--- title: "Traffic management with Istio on OVHcloud Managed Kubernetes" description: "Find out how to manage traffic with Istio on OVHcloud Managed Kubernetes" url: https://docs.ovhcloud.com/de/guides/public-cloud/containers-orchestration/managed-kubernetes/traffic-management-istio lang: de lastUpdated: 2021-09-22 --- # Traffic management with Istio on OVHcloud Managed Kubernetes [Istio](https://istio.io) is a open source service mesh and platform to reduce the complexity of deploying, securing, controlling and observing distributed services. As the Istio site explains, Istio helps you to: - Control the flow of traffic between services - Secure the services and manage the authentication, authorization and encryption of inter-service communications - Apply and enforce policies on distributes services - Monitor the services gathering metrics, logs and traces In this tutorial we are showing some of the traffic management features of Istio, and how you can use them on your OVHcloud Managed Kubernetes cluster. ## Before you begin This tutorial presupposes that you already have a working OVHcloud Managed Kubernetes cluster, and some basic knowledge of how to operate it. If you want to know more on those topics, please look at the [deploying a Hello World application](/de/guides/public-cloud/containers-orchestration/managed-kubernetes/deploy-hello-world.md) documentation. It also supposes you have a basic knowledge of Istio, and that you have installed it in your Kubernetes cluster. If it isn't the case, please follow the [Installing Istio on OVHcloud Managed Kubernetes](/de/guides/public-cloud/containers-orchestration/managed-kubernetes/install-istio.md) tutorial. We are going to use the [Bookinfo](https://istio.io/docs/examples/bookinfo/) example application, as we did in that tutorial, so if you haven't installed it, please do it now. ## Preparing the Bookinfo app Before you can use Istio to control the Bookinfo version routing, you need to define the available versions, called `subsets`, in [destination rules](https://istio.io/docs/concepts/traffic-management/#destination-rules). Go to your Istio install folder and apply the `DestinationRules` for Bookinfo: ```bash kubectl -n istio-apps apply -f samples/bookinfo/networking/destination-rule-all-mtls.yaml ``` Then wait a few moments to for the destination rules to propagate and verify them: ```bash kubectl -n istio-apps get destinationrules -o yaml ``` In the case of my example cluster: ```console $ kubectl -n istio-apps apply -f samples/bookinfo/networking/destination-rule-all-mtls.yaml destinationrule.networking.istio.io/productpage created destinationrule.networking.istio.io/reviews created destinationrule.networking.istio.io/ratings created destinationrule.networking.istio.io/details created $ kubectl -n istio-apps get destinationrules -o yaml apiVersion: v1 items: - apiVersion: networking.istio.io/v1beta1 kind: DestinationRule metadata: annotations: kubectl.kubernetes.io/last-applied-configuration: | {"apiVersion":"networking.istio.io/v1beta1","kind":"DestinationRule","metadata":{"annotations":{},"name":"details","namespace":"istio-apps"},"spec":{"host":"details","subsets":[{"labels":{"version":"v1"},"name":"v1"},{"labels":{"version":"v2"},"name":"v2"}],"trafficPolicy":{"tls":{"mode":"ISTIO_MUTUAL"}}}} creationTimestamp: "2021-09-21T15:00:57Z" generation: 1 name: details namespace: istio-apps resourceVersion: "524439454" uid: 10b370f0-f1a8-4830-bb9f-458c77b1c03d spec: host: details subsets: - labels: version: v1 name: v1 - labels: version: v2 name: v2 trafficPolicy: tls: mode: ISTIO_MUTUAL [...] ``` ## A/B Testing with Istio [A/B Testing](https://en.wikipedia.org/wiki/A/B_testing) is used when we want to try two different versions of an application and compare user interaction and engagement to choose the best one. It requires to be able to push the two versions into production at the same time, split traffic between the two versions, and collect metrics to be able to do an informed choice. A/B Testing used to be a difficult problem with traditional deployment methods, and it's very hard to do it directly in Kubernetes since there is no notion of versions, but Istio make it rather simple. Let's