Thursday, March 21, 2019

Installing Istio and Bookinfo Application on K8S

In this blog previously we explored the different ways of getting started with K8S using Play-With-Kubernetes, Minikube and finally easily installing K8S using a combination of VirtualBox and Vagrant.

Now we will try to install Istio on top of the existing K8S setup and install a Microservices based application called Bookinfo on top of it. Once the setup of Istio is done, we should be able to explore the different features of Istio. The Bookinfo Application is a polygot application using Python, Java, Ruby and NodeJS. The various Microservices and how there interact is detailed here.

So, what is service mesh and what is Istio? Istio is an Open Source implementation of service mesh. While K8S provides orchestration of the Containers, Istio is used for the management of the services created by these Containers in the Microservices based Architecture. More about Istio and service mesh here (1, 2, 3). As we explore the different features of Istio in the upcoming blogs, it will be more clear what service mesh is all about in the context of Microservice based architecture.

Istio is not the only implementation of service mesh as mentioned here. Google uses Istio, while AWS uses App Mesh. Both of them are built on top of Envoy proxy.

Lets jump into the installation of Istio and the Bookinfo Microservices based application on top of it. We would be following the steps mentioned here and here.

Step 1: Download Istio using the 'curl -L https://git.io/getLatestIstio | ISTIO_VERSION=1.1.0 sh -' command. It will create a 'istio-1.1.0' folder with the below structure.


Step 2: Install the Istio CRD using the `for i in install/kubernetes/helm/istio-init/files/crd*yaml; do kubectl apply -f $i; done` command.



Step 3: Install the Istio binaries using the 'kubectl apply -f install/kubernetes/istio-demo-auth.yaml' command.



Step 4: Verify the Istio installation using 'kubectl get svc -n istio-system' and 'kubectl get pods -n istio-system' commands. All the services should be created and the pods should be in a Running or Completed status below.

Now we are done with the Istio setup. Note there are a couple of different ways of installing Istio, but this is the easiest way.



Step 5: Run the below commands to create a namespace called 'my-namespace' and make it the default namespace in the current context. The current context name 'kubernetes-admin@kubernetes' in the third command has to be modified based on the output of the second command.

a) kubectl delete namespaces my-namespace;kubectl create namespace my-namespace
b) kubectl config current-context
c) kubectl config set-context kubernetes-admin@kubernetes --namespace=my-namespace


Step 6: Istio sidecar can be injected into the application manually or automatically. We will look at the automatic way. Label the namespace with the 'kubectl label namespace my-namespace istio-injection=enabled' command. With this label, any application deployed in this namespace will have Istio sidecar injected into it automatically.


Step 7: Deploy the Bookinfo application using the 'kubectl apply -f samples/bookinfo/platform/kube/bookinfo.yaml' command. Make sure to be the Istio folder as shown below.


Check the status of the pods (kubectl get pods), they should be in the Running status after a few minutes.


To confirm that the application is running. Make a call to the Bookapp webpage from one of the pod. using the below command.

kubectl exec -it $(kubectl get pod -l app=ratings -o jsonpath='{.items[0].metadata.name}') -c ratings -- curl productpage:9080/productpage | grep -o "<title>.*</title>"

The output should be as shown below. This means that the application has been deployed successfully. Note that is says 2/2 in the above screenshot. Why is it so? One is main application container and the other is Envoy proxy container injected by Istio. Without the label on the namespace it should say 1/1 as the Envoy proxy container is not injected by Istio.


Step 8: An overlay network is created by default and the Bookinfo webpage is only accessible within this network and not from the outside. For this we have to use port forwarding using the 'kubectl port-forward --address 0.0.0.0 pod/productpage-v1-6b6798cb84-v6l7p 1234:9080' command. In this the pod name should be changed, which can be got by running the 'kubectl get pods' command.


Instead of using port forwarding we should have used Istio Gateway as mentioned here, But, this automatically creates a load balancer which is not possible in the local machine, but only on the Cloud. So, we are using port forwarding as mentioned above.

Step 9: Now the Bookinfo webpage can be accessed from the browser (192.168.0.101:1234/productpage). Note that the IP address has to be modified to match the IP address of any of the node in the K8S cluster.


Step 10: Use the below commands to cleanup the Bookinfo application and Istio.

samples/bookinfo/platform/kube/cleanup.sh

kubectl delete -f install/kubernetes/istio-demo-auth.yaml
for i in install/kubernetes/helm/istio-init/files/crd*yaml; do kubectl delete -f $i; done




Conclusion


In this blog we looked at the required steps for installation Istio and then Bookinfo application on top of K8S. It's not too difficult to install Istio as mentioned above, but the Cloud vendors providing managed K8S make it even easier with a single click installation of Istio or any other service mesh.

In the future blogs, we will explore the different features of Istio in a bit more detail using the Bookinfo or some other application, this will make it clear what Istio and service mesh is all about.

No comments:

Post a Comment