com/garystafford/pb-greeting"
	)

	const (
	port = ":50051"
	)

	type greetingServiceServer struct {
	}

	var (
	greetings []*pb.Greeting
	)

	func (s greetingServiceServer) Greeting(ctx context.Context, req pb.GreetingRequest) (*pb.GreetingResponse, error) {
	greetings = nil

	tmpGreeting := pb.Greeting{
	Id: uuid.New().String(),
	Service: "Service-A",
	Message: "Hello, from Service-A!",
	Created: time.Now().Local().String(),
	}

	greetings = append(greetings, &tmpGreeting)

	CallGrpcService(ctx, "service-b:50051")
	CallGrpcService(ctx, "service-c:50051")

	return &pb.GreetingResponse{
	Greeting: greetings,
	}, nil
	}

	func CallGrpcService(ctx context.Context, address string) {
	conn, err := createGRPCConn(ctx, address)
	if err != nil {
	log.Fatalf("did not connect: %v", err)
	}
	defer conn.Close()

	headersIn, _ := metadata.FromIncomingContext(ctx)
	log.Infof("headersIn: %s", headersIn)

	client := pb.NewGreetingServiceClient(conn)
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)

	ctx = metadata.NewOutgoingContext(context.Background(), headersIn)

	defer cancel()

	req := pb.GreetingRequest{}
	greeting, err := client.Greeting(ctx, &req)
	log.Info(greeting.GetGreeting())
	if err != nil {
	log.Fatalf("did not connect: %v", err)
	}

	for _, greeting := range greeting.GetGreeting() {
	greetings = append(greetings, greeting)
	}
	}

	func createGRPCConn(ctx context.Context, addr string) (*grpc.ClientConn, error) {
	//https://aspenmesh.io/2018/04/tracing-grpc-with-istio/
	var opts []grpc.DialOption
	opts = append(opts, grpc.WithStreamInterceptor(
	grpc_opentracing.StreamClientInterceptor(
	grpc_opentracing.WithTracer(ot.GlobalTracer()))))
	opts = append(opts, grpc.WithUnaryInterceptor(
	grpc_opentracing.UnaryClientInterceptor(
	grpc_opentracing.WithTracer(ot.GlobalTracer()))))
	opts = append(opts, grpc.WithInsecure())
	conn, err := grpc.DialContext(ctx, addr, opts…)
	if err != nil {
	log.Fatalf("Failed to connect to application addr: ", err)
	return nil, err
	}
	return conn, nil
	}

	func getEnv(key, fallback string) string {
	if value, ok := os.LookupEnv(key); ok {
	return value
	}
	return fallback
	}

	func init() {
	formatter := runtime.Formatter{ChildFormatter: &log.JSONFormatter{}}
	formatter.Line = true
	log.SetFormatter(&formatter)
	log.SetOutput(os.Stdout)
	level, err := log.ParseLevel(getEnv("LOG_LEVEL", "info"))
	if err != nil {
	log.Error(err)
	}
	log.SetLevel(level)
	}

	func main() {
	lis, err := net.Listen("tcp", port)
	if err != nil {
	log.Fatalf("failed to listen: %v", err)
	}

	s := grpc.NewServer()
	pb.RegisterGreetingServiceServer(s, &greetingServiceServer{})
	log.Fatal(s.Serve(lis))
	}

view raw

main.go

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Greeting Protocol Buffers

Shown below is the greeting source protocol buffers .proto file. The greeting response struct, originally defined in the services, remains largely unchanged (gist). The UI client responses will look identical.

	syntax = "proto3";
	package greeting;

	import "google/api/annotations.proto";

	message Greeting {
	string id = 1;
	string service = 2;
	string message = 3;
	string created = 4;
	}


	message GreetingRequest {
	}

	message GreetingResponse {
	repeated Greeting greeting = 1;
	}

	service GreetingService {
	rpc Greeting (GreetingRequest) returns (GreetingResponse) {
	option (google.api.http) = {
	get: "/api/v1/greeting"
	};
	}
	}

view raw

greeting.proto

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When compiled with protoc, the Go-based protocol compiler plugin, the original 27 lines of source code swells to almost 270 lines of generated data access classes that are easier to use programmatically.

# Generate gRPC stub (.pb.go)
protoc -I /usr/local/include -I. \
  -I ${GOPATH}/src \
  -I ${GOPATH}/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
  --go_out=plugins=grpc:. \
  greeting.proto

# Generate reverse-proxy (.pb.gw.go)
protoc -I /usr/local/include -I. \
  -I ${GOPATH}/src \
  -I ${GOPATH}/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
  --grpc-gateway_out=logtostderr=true:. \
  greeting.proto

# Generate swagger definitions (.swagger.json)
protoc -I /usr/local/include -I. \
  -I ${GOPATH}/src \
  -I ${GOPATH}/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
  --swagger_out=logtostderr=true:. \
  greeting.proto

Below is a small snippet of that compiled code, for reference. The compiled code is included in the pb-greeting project on GitHub and imported into each microservice and the reverse proxy (gist). We also compile a separate version for the reverse proxy to implement.

	// Code generated by protoc-gen-go. DO NOT EDIT.
	// source: greeting.proto

	package greeting

	import (
	context "context"
	fmt "fmt"
	proto "github.com/golang/protobuf/proto"
	_ "google.golang.org/genproto/googleapis/api/annotations"
	grpc "google.golang.org/grpc"
	codes "google.golang.org/grpc/codes"
	status "google.golang.org/grpc/status"
	math "math"
	)

	// Reference imports to suppress errors if they are not otherwise used.
	var _ = proto.Marshal
	var _ = fmt.Errorf
	var _ = math.Inf

	// This is a compile-time assertion to ensure that this generated file
	// is compatible with the proto package it is being compiled against.
	// A compilation error at this line likely means your copy of the
	// proto package needs to be updated.
	const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package

	type Greeting struct {
	Id string `protobuf:"bytes,1,opt,name=id,proto3" json:"id,omitempty"`
	Service string `protobuf:"bytes,2,opt,name=service,proto3" json:"service,omitempty"`
	Message string `protobuf:"bytes,3,opt,name=message,proto3" json:"message,omitempty"`
	Created string `protobuf:"bytes,4,opt,name=created,proto3" json:"created,omitempty"`
	XXX_NoUnkeyedLiteral struct{} `json:"-"`
	XXX_unrecognized []byte `json:"-"`
	XXX_sizecache int32 `json:"-"`
	}

	func (m Greeting) Reset() { m = Greeting{} }
	func (m *Greeting) String() string { return proto.CompactTextString(m) }
	func (*Greeting) ProtoMessage() {}
	func (*Greeting) Descriptor() ([]byte, []int) {
	return fileDescriptor_6acac03ccd168a87, []int{0}
	}

	func (m *Greeting) XXX_Unmarshal(b []byte) error {
	return xxx_messageInfo_Greeting.Unmarshal(m, b)
	}
	func (m *Greeting) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
	return xxx_messageInfo_Greeting.Marshal(b, m, deterministic)

view raw

greeting.pb.go

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Using Swagger, we can view the greeting protocol buffers’ single RESTful API resource, exposed with an HTTP GET method. I use the Docker-based version of Swagger UI for viewing protoc generated swagger definitions.

docker run -p 8080:8080 -d --name swagger-ui \
  -e SWAGGER_JSON=/tmp/greeting.swagger.json \
  -v ${GOAPTH}/src/pb-greeting:/tmp swaggerapi/swagger-ui

The Angular UI makes an HTTP GET request to the /api/v1/greeting resource, which is transformed to gRPC and proxied to Service A, where it is handled by the Greeting function.

gRPC Gateway Reverse Proxy

As explained earlier, the gRPC Gateway reverse proxy service is completely new. Specifically, note the following code features in the gist below:

Import of the pb-greeting protobuf package;
The proxy is hosted on port 80;
Request headers, used for distributed tracing with Jaeger, are collected from the incoming HTTP request and passed to Service A in the gRPC context;
The proxy is coded as a gRPC client, which calls Service A;
Logging is largely unchanged;

The source code for the Reverse Proxy (gist):

	// author: Gary A. Stafford
	// site: https://programmaticponderings.com
	// license: MIT License
	// purpose: gRPC Gateway / Reverse Proxy
	// reference: https://github.com/grpc-ecosystem/grpc-gateway

	package main

	import (
	"context"
	"flag"
	lrf "github.com/banzaicloud/logrus-runtime-formatter"
	gw "github.com/garystafford/pb-greeting"
	"github.com/grpc-ecosystem/grpc-gateway/runtime"
	log "github.com/sirupsen/logrus"
	"google.golang.org/grpc"
	"google.golang.org/grpc/metadata"
	"net/http"
	"os"
	)

	func injectHeadersIntoMetadata(ctx context.Context, req *http.Request) metadata.MD {
	//https://aspenmesh.io/2018/04/tracing-grpc-with-istio/
	var (
	otHeaders = []string{
	"x-request-id",
	"x-b3-traceid",
	"x-b3-spanid",
	"x-b3-parentspanid",
	"x-b3-sampled",
	"x-b3-flags",
	"x-ot-span-context"}
	)
	var pairs []string

	for _, h := range otHeaders {
	if v := req.Header.Get(h); len(v) > 0 {
	pairs = append(pairs, h, v)
	}
	}
	return metadata.Pairs(pairs…)
	}

	type annotator func(context.Context, *http.Request) metadata.MD

	func chainGrpcAnnotators(annotators …annotator) annotator {
	return func(c context.Context, r *http.Request) metadata.MD {
	var mds []metadata.MD
	for _, a := range annotators {
	mds = append(mds, a(c, r))
	}
	return metadata.Join(mds…)
	}
	}