use the Bookinfo application to show how easily you can do A/B Testing on Kubernetes with Istio. The Bookinfo application composed of four separate microservices: - `productpage`: it calls the `reviews` and `details` service and build the page - `reviews`: it contains with book reviews, and it calls the `rating` service - `details`: it contains the book information - `ratings`: it contains the book rating information To setup A/B Testing on Bookinfo we are using the `reviews` microservice, as it has three versions: - `v1`: it doesn't call the `ratings` service - `v2`: it calls the `ratings` service and displays the rating as black stars - `v3`: it calls the `ratings` service and displays the rating as red stars ![Bookinfo architecture](/images/public-cloud/containers-orchestration/managed-kubernetes/traffic-management-with-istio/bookinfo-architecture.png) By default, the Bookinfo install deploys the three versions without explicit routing definitions. Istio then routes the requests to all available versions of `reviews` in a round robin fashion, so sometimes the book review output contains star ratings and other times it does not. Let's say we want to send 50% of traffic to `v2` and get the black stars, and the other 50% to `v3` and its red stars. We can create a `VirtualService` to define this behavior: ```yaml apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: reviews spec: hosts: - reviews http: - route: - destination: host: reviews subset: v2 weight: 50 - destination: host: reviews subset: v3 weight: 50 ``` Write down the `VirtualService` into a `reviews-50-v2-50-v3.yaml` file and apply it: ```bash kubectl apply -n istio-apps -f reviews-50-v2-50-v3.yaml ``` and confirm that the rule is created: ```bash kubectl -n istio-apps get virtualservice reviews -o yaml ``` In the case of my example cluster: ```console $ kubectl apply -n istio-apps -f ./reviews-50-v2-50-v3.yaml virtualservice.networking.istio.io/reviews created $ kubectl -n istio-apps get virtualservice reviews -o yaml apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: [...] spec: hosts: - reviews http: - route: - destination: host: reviews subset: v2 weight: 50 - destination: host: reviews subset: v3 weight: 50 ``` Now, on the `/productpage` of the Bookinfo app (accessing through `http://$GATEWAY_URL/productpage` URL), at every refresh you will see that stars change alternatively between back (`v2`) and red (`v3`). ![A/B Testing - At every refresh you will see that stars change alternatively between back (`v2`) and red (`v3`)](/images/public-cloud/containers-orchestration/managed-kubernetes/traffic-management-with-istio/ab-testing-001.png) ## Canary Testing with Istio Similar to A/B Testing, [Canary Testing](https://whatis.techtarget.com/definition/canary-canary-testing) is pushing a new version of a service to a small group of users. The idea is to test the new release, progressively, in a reduced number of real-world users, to quickly discovering potential bugs while minimizing the number of users impacted. The strategy is called Canary Testing because canaries were once used in coal mining to alert miners when toxic gases reached dangerous levels. Like the canary in a coal mine, the end user who is selected to receive the new release is unaware he is being used to provide an early warning. Doing Canary Testing on Kubernetes with Istio is similar to A/B Testing. ![Canary Release v1 to v2 progressing release](/images/public-cloud/containers-orchestration/managed-kubernetes/traffic-management-with-istio/canary-schema.png) Let's begin by redirecting all the `reviews` traffic to `v1`, it will be our stable release: ```yaml apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: reviews spec: hosts: - reviews http: - route: - destination: host: reviews subset: v1 weight: 100 ``` Write down the `VirtualService` into a `reviews-all-v1.yaml` file and apply it: ```bash kubectl apply -n istio-apps -f reviews-all-v1.yaml ``` and confirm that the rule is created: ```bash kubectl -n istio-apps get virtualservice reviews -o yaml ``` At this moment all the traffic goes to the `v1` version of reviews, without ratings: ![Canary Testing - all traffic to