Istio 101 (0.8.0) on GKE

In one of my previous posts, I showed how to install Istio on minikube and deploy the sample BookInfo app. A new Istio version is out (0.8.0) with a lot of changes, especially changes on traffic management, which made my steps in the previous post a little obsolete.

In this post, I want to show how to install Istio 0.8.0 on Google Kubernetes Engine (GKE), deploy the sample BookInfo app and show some of the add-ons and traffic routing.

Create Kubernetes cluster

First, we need a Kubernetes cluster to install Istio. On GKE, this is a single command:

gcloud container clusters create hello-istio \
 --cluster-version=latest \
 --zone europe-west1-b \
 --num-nodes 4

I’m using 4 worker nodes. That’s the recommended number of nodes for BookInfo sample.

Once the cluster is created, we also need to create a clusterrolebinding for Istio to be able to manage the cluster:

kubectl create clusterrolebinding cluster-admin-binding \
 --clusterrole=cluster-admin \
 --user=$(gcloud config get-value core/account)

Download & Setup Istio

Now that we have a cluster, let’s download the latest Istio (0.8.0 as of today):

curl -L https://git.io/getLatestIstio | ISTIO_VERSION=0.8.0 sh -

Add Istio’s command line tool istioctl to your PATH. We’ll need it later:

export PATH="$PATH:./istio-0.8.0/bin"

Install Istio

It’s time to install Istio with mutual authentication between sidecars:

kubectl apply -f install/kubernetes/istio-demo-auth.yaml

Once it’s done, you can check that pods are running under istio-system namespace:

kubectl get pods -n istio-system

You’ll realize that in addition to Istio base components (eg. pilot, mixer, ingress, egress), a number of add-ons are also installed (eg. prometheus, servicegraph, grafana). This is different from the previous versions of Istio.

Enable sidecar injection

When we configure and run the services, Envoy sidecars can be automatically injected into each pod for the service. For that to work, we need to enable sidecar injection for the namespace (‘default’) that we will use for our microservices. We do that by applying a label:

kubectl label namespace default istio-injection=enabled

And verify that label was successfully applied:

kubectl get namespace -L istio-injection

Deploy BookInfo app

Let’s deploy the BookInfo sample app now:

kubectl apply -f samples/bookinfo/kube/bookinfo.yaml

And make sure all the pods are running. Notice that there are 2 pods for each service (1 the actual service and 1 sidecar):

kubectl get pods

Deploy BookInfo Gateway

In Istio 0.8.0, traffic management completely changed and one of those changes is that you need to create a gateway for ingress traffic. Let’s go ahead and create a gateway for BookInfo app:

istioctl create -f samples/bookinfo/routing/bookinfo-gateway.yaml

Use BookInfo app

We can finally take a look at the app. We need to find ingress gateway IP and port:

kubectl get svc istio-ingressgateway -n istio-system

To make it easier for us, let’s define a GATEWAY_URL variable:

export INGRESS_HOST=$(kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
export INGRESS_PORT=$(kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="http")].port}')
export GATEWAY_URL=$INGRESS_HOST:$INGRESS_PORT

Let’s see if the app is working. You should get 200 with curl:

curl -o /dev/null -s -w "%{http_code}\n" http://${GATEWAY_URL}/productpage

You can also open a browser and see the web frontend for product page. At this point, we got the app deployed and managed by a basic installation of Istio.

Next, we’ll take a look at some of the add-ons. Unlike previous versions, add-ons are automatically installed already. Let’s start sending some traffic first:

for i in {1..100}; do curl -o /dev/null -s -w "%{http_code}\n" http://${GATEWAY_URL}/productpage; done

Grafana dashboard

There’s Grafana for dashboarding. Let’s setup port forwarding first:

kubectl -n istio-system port-forward $(kubectl -n istio-system get pod -l app=grafana -o jsonpath='{.items[0].metadata.name}') 8080:3000

Navigate to http://localhost:8080 to see the dashboard:

Istio Dashboard in Grafana

Prometheus metrics

Next, let’s take a look at Prometheus for metrics. Set port forwarding:

kubectl -n istio-system port-forward $(kubectl -n istio-system get pod -l app=prometheus -o jsonpath='{.items[0].metadata.name}') 8083:9090

Navigate to http://localhost:8083/graph to see Prometheus:

Prometheus in Istio

ServiceGraph

For dependency visualization, we can take a look at ServiceGraph:

kubectl -n istio-system port-forward $(kubectl -n istio-system get pod -l app=servicegraph -o jsonpath='{.items[0].metadata.name}') 8082:8088

Navigate to http://localhost:8082/dotviz:

Screen Shot 2018-06-07 at 10.02.38 AM.png

Tracing

For HTTP tracing, there is Jaegar and Zipkin. Let’s take a look at Jaeger. Setup port forwarding as usual:

kubectl port-forward -n istio-system $(kubectl get pod -n istio-system -l app=jaeger -o jsonpath='{.items[0].metadata.name}') 8084:16686

Navigate to http://localhost:8084

Screen Shot 2018-06-07 at 10.05.11 AM

Traffic Management

Traffic Management changed dramatically in 0.8.0. You can read more about it here but basically instead of routing rules, we now have VirtualServices and DestinationRules.

You can see the existing VirtualServices and DestinationRules like this:

istioctl get virtualservices -o yaml
istioctl get destinationrules -o yaml

When you go to the product page of BookInfo application and do a browser refresh a few times, you will see that the reviews section on the right keeps changing (the stars change color). This is because there are 3 different reviews microservices and everytime, a different microservice is invoked. Let’s pin all microservices to version1:

istioctl create -f samples/bookinfo/routing/route-rule-all-v1-mtls.yaml

This creates VirtualServices and DestinationRules needed to pin all microservices to version1. Now, if you back to the product page and do a browser refresh, nothing changes because reviews microservice is pinned to version1 now.

To pin a specific user (eg. Jason) to a specific version (v2), we can do the following:

istioctl replace -f samples/bookinfo/routing/route-rule-reviews-test-v2.yaml

With this rule, if you login to the product page with username “Jason”, you should see the v2 version of reviews microservice.

To clean up all destination rules, run the following and now we’re back to the beginning with 3 different versions of the microservices:

istioctl delete -f samples/bookinfo/routing/route-rule-all-v1.yaml

Cleanup

This wraps up all the basic functionality of Istio 0.8.0 that I wanted to show on GKE. To cleanup, let’s first delete the BookInfo app:

samples/bookinfo/kube/cleanup.sh

Confirm that BookInfo app is gone:

istioctl get gateway
istioctl get virtualservices
kubectl get pods

Finally, cleanup Istio:

kubectl delete -f install/kubernetes/istio-demo.yaml

Confirm that Istio is gone:

kubectl get pods -n istio-system
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