	func run() error {
	ctx := context.Background()
	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	annotators := []annotator{injectHeadersIntoMetadata}

	mux := runtime.NewServeMux(
	runtime.WithMetadata(chainGrpcAnnotators(annotators…)),
	)

	opts := []grpc.DialOption{grpc.WithInsecure()}
	err := gw.RegisterGreetingServiceHandlerFromEndpoint(ctx, mux, "service-a:50051", opts)
	if err != nil {
	return err
	}

	return http.ListenAndServe(":80", mux)
	}

	func getEnv(key, fallback string) string {
	if value, ok := os.LookupEnv(key); ok {
	return value
	}
	return fallback
	}

	func init() {
	formatter := lrf.Formatter{ChildFormatter: &log.JSONFormatter{}}
	formatter.Line = true
	log.SetFormatter(&formatter)
	log.SetOutput(os.Stdout)
	level, err := log.ParseLevel(getEnv("LOG_LEVEL", "info"))
	if err != nil {
	log.Error(err)
	}
	log.SetLevel(level)
	}

	func main() {
	flag.Parse()

	if err := run(); err != nil {
	log.Fatal(err)
	}
	}

view raw

main.go

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Below, in the Stackdriver logs, we see an example of a set of HTTP request headers in the JSON payload, which are propagated upstream to gRPC-based Go services from the gRPC Gateway’s reverse proxy. Header propagation ensures the request produces a complete distributed trace across the complete service call chain.

Istio VirtualService and CORS

According to feedback in the project’s GitHub Issues, the gRPC Gateway does not directly support Cross-Origin Resource Sharing (CORS) policy. In my own experience, the gRPC Gateway cannot handle OPTIONS HTTP method requests, which must be issued by the Angular 7 web UI. Therefore, I have offloaded CORS responsibility to Istio, using the VirtualService resource’s CorsPolicy configuration. This makes CORS much easier to manage than coding CORS configuration into service code (gist):

	apiVersion: networking.istio.io/v1alpha3
	kind: VirtualService
	metadata:
	name: service-rev-proxy
	spec:
	hosts:
	– api.dev.example-api.com
	gateways:
	– demo-gateway
	http:
	– match:
	– uri:
	prefix: /
	route:
	– destination:
	port:
	number: 80
	host: service-rev-proxy.dev.svc.cluster.local
	weight: 100
	corsPolicy:
	allowOrigin:
	– "*"
	allowMethods:
	– OPTIONS
	– GET
	allowCredentials: true
	allowHeaders:
	– "*"

view raw

istio-gateway.yaml

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Set-up and Installation

To deploy the microservices platform to GKE, follow the detailed instructions in part one of the post, Kubernetes-based Microservice Observability with Istio Service Mesh: Part 1, or Azure Kubernetes Service (AKS) Observability with Istio Service Mesh for AKS.

Create the external MongoDB Atlas database and CloudAMQP RabbitMQ clusters;
Modify the Kubernetes resource files and bash scripts for your own environments;
Create the managed GKE or AKS cluster on GCP or Azure;
Configure and deploy Istio to the managed Kubernetes cluster, using Helm;
Create DNS records for the platform’s exposed resources;
Deploy the Go-based microservices, gRPC Gateway reverse proxy, Angular UI, and associated resources to Kubernetes cluster;
Test and troubleshoot the platform deployment;
Observe the results;

The Three Pillars

As introduced in the first post, logs, metrics, and traces are often known as the three pillars of observability. These are the external outputs of the system, which we may observe. As modern distributed systems grow ever more complex, the ability to observe those systems demands equally modern tooling that was designed with this level of complexity in mind. Traditional logging and monitoring systems often struggle with today’s hybrid and multi-cloud, polyglot language-based, event-driven, container-based and serverless, infinitely-scalable, ephemeral-compute platforms.

Tools like Istio Service Mesh attempt to solve the observability challenge by offering native integrations with several best-of-breed, open-source telemetry tools. Istio’s integrations include Jaeger for distributed tracing, Kiali for Istio service mesh-based microservice visualization and monitoring, and Prometheus and Grafana for metric collection, monitoring, and alerting. Combined with cloud platform-native monitoring and logging services, such as Stackdriver for GKE, CloudWatch for Amazon’s EKS, or Azure Monitor logs for AKS, and we have a complete observability solution for modern, distributed, Cloud-based applications.

Pillar 1: Logging

Moving from JSON over HTTP to gRPC does not require any changes to the logging configuration of the Go-based service code or Kubernetes resources.

Stackdriver with Logrus

As detailed in part two of the last post, Kubernetes-based Microservice Observability with Istio Service Mesh, our logging strategy for the eight Go-based microservices and the reverse proxy continues to be the use of Logrus, the popular structured logger for Go, and Banzai Cloud’s logrus-runtime-formatter.

If you recall, the Banzai formatter automatically tags log messages with runtime/stack information, including function name and line number; extremely helpful when troubleshooting. We are also using Logrus’ JSON formatter. Below, in the Stackdriver console, note how each log entry below has the JSON payload contained within the message with the log level, function name, lines on which the log entry originated, and the message.

Below, we see the details of a specific log entry’s JSON payload. In this case, we can see the request headers propagated from the downstream service.

Pillar 2: Metrics

Moving from JSON over HTTP to gRPC does not require any changes to the metrics configuration of the Go-based service code or Kubernetes resources.

Prometheus

Prometheus is a completely open source and community-driven systems monitoring and alerting toolkit originally built at SoundCloud, circa 2012. Interestingly, Prometheus joined the Cloud Native Computing Foundation (CNCF) in 2016 as the second hosted-project, after Kubernetes.

Grafana

Grafana describes itself as the leading open source software for time series analytics. According to Grafana Labs, Grafana allows you to query, visualize, alert on, and understand your metrics no matter where they are stored. You can easily create, explore, and share visually-rich, data-driven dashboards. Grafana allows users to visually define alert rules for your most important metrics. Grafana will continuously evaluate rules and can send notifications.

According to Istio, the Grafana add-on is a pre-configured instance of Grafana. The Grafana Docker base image has been modified to start with both a Prometheus data source and the Istio Dashboard installed. Below, we see two of the pre-configured dashboards, the Istio Mesh Dashboard and the Istio Performance Dashboard.

Pillar 3: Traces

Moving from JSON over HTTP to gRPC did require a complete re-write of the tracing logic in the service code. In fact, I spent the majority of my time ensuring the correct headers were propagated from the Istio Ingress Gateway to the gRPC Gateway reverse proxy, to Service A in the gRPC context, and upstream to all the dependent, gRPC-based services. I am sure there are a number of optimization in my current code, regarding the correct handling of traces and how this information is propagated across the service call stack.

Jaeger

According to their website, Jaeger, inspired by Dapper and OpenZipkin, is a distributed tracing system released as open source by Uber Technologies. It is used for monitoring and troubleshooting microservices-based distributed systems, including distributed context propagation, distributed transaction monitoring, root cause analysis, service dependency analysis, and performance and latency optimization. The Jaeger website contains an excellent overview of Jaeger’s architecture and general tracing-related terminology.

Below we see the Jaeger UI Traces View. In it, we see a series of traces generated by hey, a modern load generator and benchmarking tool, and a worthy replacement for Apache Bench (ab). Unlike ab, hey supports HTTP/2. The use of hey was detailed in the previous post.

A trace, as you might recall, is an execution path through the system and can be thought of as a directed acyclic graph (DAG) of spans. If you have worked with systems like Apache Spark, you are probably already familiar with DAGs.

Below we see the Jaeger UI Trace Detail View. The example trace contains 16 spans, which encompasses nine components – seven of the eight Go-based services, the reverse proxy, and the Istio Ingress Gateway. The trace and the spans each have timings. The root span in the trace is the Istio Ingress Gateway. In this demo, traces do not span the RabbitMQ message queues. This means you would not see a trace which includes the decoupled, message-based communications between Service D to Service F, via the RabbitMQ.

Within the Jaeger UI Trace Detail View, you also have the ability to drill into a single span, which contains additional metadata. Metadata includes the URL being called, HTTP method, response status, and several other headers.

Microservice Observability

Moving from JSON over HTTP to gRPC does not require any changes to the Kiali configuration of the Go-based service code or Kubernetes resources.

Kiali

According to their website, Kiali provides answers to the questions: What are the microservices in my Istio service mesh, and how are they connected? Kiali works with Istio, in OpenShift or Kubernetes, to visualize the service mesh topology, to provide visibility into features like circuit breakers, request rates and more. It offers insights about the mesh components at different levels, from abstract Applications to Services and Workloads.

The Graph View in the Kiali UI is a visual representation of the components running in the Istio service mesh. Below, filtering on the cluster’s dev Namespace, we should observe that Kiali has mapped all components in the platform, along with rich metadata, such as their version and communication protocols.

Using Kiali, we can confirm our service-to-service IPC protocol is now gRPC instead of the previous HTTP.

Conclusion

Although converting from JSON over HTTP to protocol buffers with gRPC required major code changes to the services, it did not impact the high-level observability we have of those services using the tools provided by Istio, including Prometheus, Grafana, Jaeger, and Kiali.

All opinions expressed in this post are my own and not necessarily the views of my current or past employers or their clients.