v1](/images/public-cloud/containers-orchestration/managed-kubernetes/traffic-management-with-istio/canary-testing-001.png) Now let's say we want to send the `v2` to 5% of the traffic. We simply define the new behavior in a YAML file: ```yaml apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: reviews spec: hosts: - reviews http: - route: - destination: host: reviews subset: v1 weight: 90 - destination: host: reviews subset: v2 weight: 10 ``` Write down the `VirtualService` into a `reviews-90-v1-10-v2.yaml` file and apply it: ```bash kubectl -n istio-apps apply -f reviews-90-v1-10-v2.yaml ``` and confirm that the rule is created: ```bash kubectl -n istio-apps get virtualservice reviews -o yaml ``` Now, on the `/productpage` of the Bookinfo app, 9 times out of 10 you will get the `v1`, without ratings, and 1 out of 10 times you will get the `v2`, with black stars. ![Canary Testing - one tenth of times we get v2](/images/public-cloud/containers-orchestration/managed-kubernetes/traffic-management-with-istio/canary-testing-002.png) ## Rolling Deployments and Blue/Green Deployments Both [Rolling Deployments](https://searchitoperations.techtarget.com/definition/rolling-deployment) and [Blue/Green Deployments](https://en.wikipedia.org/wiki/Blue-green_deployment) are deployment strategies to ensure that new releases can be shipped without any downtime. ![Rolling Deployment](/images/public-cloud/containers-orchestration/managed-kubernetes/traffic-management-with-istio/rolling-deployment-001.png) Doing a Rolling Deployment on Istio is rather simple, you can take as base the examples of Canary Testing and A/B Testing. Let's apply again the `reviews-all-v1.yaml` file to redirect all the `reviews` traffic to the `v1`: ```bash kubectl -n istio-apps apply -f reviews-all-v1.yaml ``` The `v1` is our initial release. Let's say we want to ship `v2` as new release, but using Rolling Deployment to be sure there is no downtime. The easiest way would be pass by an intermediate state where traffic is split 50%-50% between `v1` and `v2`: ```yaml apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: reviews spec: hosts: - reviews http: - route: - destination: host: reviews subset: v1 weight: 50 - destination: host: reviews subset: v2 weight: 50 ``` Write down the `VirtualService` into a `reviews-50-v1-50-v2.yaml` file and apply it: ```bash kubectl -n istio-apps apply -f reviews-50-v1-50-v2.yaml ``` At this moment traffic will be equally split between the two releases of `reviews`. ![Rolling deployment - At this moment traffic will be equally split between the two releases of `reviews`](/images/public-cloud/containers-orchestration/managed-kubernetes/traffic-management-with-istio/rolling-deployment-002.png) If everything is correct, we can safely route all the traffic to `v2`: ```yaml apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: reviews spec: hosts: - reviews http: - route: - destination: host: reviews subset: v2 weight: 100 ``` Write down the `VirtualService` into a `reviews-all-v2.yaml` file and apply it: ```bash kubectl -n istio-apps apply -f reviews-all-v2.yaml ``` And now the `v2` of `reviews` receives all the traffic, and our Rolling Deployment is completed. ![Rolling deployment - And now the `v2` of `reviews` receives all the traffic](/images/public-cloud/containers-orchestration/managed-kubernetes/traffic-management-with-istio/rolling-deployment-003.png) ## What's next? Now you have seem some of the traffic management capabilities of Istio, you can explore other [examples of Istio traffic management](https://istio.io/docs/tasks/traffic-management/): [fault injection](https://istio.io/docs/tasks/traffic-management/fault-injection/), [circuit breaking](https://istio.io/docs/tasks/traffic-management/circuit-breaking/), [mirroring](https://istio.io/docs/tasks/traffic-management/mirroring/)... ## Go further - If you need training or technical assistance to implement our solutions, contact your sales representative or click on [this link](https://www.ovhcloud.com/de/professional-services/) to get a quote and ask our Professional Services experts for assisting you on your specific use case of your project. - Join our [community of users](https://community.ovhcloud.com/).