Kubernetes ft. Spring Boot (Series) - Monitoring with Istio #3

I know, I know.. YAML configuration is so fun, but have you ever heard of Kiali?

Brief

After we deployed the applications to the Kubernetes cluster and saw the power of its concepts in action (deployment, service, etc.) and how we can manage our services inside the cluster. We'll add another framework into the picture. Enter Istio.

Implementation

Istio - definition

Istio is a service mesh that gets applied over the Kubernetes cluster and enables us to get observability, monitoring, and traffic management over our applications.

Istio - installation

I'll keep it really short, with the emphasis on 'really' and even more on 'short'. Straight from the official website installation guide:

1. $ curl -L https://istio.io/downloadIstio | sh -         // get the latest istio release binary
2. cd istio-1.12.1       // go to downloaded folder ( in this example 1.12.1 is the version downloaded)
3. export PATH=$PWD/bin:$PATH             // add the istioctl client to the path
4. istioctl install -y           // install istio components
5. kubectl label namespace default istio-injection=enabled    // this label is needed so the envoy proxy gets added to every pod in the default namespace

After getting through with the installation you should see a few pods installed to the istio-system namespace inside the cluster:

Finally, we need to scale down our deployments to zero and then rescale it again to any number of instances you like. The reasoning for this is that Istio, although installed in our cluster, it won't apply to already running pods.

That being said, after rescaling the deployment, each pod will have now two containers: the application and the envoy proxy added by Istio. To check this, you can run:

1. kubectl get pods  // to get the pods' names. This will return a list like:

2.  kubectl get pods app-caller-dep-6cc45d765b-kmtst  -o jsonpath="{.spec.containers[*].name}"   // to get the containers' names from a specific pod. The result will be: app-caller istio-proxy

Istio - 'addons'

In order to have a visual control plane we need to add two plugins to Istio: Kiali and Prometheus.

• Kiali

  1. get the Kiali yaml file with all its components https://raw.githubusercontent.com/istio/istio/release-1.12/samples/addons/kiali.yaml

  2. for our Minikube cluster we need to change this file a little. Search for the Service definition and we'll need to change its type to a NodePort so we can access it from outside of our cluster

  3. the file should look something like this:

     apiVersion: v1
     kind: Service
     metadata:
       labels:
         app: kiali
         app.kubernetes.io/instance: kiali
         app.kubernetes.io/managed-by: Helm
         app.kubernetes.io/name: kiali
         app.kubernetes.io/part-of: kiali
         app.kubernetes.io/version: v1.42.0
         helm.sh/chart: kiali-server-1.42.0
         version: v1.42.0
       name: kiali
       namespace: istio-system
     spec:
       ports:
       - name: http
         port: 20001
         protocol: TCP
         targetPort: 20001
         nodePort: 30001
       - name: http-metrics
         protocol: TCP
         port: 9090
       selector:
         app.kubernetes.io/instance: kiali
         app.kubernetes.io/name: kiali
       sessionAffinity: None
       type: NodePort 
       
     

  4. install using the updated file: kubectl apply -f updated-kiali.yaml

• Prometheus
  • install using the Prometheus yaml file: kubectl apply -f https://raw.githubusercontent.com/istio/istio/release-1.12/samples/addons/prometheus.yaml

Kiali console

Accessing the visual console of Kiali is as easy as:

1. running minikube ip to get the ip of the local cluster ( e.g. 192.168.64.7)
2. open a browser and go to 192.168.64.7:30001 ( 30001 - Kiali's exposed port)

As you can see, Kiali provides a nice picture of the applications in our cluster, and the way they communicate with each other.

Bonus

Other than just showing the apps, communication between them and other traffic data, Kiali has some more really useful features.

Let's look at how we can play around with traffic rules between applications directly from Kiali's control plane.

1. Go to Graph tab.
2. Right-click on the app-receiver-dep service and choose Show details.
3. Click on Actions dropdown and select Fault injection .
4. Check Add HTTP Abort and choose any HTTP error code this service should respond with.
5. Check with a Postman Request.