AKS, API, GCP, GKE, Go, Golang, Grafana, gRPC, Istio, Jaeger, Kiali, Logging, Microservices, Observability, Prometheus, Protobuf, Protocol Buffers, Service Mesh

2 Comments

Azure Kubernetes Service (AKS) Observability with Istio Service Mesh

Posted by Gary A. Stafford in Azure, Bash Scripting, Cloud, DevOps, Go, JavaScript, Kubernetes, Software Development on March 31, 2019

In the last two-part post, Kubernetes-based Microservice Observability with Istio Service Mesh, we deployed Istio, along with its observability tools, Prometheus, Grafana, Jaeger, and Kiali, to Google Kubernetes Engine (GKE). Following that post, I received several questions about using Istio’s observability tools with other popular managed Kubernetes platforms, primarily Azure Kubernetes Service (AKS). In most cases, including with AKS, both Istio and the observability tools are compatible.

In this short follow-up of the last post, we will replace the GKE-specific cluster setup commands, found in part one of the last post, with new commands to provision a similar AKS cluster on Azure. The new AKS cluster will run Istio 1.1.3, released 4/15/2019, alongside the latest available version of AKS (Kubernetes), 1.12.6. We will replace Google’s Stackdriver logging with Azure Monitor logs. We will retain the external MongoDB Atlas cluster and the external CloudAMQP cluster dependencies.

Previous articles about AKS include First Impressions of AKS, Azure’s New Managed Kubernetes Container Service (November 2017) and Architecting Cloud-Optimized Apps with AKS (Azure’s Managed Kubernetes), Azure Service Bus, and Cosmos DB (December 2017).

Source Code

git clone \
  --branch master --single-branch \
  --depth 1 --no-tags \
  https://github.com/garystafford/k8s-istio-observe-backend.git

The Angular UI TypeScript-based source code is located in the k8s-istio-observe-frontend repository. You will not need to clone the Angular UI project for this post’s demonstration.

Setup

This post assumes you have a Microsoft Azure account with the necessary resource providers registered, and the Azure Command-Line Interface (CLI), az, installed and available to your command shell. You will also need Helm and Istio 1.1.3 installed and configured, which is covered in the last post.

Start by logging into Azure from your command shell.

az login \
  --username {{ your_username_here }} \
  --password {{ your_password_here }}

Resource Providers

If you are new to Azure or AKS, you may need to register some additional resource providers to complete this demonstration.

az provider list --output table

If you are missing required resource providers, you will see errors similar to the one shown below. Simply activate the particular provider corresponding to the error.

Operation failed with status:'Bad Request'. 
Details: Required resource provider registrations 
Microsoft.Compute, Microsoft.Network are missing.

To register the necessary providers, use the Azure CLI or the Azure Portal UI.

az provider register --namespace Microsoft.ContainerService
az provider register --namespace Microsoft.Network
az provider register --namespace Microsoft.Compute

Resource Group

AKS requires an Azure Resource Group. According to Azure, a resource group is a container that holds related resources for an Azure solution. The resource group includes those resources that you want to manage as a group. I chose to create a new resource group associated with my closest geographic Azure Region, East US, using the Azure CLI.

az group create \
  --resource-group aks-observability-demo \
  --location eastus

Create the AKS Cluster

Before creating the GKE cluster, check for the latest versions of AKS. At the time of this post, the latest versions of AKS was 1.12.6.

az aks get-versions \
  --location eastus \
  --output table

Using the latest GKE version, create the GKE managed cluster. There are many configuration options available with the az aks create command. For this post, I am creating three worker nodes using the Azure Standard_DS3_v2 VM type, which will give us a total of 12 vCPUs and 42 GB of memory. Anything smaller and all the Pods may not be schedulable. Instead of supplying an existing SSH key, I will let Azure create a new one. You should have no need to SSH into the worker nodes. I am also enabling the monitoring add-on. According to Azure, the add-on sets up Azure Monitor for containers, announced in December 2018, which monitors the performance of workloads deployed to Kubernetes environments hosted on AKS.

time az aks create \
  --name aks-observability-demo \
  --resource-group aks-observability-demo \
  --node-count 3 \
  --node-vm-size Standard_DS3_v2 \
  --enable-addons monitoring \
  --generate-ssh-keys \
  --kubernetes-version 1.12.6

Using the time command, we observe that the cluster took approximately 5m48s to provision; I have seen times up to almost 10 minutes. AKS provisioning is not as fast as GKE, which in my experience is at least 2x-3x faster than AKS for a similarly sized cluster.

After the cluster creation completes, retrieve your AKS cluster credentials.

az aks get-credentials \
  --name aks-observability-demo \
  --resource-group aks-observability-demo \
  --overwrite-existing

Examine the Cluster

Use the following command to confirm the cluster is ready by examining the status of three worker nodes.

kubectl get nodes --output=wide

Observe that Azure currently uses Ubuntu 16.04.5 LTS for the worker node’s host operating system. If you recall, GKE offers both Ubuntu as well as a Container-Optimized OS from Google.

Kubernetes Dashboard

Unlike GKE, there is no custom AKS dashboard. Therefore, we will use the Kubernetes Web UI (dashboard), which is installed by default with AKS, unlike GKE. According to Azure, to make full use of the dashboard, since the AKS cluster uses RBAC, a ClusterRoleBinding must be created before you can correctly access the dashboard.

kubectl create clusterrolebinding kubernetes-dashboard \
  --clusterrole=cluster-admin \
  --serviceaccount=kube-system:kubernetes-dashboard

Next, we must create a proxy tunnel on local port 8001 to the dashboard running on the AKS cluster. This CLI command creates a proxy between your local system and the Kubernetes API and opens your web browser to the Kubernetes dashboard.

az aks browse \
  --name aks-observability-demo \
  --resource-group aks-observability-demo

Although you should use the Azure CLI, PowerShell, or SDK for all your AKS configuration tasks, using the dashboard for monitoring the cluster and the resources running on it, is invaluable.

The Kubernetes dashboard also provides access to raw container logs. Azure Monitor provides the ability to construct complex log queries, but for quick troubleshooting, you may just want to see the raw logs a specific container is outputting, from the dashboard.

Azure Portal

Logging into the Azure Portal, we can observe the AKS cluster, within the new Resource Group.

In addition to the Azure Resource Group we created, there will be a second Resource Group created automatically during the creation of the AKS cluster. This group contains all the resources that compose the AKS cluster. These resources include the three worker node VM instances, and their corresponding storage disks and NICs. The group also includes a network security group, route table, virtual network, and an availability set.

Deploy Istio

From this point on, the process to deploy Istio Service Mesh and the Go-based microservices platform follows the previous post and use the exact same scripts. After modifying the Kubernetes resource files, to deploy Istio, use the bash script, part4_install_istio.sh. I have added a few more pauses in the script to account for the apparently slower response times from AKS as opposed to GKE. It definitely takes longer to spin up the Istio resources on AKS than on GKE, which can result in errors if you do not pause between each stage of the deployment process.

Using the Kubernetes dashboard, we can view the Istio resources running in the istio-system Namespace, as shown below. Confirm that all resource Pods are running and healthy before deploying the Go-based microservices platform.

Deploy the Platform

Deploy the Go-based microservices platform, using bash deploy script, part5a_deploy_resources.sh.

The script deploys two replicas (Pods) of each of the eight microservices, Service-A through Service-H, and the Angular UI, to the dev and test Namespaces, for a total of 36 Pods. Each Pod will have the Istio sidecar proxy (Envoy Proxy) injected into it, alongside the microservice or UI.

Azure Load Balancer

If we return to the Resource Group created automatically when the AKS cluster was created, we will now see two additional resources. There is now an Azure Load Balancer and Public IP Address.

Similar to the GKE cluster in the last post, when the Istio Ingress Gateway is deployed as part of the platform, it is materialized as an Azure Load Balancer. The front-end of the load balancer is the new public IP address. The back-end of the load-balancer is a pool containing the three AKS worker node VMs. The load balancer is associated with a set of rules and health probes.

DNS

I have associated the new Azure public IP address, connected with the front-end of the load balancer, with the four subdomains I am using to represent the UI and the edge service, Service-A, in both Namespaces. If Azure is your primary Cloud provider, then Azure DNS is a good choice to manage your domain’s DNS records. For this demo, you will require your own domain.

Testing the Platform

With everything deployed, test the platform is responding and generate HTTP traffic for the observability tools to record. Similar to last time, I have chosen hey, a modern load generator and benchmarking tool, and a worthy replacement for Apache Bench (ab). Unlike ab, hey supports HTTP/2. Below, I am running hey directly from Azure Cloud Shell. The tool is simulating 10 concurrent users, generating a total of 500 HTTP GET requests to Service A.

# quick setup from Azure Shell using Bash
go get -u github.com/rakyll/hey
cd go/src/github.com/rakyll/hey/
go build
  
./hey -n 500 -c 10 -h2 http://api.dev.example-api.com/api/ping

We had 100% success with all 500 calls resulting in an HTTP 200 OK success status response code. Based on the results, we can observe the platform was capable of approximately 4 requests/second, with an average response time of 2.48 seconds and a mean time of 2.80 seconds. Almost all of that time was the result of waiting for the response, as the details indicate.

Logging

In this post, we have replaced GCP’s Stackdriver logging with Azure Monitor logs. According to Microsoft, Azure Monitor maximizes the availability and performance of applications by delivering a comprehensive solution for collecting, analyzing, and acting on telemetry from Cloud and on-premises environments. In my opinion, Stackdriver is a superior solution for searching and correlating the logs of distributed applications running on Kubernetes. I find the interface and query language of Stackdriver easier and more intuitive than Azure Monitor, which although powerful, requires substantial query knowledge to obtain meaningful results. For example, here is a query to view the log entries from the services in the dev Namespace, within the last day.

let startTimestamp = ago(1d);
KubePodInventory
| where TimeGenerated > startTimestamp
| where ClusterName =~ "aks-observability-demo"
| where Namespace == "dev"
| where Name contains "service-"
| distinct ContainerID
| join
(
    ContainerLog
    | where TimeGenerated > startTimestamp
)
on ContainerID
| project LogEntrySource, LogEntry, TimeGenerated, Name
| order by TimeGenerated desc
| render table

Below, we see the Logs interface with the search query and log entry results.

