Posts Tagged Metrics

Kubernetes-based Microservice Observability with Istio Service Mesh: Part 2

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.

Golang Service Diagram with Proxy v2.png

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 of 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.

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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.

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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.

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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

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.

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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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

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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.

screen_shot_2019-03-19_at_11_01_26_pm

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.

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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.

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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.

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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.

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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.
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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.

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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.

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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.

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

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

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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.

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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%.

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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.

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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.

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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.

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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.

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Kubernetes-based Microservice Observability with Istio Service Mesh: Part 1

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.

Golang Service Diagram with Proxy v2

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).

Golang Service Diagram with Proxy v2 res

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.

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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.

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.

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.
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Set-up and Installation

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

  1. Create the MongoDB Atlas database cluster;
  2. Create the CloudAMQP RabbitMQ cluster;
  3. Modify the Kubernetes resources and scripts for your own environments;
  4. Create the GKE cluster on GCP;
  5. Deploy Istio 1.1.0 to the GKE cluster, using Helm;
  6. Create DNS records for the platform’s exposed resources;
  7. Deploy the Go-based microservices, Angular UI, and associated resources to GKE;
  8. Test and troubleshoot the platform;
  9. 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.

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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.

screen_shot_2019-03-09_at_5_44_33_pm

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.

screen_shot_2019-03-09_at_5_47_57_pm

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.

screen_shot_2019-03-09_at_5_58_35_pm

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

screen_shot_2019-03-09_at_5_59_14_pm

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.screen_shot_2019-03-09_at_5_49_37_pm

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.

screen_shot_2019-03-09_at_5_57_20_pm

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.

screen_shot_2019-03-09_at_5_56_29_pm

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.

screen_shot_2019-03-09_at_6_01_29_pm

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.

screen_shot_2019-03-10_at_10_48_49_pm

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.

screen_shot_2019-03-09_at_6_12_59_pm

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

screen_shot_2019-03-09_at_6_03_02_pm

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.

screen_shot_2019-03-09_at_6_13_16_pm

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.

screen_shot_2019-03-19_at_8_43_10_pm

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.

screen_shot_2019-03-17_at_12_02_22_pm.png

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.

screen_shot_2019-03-19_at_8_53_47_pm

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:

  1. Your four Cloud DNS records are not correct. They are not pointing to the load balancer’s front-end IP address;
  2. You did not configure the four Kubernetes VirtualService resources with the correct subdomains;
  3. 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.

screen_shot_2019-03-17_at_12_06_27_pm.png

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.

screen_shot_2019-03-17_at_11_55_19_am

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.

screen_shot_2019-03-09_at_6_22_08_pm

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

screen-shot-2019-03-08-at-4_44_03-pm

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.

screen_shot_2019-03-09_at_11_38_34_pm

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.

screen_shot_2019-03-10_at_10_58_55_pm.png

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

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