Below, we see a detailed view of a single log entry from Service A.

Observability Tools

The previous post goes into greater detail on the features of each of the observability tools provided by Istio, including Prometheus, Grafana, Jaeger, and Kiali.

We can use the exact same kubectl port-forward commands to connect to the tools on AKS as we did on GKE. According to Google, Kubernetes port forwarding allows using a resource name, such as a service name, to select a matching pod to port forward to since Kubernetes v1.10. We forward a local port to a port on the tool’s pod.

# Grafana
kubectl port-forward -n istio-system \
  $(kubectl get pod -n istio-system -l app=grafana \
  -o jsonpath='{.items[0].metadata.name}') 3000:3000 &
  
# Prometheus
kubectl -n istio-system port-forward \
  $(kubectl -n istio-system get pod -l app=prometheus \
  -o jsonpath='{.items[0].metadata.name}') 9090:9090 &
  
# Jaeger
kubectl port-forward -n istio-system \
$(kubectl get pod -n istio-system -l app=jaeger \
-o jsonpath='{.items[0].metadata.name}') 16686:16686 &
  
# Kiali
kubectl -n istio-system port-forward \
  $(kubectl -n istio-system get pod -l app=kiali \
  -o jsonpath='{.items[0].metadata.name}') 20001:20001 &

Prometheus and Grafana

Grafana describes itself as the leading open source software for time series analytics. According to Grafana Labs, Grafana allows you to query, visualize, alert on, and understand your metrics no matter where they are stored. You can easily create, explore, and share visually-rich, data-driven dashboards. Grafana also users to visually define alert rules for your most important metrics. Grafana will continuously evaluate rules and can send notifications.

Jaeger

According to their website, Jaeger, inspired by Dapper and OpenZipkin, is a distributed tracing system released as open source by Uber Technologies. It is used for monitoring and troubleshooting microservices-based distributed systems, including distributed context propagation, distributed transaction monitoring, root cause analysis, service dependency analysis, and performance and latency optimization. The Jaeger website contains a good overview of Jaeger’s architecture and general tracing-related terminology.

Below, we see a typical, distributed trace of the services, starting ingress gateway and passing across the upstream service dependencies.

Kaili

There is a common Kubernetes Secret that controls access to the Kiali API and UI. The default login is admin, the password is 1f2d1e2e67df.

Below, we see a detailed view of our platform, running in the dev namespace, on AKS.

Delete AKS Cluster

Once you are finished with this demo, use the following two commands to tear down the AKS cluster and remove the cluster context from your local configuration.

time az aks delete \
  --name aks-observability-demo \
  --resource-group aks-observability-demo \
  --yes

kubectl config delete-context aks-observability-demo

Conclusion

In this brief, follow-up post, we have explored how the current set of observability tools, part of the latest version of Istio Service Mesh, integrates with Azure Kubernetes Service (AKS).

All opinions expressed in this post are my own and not necessarily the views of my current or past employers or their clients.

AKS, Azure, Azure Kubernetes Service, Cloud, Grafana, Infrastructure, Isio, Jaeger, k8s, Kiali, Logging, Monitoring, Observability, Prometheus, Tracing

1 Comment

Kubernetes-based Microservice Observability with Istio Service Mesh on Google Kubernetes Engine (GKE): Part 2

Posted by Gary A. Stafford in Cloud, DevOps, GCP, Go, JavaScript, Kubernetes, Software Development on March 21, 2019

In this two-part post, we are exploring the set of observability tools that are part of the latest version of Istio Service Mesh. These tools include Prometheus and Grafana for metric collection, monitoring, and alerting, Jaeger for distributed tracing, and Kiali for Istio service-mesh-based microservice visualization. Combined with cloud platform-native monitoring and logging services, such as Stackdriver for Google Kubernetes Engine (GKE) on Google Cloud Platform (GCP), we have a complete observability solution for modern, distributed applications.

Reference Platform

To demonstrate Istio’s observability tools, in part one of the post, we deployed a reference microservices platform, written in Go, to GKE on GCP. The platform is comprised of (14) components, including (8) Go-based microservices, labeled generically as Service A through Service H, (1) Angular 7, TypeScript-based front-end, (4) MongoDB databases, and (1) RabbitMQ queue for event queue-based communications.

The reference platform is designed to generate HTTP-based service-to-service, TCP-based service-to-database (MongoDB), and TCP-based service-to-queue-to-service (RabbitMQ) IPC (inter-process communication). Service A calls Service B and Service C, Service B calls Service D and Service E, Service D produces a message on a RabbitMQ queue that Service F consumes and writes to MongoDB, and so on. The goal is to observe these distributed communications using Istio’s observability tools when the system is deployed to Kubernetes.

Pillar 1: Logging

If you recall, logs, metrics, and traces are often known as the three pillars of observability. Since we are using GKE on GCP, we will look at Google’s Stackdriver Logging. According to Google, Stackdriver Logging allows you to store, search, analyze, monitor, and alert on log data and events from GCP and even AWS. Although Stackdriver logging is not an Istio observability feature, logging is an essential pillar of overall observability strategy.

Go-based Microservice Logging

An effective logging strategy starts with what you log, when you log, and how you log. As part of our logging strategy, the eight Go-based microservices are using Logrus, a popular structured logger for Go. The microservices also implement Banzai Cloud’s logrus-runtime-formatter. There is an excellent article on the formatter, Golang runtime Logrus Formatter. These two logging packages give us greater control over what we log, when we log, and how we log information about our microservices. The recommended configuration of the packages is minimal.

func init() {
   formatter := runtime.Formatter{ChildFormatter: &log.JSONFormatter{}}
   formatter.Line = true
   log.SetFormatter(&formatter)
   log.SetOutput(os.Stdout)
   level, err := log.ParseLevel(getEnv("LOG_LEVEL", "info"))
   if err != nil {
      log.Error(err)
   }
   log.SetLevel(level)
}

Logrus provides several advantages over Go’s simple logging package, log. Log entries are not only for Fatal errors, nor should all verbose log entries be output in a Production environment. The post’s microservices are taking advantage of Logrus’ ability to log at seven levels: Trace, Debug, Info, Warning, Error, Fatal, and Panic. We have also variabilized the log level, allowing it to be easily changed in the Kubernetes Deployment resource at deploy-time.

The microservices also take advantage of Banzai Cloud’s logrus-runtime-formatter. The Banzai formatter automatically tags log messages with runtime/stack information, including function name and line number; extremely helpful when troubleshooting. We are also using Logrus’ JSON formatter. Note how each log entry below has the JSON payload contained within the message.

Client-side Angular UI Logging

Likewise, we have enhanced the logging of the Angular UI using NGX Logger. NGX Logger is a popular, simple logging module, currently for Angular 6 and 7. It allows “pretty print” to the console, as well as allowing log messages to be POSTed to a URL for server-side logging. For this demo, we will only print to the console. Similar to Logrus, NGX Logger supports multiple log levels: Trace, Debug, Info, Warning, Error, Fatal, and Off. Instead of just outputting messages, NGX Logger allows us to output properly formatted log entries to the web browser’s console.

The level of logs output is dependent on the environment, Production or not Production. Below we see a combination of log entries in the local development environment, including Debug, Info, and Error.

Again below, we see the same page in the GKE-based Production environment. Note the absence of Debug-level log entries output to the console, without changing the configuration. We would not want to expose potentially sensitive information in verbose log output to our end-users in Production.

Controlling logging levels is accomplished by adding the following ternary operator to the app.module.ts file.

    LoggerModule.forRoot({
      level: !environment.production ? 
        NgxLoggerLevel.DEBUG : NgxLoggerLevel.INFO,
        serverLogLevel: NgxLoggerLevel.INFO
    })

Pillar 2: Metrics

For metrics, we will examine at Prometheus and Grafana. Both these leading tools were installed as part of the Istio deployment.

Prometheus

According to Istio, Istio’s Mixer comes with a built-in Prometheus adapter that exposes an endpoint serving generated metric values. The Prometheus add-on is a Prometheus server that comes pre-configured to scrape Mixer endpoints to collect the exposed metrics. It provides a mechanism for persistent storage and querying of Istio metrics.

With the GKE cluster running, Istio installed, and the platform deployed, the easiest way to access Grafana, is using kubectl port-forward to connect to the Prometheus server. According to Google, Kubernetes port forwarding allows using a resource name, such as a service name, to select a matching pod to port forward to since Kubernetes v1.10. We forward a local port to a port on the Prometheus pod.

You may connect using Google Cloud Shell or copy and paste the command to your local shell to connect from a local port. Below are the port forwarding commands used in this post.

# Grafana
kubectl port-forward -n istio-system \
  $(kubectl get pod -n istio-system -l app=grafana \
  -o jsonpath='{.items[0].metadata.name}') 3000:3000 &
  
# Prometheus
kubectl -n istio-system port-forward \
  $(kubectl -n istio-system get pod -l app=prometheus \
  -o jsonpath='{.items[0].metadata.name}') 9090:9090 &
  
# Jaeger
kubectl port-forward -n istio-system \
$(kubectl get pod -n istio-system -l app=jaeger \
-o jsonpath='{.items[0].metadata.name}') 16686:16686 &
  
# Kiali
kubectl -n istio-system port-forward \
  $(kubectl -n istio-system get pod -l app=kiali \
  -o jsonpath='{.items[0].metadata.name}') 20001:20001 &

According to Prometheus, user select and aggregate time series data in real time using a functional query language called PromQL (Prometheus Query Language). The result of an expression can either be shown as a graph, viewed as tabular data in Prometheus’s expression browser, or consumed by external systems through Prometheus’ HTTP API. The expression browser includes a drop-down menu with all available metrics as a starting point for building queries. Shown below are a few PromQL examples used in this post.

up{namespace="dev",pod_name=~"service-.*"}

container_memory_max_usage_bytes{namespace="dev",container_name=~"service-.*"}
container_memory_max_usage_bytes{namespace="dev",container_name="service-f"}
container_network_transmit_packets_total{namespace="dev",pod_name=~"service-e-.*"}

istio_requests_total{destination_service_namespace="dev",connection_security_policy="mutual_tls",destination_app="service-a"}
istio_response_bytes_count{destination_service_namespace="dev",connection_security_policy="mutual_tls",source_app="service-a"}

Below, in the Prometheus console, we see an example graph of the eight Go-based microservices, deployed to GKE. The graph displays the container memory usage over a five minute period. For half the time period, the services were at rest. For the second half of the period, the services were under a simulated load, using hey. Viewing the memory profile of the services under load can help us determine the container memory minimums and limits, which impact Kubernetes’ scheduling of workloads on the GKE cluster. Metrics such as this might also uncover memory leaks or routing issues, such as the service below, which appears to be consuming 25-50% more memory than its peers.

Another example, below, we see a graph representing the total Istio requests to Service A in the dev Namespace, while the system was under load.

Compare the graph view above with the same metrics displayed the console view. The multiple entries reflect the multiple instances of Service A in the dev Namespace, over the five-minute period being examined. The values in the individual metric elements indicate the latest metric that was collected.

Prometheus also collects basic metrics about Istio components, Kubernetes components, and GKE cluster. Below we can view the total memory of each n1-standard-2 VM nodes in the GKE cluster.

Grafana

Grafana describes itself as the leading open source software for time series analytics. According to Grafana Labs, Grafana allows you to query, visualize, alert on, and understand your metrics no matter where they are stored. You can easily create, explore, and share visually-rich, data-driven dashboards. Grafana also users to visually define alert rules for your most important metrics. Grafana will continuously evaluate rules and can send notifications.

According to Istio, the Grafana add-on is a pre-configured instance of Grafana. The Grafana Docker base image has been modified to start with both a Prometheus data source and the Istio Dashboard installed. The base install files for Istio, and Mixer in particular, ship with a default configuration of global (used for every service) metrics. The pre-configured Istio Dashboards are built to be used in conjunction with the default Istio metrics configuration and a Prometheus back-end.

Below, we see the pre-configured Istio Workload Dashboard. This particular section of the larger dashboard has been filtered to show outbound service metrics in the dev Namespace of our GKE cluster.

Similarly, below, we see the pre-configured Istio Service Dashboard. This particular section of the larger dashboard is filtered to show client workloads metrics for the Istio Ingress Gateway in our GKE cluster.

Lastly, we see the pre-configured Istio Mesh Dashboard. This dashboard is filtered to show a table view of metrics for components deployed to our GKE cluster.

An effective observability strategy must include more than just the ability to visualize results. An effective strategy must also include the ability to detect anomalies and notify (alert) the appropriate resources or take action directly to resolve incidents. Grafana, like Prometheus, is capable of alerting and notification. You visually define alert rules for your critical metrics. Grafana will continuously evaluate metrics against the rules and send notifications when pre-defined thresholds are breached.

Prometheus supports multiple, popular notification channels, including PagerDuty, HipChat, Email, Kafka, and Slack. Below, we see a new Prometheus notification channel, which sends alert notifications to a Slack support channel.

Prometheus is able to send detailed text-based and visual notifications.

Pillar 3: Traces

According to the Open Tracing website, distributed tracing, also called distributed request tracing, is a method used to profile and monitor applications, especially those built using a microservices architecture. Distributed tracing helps pinpoint where failures occur and what causes poor performance.

According to Istio, although Istio proxies are able to automatically send spans, applications need to propagate the appropriate HTTP headers, so that when the proxies send span information, the spans can be correlated correctly into a single trace. To accomplish this, an application needs to collect and propagate the following headers from the incoming request to any outgoing requests.

x-request-id
x-b3-traceid
x-b3-spanid
x-b3-parentspanid
x-b3-sampled
x-b3-flags
x-ot-span-context

The x-b3 headers originated as part of the Zipkin project. The B3 portion of the header is named for the original name of Zipkin, BigBrotherBird. Passing these headers across service calls is known as B3 propagation. According to Zipkin, these attributes are propagated in-process, and eventually downstream (often via HTTP headers), to ensure all activity originating from the same root are collected together.

In order to demonstrate distributed tracing with Jaeger, I have modified Service A, Service B, and Service E. These are the three services that make HTTP requests to other upstream services. I have added the following code in order to propagate the headers from one service to the next. The Istio sidecar proxy (Envoy) generates the first headers. It is critical that you only propagate the headers that are present in the downstream request and have a value, as the code below does. Propagating an empty header will break the distributed tracing.

headers := []string{
  "x-request-id",
  "x-b3-traceid",
  "x-b3-spanid",
  "x-b3-parentspanid",
  "x-b3-sampled",
  "x-b3-flags",
  "x-ot-span-context",
}

for _, header := range headers {
  if r.Header.Get(header) != "" {
    req.Header.Add(header, r.Header.Get(header))
  }
}

Below, in the highlighted Stackdriver log entry’s JSON payload, we see the required headers, propagated from the root span, which contained a value, being passed from Service A to Service C in the upstream request.

Jaeger

According to their website, Jaeger, inspired by Dapper and OpenZipkin, is a distributed tracing system released as open source by Uber Technologies. It is used for monitoring and troubleshooting microservices-based distributed systems, including distributed context propagation, distributed transaction monitoring, root cause analysis, service dependency analysis, and performance and latency optimization. The Jaeger website contains a good overview of Jaeger’s architecture and general tracing-related terminology.

Below we see the Jaeger UI Traces View. The UI shows the results of a search for the Istio Ingress Gateway service over a period of about forty minutes. We see a timeline of traces across the top with a list of trace results below. As discussed on the Jaeger website, a trace is composed of spans. A span represents a logical unit of work in Jaeger that has an operation name. A trace is an execution path through the system and can be thought of as a directed acyclic graph (DAG) of spans. If you have worked with systems like Apache Spark, you are probably already familiar with DAGs.

Below we see the Jaeger UI Trace Detail View. The example trace contains 16 spans, which encompasses eight services – seven of the eight Go-based services and the Istio Ingress Gateway. The trace and the spans each have timings. The root span in the trace is the Istio Ingress Gateway. The Angular UI, loaded in the end user’s web browser, calls the mesh’s edge service, Service A, through the Istio Ingress Gateway. From there, we see the expected flow of our service-to-service IPC. Service A calls Services B and C. Service B calls Service E, which calls Service G and Service H. In this demo, traces do not span the RabbitMQ message queues. This means you would not see a trace which includes a call from Service D to Service F, via the RabbitMQ.

The latest version of Jaeger also includes a Compare feature and two Dependencies views, Force-Directed Graph, and DAG. I find both views rather primitive compared to Kiali, and more similar to Service Graph. Lacking access to Kiali, the views are marginally useful as a dependency graph.

Kiali: Microservice Observability

According to their website, Kiali provides answers to the questions: What are the microservices in my Istio service mesh, and how are they connected? There is a common Kubernetes Secret that controls access to the Kiali API and UI. The default login is admin, the password is 1f2d1e2e67df.

Logging into Kiali, we see the Overview menu entry, which provides a global view of all namespaces within the Istio service mesh and the number of applications within each namespace.

The Graph View in the Kiali UI is a visual representation of the components running in the Istio service mesh. Below, filtering on the cluster’s dev Namespace, we can observe that Kiali has mapped 8 applications (workloads), 10 services, and 24 edges (a graph term). Specifically, we see the Istio Ingres Proxy at the edge of the service mesh, the Angular UI, the eight Go-based microservices and their Envoy proxy sidecars that are taking traffic (Service F did not take any direct traffic from another service in this example), the external MongoDB Atlas cluster, and the external CloudAMQP cluster. Note how service-to-service traffic flows, with Istio, from the service to its sidecar proxy, to the other service’s sidecar proxy, and finally to the service.

Below, we see a similar view of the service mesh, but this time, there are failures between the Istio Ingress Gateway and the Service A, shown in red. We can also observe overall metrics for the HTTP traffic, such as total requests/minute, errors, and status codes.

Kiali can also display average requests times and other metrics for each edge in the graph (the communication between two components).

Kiali can also show application versions deployed, as shown below, the microservices are a combination of versions 1.3 and 1.4.

Focusing on the external MongoDB Atlas cluster, Kiali also allows us to view TCP traffic between the four services within the service mesh and the external cluster.

The Applications menu entry lists all the applications and their error rates, which can be filtered by Namespace and time interval. Here we see that the Angular UI was producing errors at the rate of 16.67%.

On both the Applications and Workloads menu entry, we can drill into a component to view additional details, including the overall health, number of Pods, Services, and Destination Services. Below, we see details for Service B in the dev Namespace.

The Workloads detailed view also includes inbound and outbound metrics. Below, the outbound volume, duration, and size metrics, for Service A in the dev Namespace.

Finally, Kiali presents an Istio Config menu entry. The Istio Config menu entry displays a list of all of the available Istio configuration objects that exist in the user’s environment.

Oftentimes, I find Kiali to be my first stop when troubleshooting platform issues. Once I identify the specific components or communication paths having issues, I can search the Stackdriver logs and the Prometheus metrics, through the Grafana dashboard.

Conclusion

In this two-part post, we have explored the current set of observability tools, which are part of the latest version of Istio Service Mesh. These tools included Prometheus and Grafana for metric collection, monitoring, and alerting, Jaeger for distributed tracing, and Kiali for Istio service-mesh-based microservice visualization. Combined with cloud platform-native monitoring and logging services, such as Stackdriver for Google Kubernetes Engine (GKE) on Google Cloud Platform (GCP), we have a complete observability solution for modern, distributed applications.

All opinions expressed in this post are my own and not necessarily the views of my current or past employers or their clients.

GCP, GKE, Google Cloud Platform, Grafana, Istio, Jaeger, Kiali, Logging, Metrics, Monitoring, Observability, Prometheus, Service Mesh, Stackdriver, Tracing

4 Comments

Kubernetes-based Microservice Observability with Istio Service Mesh on Google Kubernetes Engine (GKE): Part 1

Posted by Gary A. Stafford in Build Automation, Client-Side Development, Cloud, DevOps, GCP, Go, JavaScript, Kubernetes, Software Development on March 10, 2019

In this two-part post, we will explore the set of observability tools which are part of the Istio Service Mesh. These tools include Jaeger, Kiali, Prometheus, and Grafana. To assist in our exploration, we will deploy a Go-based, microservices reference platform to Google Kubernetes Engine, on the Google Cloud Platform.

What is Observability?

Similar to blockchain, serverless, AI and ML, chatbots, cybersecurity, and service meshes, Observability is a hot buzz word in the IT industry right now. According to Wikipedia, observability is a measure of how well internal states of a system can be inferred from knowledge of its external outputs. Logs, metrics, and traces are often known as the three pillars of observability. These are the external outputs of the system, which we may observe.

The O’Reilly book, Distributed Systems Observability, by Cindy Sridharan, does an excellent job of detailing ‘The Three Pillars of Observability’, in Chapter 4. I recommend reading this free online excerpt, before continuing. A second great resource for information on observability is honeycomb.io, a developer of observability tools for production systems, led by well-known industry thought-leader, Charity Majors. The honeycomb.io site includes articles, blog posts, whitepapers, and podcasts on observability.

As modern distributed systems grow ever more complex, the ability to observe those systems demands equally modern tooling that was designed with this level of complexity in mind. Traditional logging and monitoring systems often struggle with today’s hybrid and multi-cloud, polyglot language-based, event-driven, container-based and serverless, infinitely-scalable, ephemeral-compute platforms.

Tools like Istio Service Mesh attempt to solve the observability challenge by offering native integrations with several best-of-breed, open-source telemetry tools. Istio’s integrations include Jaeger for distributed tracing, Kiali for Istio service mesh-based microservice visualization, and Prometheus and Grafana for metric collection, monitoring, and alerting. Combined with cloud platform-native monitoring and logging services, such as Stackdriver for Google Kubernetes Engine (GKE) on Google Cloud Platform (GCP), we have a complete observability platform for modern, distributed applications.

A Reference Microservices Platform

To demonstrate the observability tools integrated with the latest version of Istio Service Mesh, we will deploy a reference microservices platform, written in Go, to GKE on GCP. I developed the reference platform to demonstrate concepts such as API management, Service Meshes, Observability, DevOps, and Chaos Engineering. The platform is comprised of (14) components, including (8) Go-based microservices, labeled generically as Service A – Service H, (1) Angular 7, TypeScript-based front-end, (4) MongoDB databases, and (1) RabbitMQ queue for event queue-based communications. The platform and all its source code is free and open source.

The reference platform is designed to generate HTTP-based service-to-service, TCP-based service-to-database (MongoDB), and TCP-based service-to-queue-to-service (RabbitMQ) IPC (inter-process communication). Service A calls Service B and Service C, Service B calls Service D and Service E, Service D produces a message on a RabbitMQ queue that Service F consumes and writes to MongoDB, and so on. These distributed communications can be observed using Istio’s observability tools when the system is deployed to a Kubernetes cluster running the Istio service mesh.

Service Responses

On the reference platform, each upstream service responds to requests from downstream services by returning a small informational JSON payload (termed a greeting in the source code).

The responses are aggregated across the service call chain, resulting in an array of service responses being returned to the edge service and on to the Angular-based UI, running in the end user’s web browser. The response aggregation feature is simply used to confirm that the service-to-service communications, Istio components, and the telemetry tools are working properly.

Each Go microservice contains a /ping and /health endpoint. The /health endpoint can be used to configure Kubernetes Liveness and Readiness Probes. Additionally, the edge service, Service A, is configured for Cross-Origin Resource Sharing (CORS) using the access-control-allow-origin: * response header. CORS allows the Angular UI, running in end user’s web browser, to call the Service A /ping endpoint, which resides in a different subdomain from UI. Shown below is the Go source code for Service A.

	// author: Gary A. Stafford
	// site: https://programmaticponderings.com
	// license: MIT License
	// purpose: Service A

	package main

	import (
	"encoding/json"
	"github.com/banzaicloud/logrus-runtime-formatter"
	"github.com/google/uuid"
	"github.com/gorilla/mux"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/rs/cors"
	log "github.com/sirupsen/logrus"
	"io/ioutil"
	"net/http"
	"os"
	"strconv"
	"time"
	)

	type Greeting struct {
	ID string `json:"id,omitempty"`
	ServiceName string `json:"service,omitempty"`
	Message string `json:"message,omitempty"`
	CreatedAt time.Time `json:"created,omitempty"`
	}

	var greetings []Greeting

	func PingHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")

	log.Debug(r)

	greetings = nil

	CallNextServiceWithTrace("http://service-b/api/ping", w, r)
	CallNextServiceWithTrace("http://service-c/api/ping", w, r)

	tmpGreeting := Greeting{
	ID: uuid.New().String(),
	ServiceName: "Service-A",
	Message: "Hello, from Service-A!",
	CreatedAt: time.Now().Local(),
	}

	greetings = append(greetings, tmpGreeting)

	err := json.NewEncoder(w).Encode(greetings)
	if err != nil {
	log.Error(err)
	}
	}

	func HealthCheckHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	_, err := w.Write([]byte("{\"alive\": true}"))
	if err != nil {
	log.Error(err)
	}
	}

	func ResponseStatusHandler(w http.ResponseWriter, r *http.Request) {
	params := mux.Vars(r)
	statusCode, err := strconv.Atoi(params["code"])
	if err != nil {
	log.Error(err)
	}
	w.WriteHeader(statusCode)

	}

	func CallNextServiceWithTrace(url string, w http.ResponseWriter, r *http.Request) {
	var tmpGreetings []Greeting

	w.Header().Set("Content-Type", "application/json; charset=utf-8")

	req, err := http.NewRequest("GET", url, nil)
	if err != nil {
	log.Error(err)
	}

	// Headers must be passed for Jaeger Distributed Tracing
	headers := []string{
	"x-request-id",
	"x-b3-traceid",
	"x-b3-spanid",
	"x-b3-parentspanid",
	"x-b3-sampled",
	"x-b3-flags",
	"x-ot-span-context",
	}

	for _, header := range headers {
	if r.Header.Get(header) != "" {
	req.Header.Add(header, r.Header.Get(header))
	}
	}

	log.Info(req)

	client := &http.Client{}
	response, err := client.Do(req)

	if err != nil {
	log.Error(err)
	}

	defer response.Body.Close()

	body, err := ioutil.ReadAll(response.Body)
	if err != nil {
	log.Error(err)
	}

	err = json.Unmarshal(body, &tmpGreetings)
	if err != nil {
	log.Error(err)
	}

	for _, r := range tmpGreetings {
	greetings = append(greetings, r)
	}
	}

	func getEnv(key, fallback string) string {
	if value, ok := os.LookupEnv(key); ok {
	return value
	}
	return fallback
	}

	func init() {
	formatter := runtime.Formatter{ChildFormatter: &log.JSONFormatter{}}
	formatter.Line = true
	log.SetFormatter(&formatter)
	log.SetOutput(os.Stdout)
	level, err := log.ParseLevel(getEnv("LOG_LEVEL", "info"))
	if err != nil {
	log.Error(err)
	}
	log.SetLevel(level)
	}

	func main() {
	c := cors.New(cors.Options{
	AllowedOrigins: []string{"*"},
	AllowCredentials: true,
	AllowedMethods: []string{"GET", "POST", "PATCH", "PUT", "DELETE", "OPTIONS"},
	})
	router := mux.NewRouter()
	api := router.PathPrefix("/api").Subrouter()
	api.HandleFunc("/ping", PingHandler).Methods("GET", "OPTIONS")
	api.HandleFunc("/health", HealthCheckHandler).Methods("GET", "OPTIONS")
	api.HandleFunc("/status/{code}", ResponseStatusHandler).Methods("GET", "OPTIONS")
	api.Handle("/metrics", promhttp.Handler())
	handler := c.Handler(router)
	log.Fatal(http.ListenAndServe(":80", handler))
	}

view raw

main.go

hosted with ❤ by GitHub

For this demonstration, the MongoDB databases will be hosted, external to the services on GCP, on MongoDB Atlas, a MongoDB-as-a-Service, cloud-based platform. Similarly, the RabbitMQ queues will be hosted on CloudAMQP, a RabbitMQ-as-a-Service, cloud-based platform. I have used both of these SaaS providers in several previous posts. Using external services will help us understand how Istio and its observability tools collect telemetry for communications between the Kubernetes cluster and external systems.

Shown below is the Go source code for Service F, This service consumers messages from the RabbitMQ queue, placed there by Service D, and writes the messages to MongoDB.

	// author: Gary A. Stafford
	// site: https://programmaticponderings.com
	// license: MIT License
	// purpose: Service F

	package main

	import (
	"bytes"
	"context"
	"encoding/json"
	"github.com/banzaicloud/logrus-runtime-formatter"
	"github.com/google/uuid"
	"github.com/gorilla/mux"
	log "github.com/sirupsen/logrus"
	"github.com/streadway/amqp"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"net/http"
	"os"
	"time"
	)

	type Greeting struct {
	ID string `json:"id,omitempty"`
	ServiceName string `json:"service,omitempty"`
	Message string `json:"message,omitempty"`
	CreatedAt time.Time `json:"created,omitempty"`
	}

	var greetings []Greeting

	func PingHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")

	greetings = nil

	tmpGreeting := Greeting{
	ID: uuid.New().String(),
	ServiceName: "Service-F",
	Message: "Hola, from Service-F!",
	CreatedAt: time.Now().Local(),
	}

	greetings = append(greetings, tmpGreeting)

	CallMongoDB(tmpGreeting)

	err := json.NewEncoder(w).Encode(greetings)
	if err != nil {
	log.Error(err)
	}
	}

	func HealthCheckHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	_, err := w.Write([]byte("{\"alive\": true}"))
	if err != nil {
	log.Error(err)
	}
	}

	func CallMongoDB(greeting Greeting) {
	log.Info(greeting)
	ctx, _ := context.WithTimeout(context.Background(), 10*time.Second)
	client, err := mongo.Connect(ctx, options.Client().ApplyURI(os.Getenv("MONGO_CONN")))
	if err != nil {
	log.Error(err)
	}

	defer client.Disconnect(nil)

	collection := client.Database("service-f").Collection("messages")
	ctx, _ = context.WithTimeout(context.Background(), 5*time.Second)

	_, err = collection.InsertOne(ctx, greeting)
	if err != nil {
	log.Error(err)
	}
	}

	func GetMessages() {
	conn, err := amqp.Dial(os.Getenv("RABBITMQ_CONN"))
	if err != nil {
	log.Error(err)
	}
	defer conn.Close()

	ch, err := conn.Channel()
	if err != nil {
	log.Error(err)
	}
	defer ch.Close()

	q, err := ch.QueueDeclare(
	"service-d",
	false,
	false,
	false,
	false,
	nil,
	)
	if err != nil {
	log.Error(err)
	}

	msgs, err := ch.Consume(
	q.Name,
	"service-f",
	true,
	false,
	false,
	false,
	nil,
	)
	if err != nil {
	log.Error(err)
	}

	forever := make(chan bool)

	go func() {
	for delivery := range msgs {
	log.Debug(delivery)
	CallMongoDB(deserialize(delivery.Body))
	}
	}()

	<-forever
	}

	func deserialize(b []byte) (t Greeting) {
	log.Debug(b)
	var tmpGreeting Greeting
	buf := bytes.NewBuffer(b)
	decoder := json.NewDecoder(buf)
	err := decoder.Decode(&tmpGreeting)
	if err != nil {
	log.Error(err)
	}
	return tmpGreeting
	}

	func getEnv(key, fallback string) string {
	if value, ok := os.LookupEnv(key); ok {
	return value
	}
	return fallback
	}

	func init() {
	formatter := runtime.Formatter{ChildFormatter: &log.JSONFormatter{}}
	formatter.Line = true
	log.SetFormatter(&formatter)
	log.SetOutput(os.Stdout)
	level, err := log.ParseLevel(getEnv("LOG_LEVEL", "info"))
	if err != nil {
	log.Error(err)
	}
	log.SetLevel(level)
	}

	func main() {
	go GetMessages()

	router := mux.NewRouter()
	api := router.PathPrefix("/api").Subrouter()
	api.HandleFunc("/ping", PingHandler).Methods("GET")
	api.HandleFunc("/health", HealthCheckHandler).Methods("GET")
	log.Fatal(http.ListenAndServe(":80", router))
	}

view raw

main.go

hosted with ❤ by GitHub

Source Code

All source code for this post is available on GitHub in two projects. The Go-based microservices source code, all Kubernetes resources, and all deployment scripts are located in the k8s-istio-observe-backend project repository. The Angular UI TypeScript-based source code is located in the k8s-istio-observe-frontend project repository. You should not need to clone the Angular UI project for this demonstration.

git clone --branch master --single-branch --depth 1 --no-tags \
  https://github.com/garystafford/k8s-istio-observe-backend.git

Docker images referenced in the Kubernetes Deployment resource files, for the Go services and UI, are all available on Docker Hub. The Go microservice Docker images were built using the official Golang Alpine base image on DockerHub, containing Go version 1.12.0. Using the Alpine image to compile the Go source code ensures the containers will be as small as possible and contain a minimal attack surface.

System Requirements

To follow along with the post, you will need the latest version of gcloud CLI (min. ver. 239.0.0), part of the Google Cloud SDK, Helm, and the just releases Istio 1.1.0, installed and configured locally or on your build machine.

Set-up and Installation

To deploy the microservices platform to GKE, we will proceed in the following order.

Create the MongoDB Atlas database cluster;
Create the CloudAMQP RabbitMQ cluster;
Modify the Kubernetes resources and scripts for your own environments;
Create the GKE cluster on GCP;
Deploy Istio 1.1.0 to the GKE cluster, using Helm;
Create DNS records for the platform’s exposed resources;
Deploy the Go-based microservices, Angular UI, and associated resources to GKE;
Test and troubleshoot the platform;
Observe the results in part two!

MongoDB Atlas Cluster

MongoDB Atlas is a fully-managed MongoDB-as-a-Service, available on AWS, Azure, and GCP. Atlas, a mature SaaS product, offers high-availability, guaranteed uptime SLAs, elastic scalability, cross-region replication, enterprise-grade security, LDAP integration, a BI Connector, and much more.

MongoDB Atlas currently offers four pricing plans, Free, Basic, Pro, and Enterprise. Plans range from the smallest, M0-sized MongoDB cluster, with shared RAM and 512 MB storage, up to the massive M400 MongoDB cluster, with 488 GB of RAM and 3 TB of storage.

For this post, I have created an M2-sized MongoDB cluster in GCP’s us-central1 (Iowa) region, with a single user database account for this demo. The account will be used to connect from four of the eight microservices, running on GKE.

Originally, I started with an M0-sized cluster, but the compute resources were insufficient to support the volume of calls from the Go-based microservices. I suggest at least an M2-sized cluster or larger.

CloudAMQP RabbitMQ Cluster

CloudAMQP provides full-managed RabbitMQ clusters on all major cloud and application platforms. RabbitMQ will support a decoupled, eventually consistent, message-based architecture for a portion of our Go-based microservices. For this post, I have created a RabbitMQ cluster in GCP’s us-central1 (Iowa) region, the same as our GKE cluster and MongoDB Atlas cluster. I chose a minimally-configured free version of RabbitMQ. CloudAMQP also offers robust, multi-node RabbitMQ clusters for Production use.

Modify Configurations

There are a few configuration settings you will need to change in the GitHub project’s Kubernetes resource files and Bash deployment scripts.

Istio ServiceEntry for MongoDB Atlas

Modify the Istio ServiceEntry, external-mesh-mongodb-atlas.yaml file, adding you MongoDB Atlas host address. This file allows egress traffic from four of the microservices on GKE to the external MongoDB Atlas cluster.

apiVersion: networking.istio.io/v1alpha3
kind: ServiceEntry
metadata:
  name: mongodb-atlas-external-mesh
spec:
  hosts:
  - {{ your_host_goes_here }}
  ports:
  - name: mongo
    number: 27017
    protocol: MONGO
  location: MESH_EXTERNAL
  resolution: NONE

Istio ServiceEntry for CloudAMQP RabbitMQ

Modify the Istio ServiceEntry, external-mesh-cloudamqp.yaml file, adding you CloudAMQP host address. This file allows egress traffic from two of the microservices to the CloudAMQP cluster.

apiVersion: networking.istio.io/v1alpha3
kind: ServiceEntry
metadata:
  name: cloudamqp-external-mesh
spec:
  hosts:
  - {{ your_host_goes_here }}
  ports:
  - name: rabbitmq
    number: 5672
    protocol: TCP
  location: MESH_EXTERNAL
  resolution: NONE

Istio Gateway and VirtualService Resources

There are numerous strategies you may use to route traffic into the GKE cluster, via Istio. I am using a single domain for the post, example-api.com, and four subdomains. One set of subdomains is for the Angular UI, in the dev Namespace (ui.dev.example-api.com) and the test Namespace (ui.test.example-api.com). The other set of subdomains is for the edge API microservice, Service A, which the UI calls (api.dev.example-api.com and api.test.example-api.com). Traffic is routed to specific Kubernetes Service resources, based on the URL.

According to Istio, the Gateway describes a load balancer operating at the edge of the mesh, receiving incoming or outgoing HTTP/TCP connections. Modify the Istio ingress Gateway, inserting your own domains or subdomains in the hosts section. These are the hosts on port 80 that will be allowed into the mesh.

apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: demo-gateway
spec:
  selector:
    istio: ingressgateway
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - ui.dev.example-api.com
    - ui.test.example-api.com
    - api.dev.example-api.com
    - api.test.example-api.com

According to Istio, a VirtualService defines a set of traffic routing rules to apply when a host is addressed. A VirtualService is bound to a Gateway to control the forwarding of traffic arriving at a particular host and port. Modify the project’s four Istio VirtualServices, inserting your own domains or subdomains. Here is an example of one of the four VirtualServices, in the istio-gateway.yaml file.

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: angular-ui-dev
spec:
  hosts:
  - ui.dev.example-api.com
  gateways:
  - demo-gateway
  http:
  - match:
    - uri:
        prefix: /
    route:
    - destination:
        port:
          number: 80
        host: angular-ui.dev.svc.cluster.local

Kubernetes Secret

The project contains a Kubernetes Secret, go-srv-demo.yaml, with two values. One is for the MongoDB Atlas connection string and one is for the CloudAMQP connections string. Remember Kubernetes Secret values need to be base64 encoded.

apiVersion: v1
kind: Secret
metadata:
  name: go-srv-config
type: Opaque
data:
  mongodb.conn: {{ your_base64_encoded_secret }}
  rabbitmq.conn: {{ your_base64_encoded_secret }}

On Linux and Mac, you can use the base64 program to encode the connection strings.

> echo -n "mongodb+srv://username:password@atlas-cluster.gcp.mongodb.net/test?retryWrites=true" | base64
bW9uZ29kYitzcnY6Ly91c2VybmFtZTpwYXNzd29yZEBhdGxhcy1jbHVzdGVyLmdjcC5tb25nb2RiLm5ldC90ZXN0P3JldHJ5V3JpdGVzPXRydWU=

> echo -n "amqp://username:password@rmq.cloudamqp.com/cluster" | base64
YW1xcDovL3VzZXJuYW1lOnBhc3N3b3JkQHJtcS5jbG91ZGFtcXAuY29tL2NsdXN0ZXI=

Bash Scripts Variables

The bash script, part3_create_gke_cluster.sh, contains a series of environment variables. At a minimum, you will need to change the PROJECT variable in all scripts to match your GCP project name.

# Constants - CHANGE ME!
readonly PROJECT='{{ your_gcp_project_goes_here }}'
readonly CLUSTER='go-srv-demo-cluster'
readonly REGION='us-central1'
readonly MASTER_AUTH_NETS='72.231.208.0/24'
readonly GKE_VERSION='1.12.5-gke.5'
readonly MACHINE_TYPE='n1-standard-2'

The bash script, part4_install_istio.sh, includes the ISTIO_HOME variable. The value should correspond to your local path to Istio 1.1.0. On my local Mac, this value is shown below.

readonly ISTIO_HOME='/Applications/istio-1.1.0'

Deploy GKE Cluster

Next, deploy the GKE cluster using the included bash script, part3_create_gke_cluster.sh. This will create a Regional, multi-zone, 3-node GKE cluster, using the latest version of GKE at the time of this post, 1.12.5-gke.5. The cluster will be deployed to the same region as the MongoDB Atlas and CloudAMQP clusters, GCP’s us-central1 (Iowa) region. Planning where your Cloud resources will reside, for both SaaS providers and primary Cloud providers can be critical to minimizing latency for network I/O intensive applications.

Deploy Istio using Helm

With the GKE cluster and associated infrastructure in place, deploy Istio. For this post, I have chosen to install Istio using Helm, as recommended my Istio. To deploy Istio using Helm, use the included bash script, part4_install_istio.sh.

The script installs Istio, using the Helm Chart in the local Istio 1.1.0 install/kubernetes/helm/istio directory, which you installed as a requirement for this demonstration. The Istio install script overrides several default values in the Istio Helm Chart using the --set, flag. The list of available configuration values is detailed in the Istio Chart’s GitHub project. The options enable Istio’s observability features, which we will explore in part two. Features include Kiali, Grafana, Prometheus, and Jaeger.

helm install ${ISTIO_HOME}/install/kubernetes/helm/istio-init \
  --name istio-init \
  --namespace istio-system

helm install ${ISTIO_HOME}/install/kubernetes/helm/istio \
  --name istio \
  --namespace istio-system \
  --set prometheus.enabled=true \
  --set grafana.enabled=true \
  --set kiali.enabled=true \
  --set tracing.enabled=true

kubectl apply --namespace istio-system \
  -f ./resources/secrets/kiali.yaml

Below, we see the Istio-related Workloads running on the cluster, including the observability tools.

Below, we see the corresponding Istio-related Service resources running on the cluster.

Modify DNS Records

Instead of using IP addresses to route traffic the GKE cluster and its applications, we will use DNS. As explained earlier, I have chosen a single domain for the post, example-api.com, and four subdomains. One set of subdomains is for the Angular UI, in the dev Namespace and the test Namespace. The other set of subdomains is for the edge microservice, Service A, which the API calls. Traffic is routed to specific Kubernetes Service resources, based on the URL.

Deploying the GKE cluster and Istio triggers the creation of a Google Load Balancer, four IP addresses, and all required firewall rules. One of the four IP addresses, the one shown below, associated with the Forwarding rule, will be associated with the front-end of the load balancer.

Below, we see the new load balancer, with the front-end IP address and the backend VM pool of three GKE cluster’s worker nodes. Each node is assigned one of the IP addresses, as shown above.

As shown below, using Google Cloud DNS, I have created the four subdomains and assigned the IP address of the load balancer’s front-end to all four subdomains. Ingress traffic to these addresses will be routed through the Istio ingress Gateway and the four Istio VirtualServices, to the appropriate Kubernetes Service resources. Use your choice of DNS management tools to create the four A Type DNS records.

Deploy the Reference Platform

Next, deploy the eight Go-based microservices, the Angular UI, and the associated Kubernetes and Istio resources to the GKE cluster. To deploy the platform, use the included bash deploy script, part5a_deploy_resources.sh. If anything fails and you want to remove the existing resources and re-deploy, without destroying the GKE cluster or Istio, you can use the part5b_delete_resources.sh delete script.

The deploy script deploys all the resources two Kubernetes Namespaces, dev and test. This will allow us to see how we can differentiate between Namespaces when using the observability tools.

Below, we see the Istio-related resources, which we just deployed. They include the Istio Gateway, four Istio VirtualService, and two Istio ServiceEntry resources.

Below, we see the platform’s Workloads (Kubernetes Deployment resources), running on the cluster. Here we see two Pods for each Workload, a total of 18 Pods, running in the dev Namespace. Each Pod contains both the deployed microservice or UI component, as well as a copy of Istio’s Envoy Proxy.

Below, we see the corresponding Kubernetes Service resources running in the dev Namespace.

Below, a similar view of the Deployment resources running in the test Namespace. Again, we have two Pods for each deployment with each Pod contains both the deployed microservice or UI component, as well as a copy of Istio’s Envoy Proxy.

Test the Platform

We do want to ensure the platform’s eight Go-based microservices and Angular UI are working properly, communicating with each other, and communicating with the external MongoDB Atlas and CloudAMQP RabbitMQ clusters. The easiest way to test the cluster is by viewing the Angular UI in a web browser.

The UI requires you to input the host domain of the Service A, the API’s edge service. Since you cannot use my subdomain, and the JavaScript code is running locally to your web browser, this option allows you to provide your own host domain. This is the same domain or domains you inserted into the two Istio VirtualService for the UI. This domain route your API calls to either the FQDN (fully qualified domain name) of the Service A Kubernetes Service running in the dev namespace, service-a.dev.svc.cluster.local, or the test Namespace, service-a.test.svc.cluster.local.

You can also use performance testing tools to load-test the platform. Many issues will not show up until the platform is under load. I recently starting using hey, a modern load generator tool, as a replacement for Apache Bench (ab), Unlike ab, hey supports HTTP/2 endpoints, which is required to test the platform on GKE with Istio. Below, I am running hey directly from Google Cloud Shell. The tool is simulating 25 concurrent users, generating a total of 1,000 HTTP/2-based GET requests to Service A.

Troubleshooting

If for some reason the UI fails to display, or the call from the UI to the API fails, and assuming all Kubernetes and Istio resources are running on the GKE cluster (all green), the most common explanation is usually a misconfiguration of the following resources:

Your four Cloud DNS records are not correct. They are not pointing to the load balancer’s front-end IP address;
You did not configure the four Kubernetes VirtualService resources with the correct subdomains;
The GKE-based microservices cannot reach the external MongoDB Atlas and CloudAMQP RabbitMQ clusters. Likely, the Kubernetes Secret is constructed incorrectly, or the two ServiceEntry resources contain the wrong host information for those external clusters;

I suggest starting the troubleshooting by calling Service A, the API’s edge service, directly, using cURL or Postman. You should see a JSON response payload, similar to the following. This suggests the issue is with the UI, not the API.

Next, confirm that the four MongoDB databases were created for Service D, Service, F, Service, G, and Service H. Also, confirm that new documents are being written to the database’s collections.

Next, confirm new the RabbitMQ queue was created, using the CloudAMQP RabbitMQ Management Console. Service D produces messages, which Service F consumes from the queue.

Lastly, review the Stackdriver logs to see if there are any obvious errors.

Part Two

In part two of this post, we will explore each observability tool, and see how they can help us manage our GKE cluster and the reference platform running in the cluster.

Since the cluster only takes minutes to fully create and deploy resources to, if you want to tear down the GKE cluster, run the part6_tear_down.sh script.

All opinions expressed in this post are my own and not necessarily the views of my current or past employers or their clients.

GCP, GKE, Go, Go-lang, Google Cloud Platform, Grafana, Istio, Jaeger, Kiali, Kubernetes, Logging, Metrics, Microservices, Observability, Prometheus, Telemetry, Zipkin

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