Helm

Intro

During keptn install, we are installing Tiller (Helm v2.12.3) on the Kubernetes cluster. Keptn then uses Helm for deploying onboarded services to a Kubernetes cluster. This is currently implemented in Keptn’s helm-service.

Onboarding

Based on the onboarding the carts service tutorial we will describe the two different deployment types that the helm-service manages and what this does on Kubernetes level.

Those deployments are based on the provided helm-chart for the carts microservice, see https://github.com/keptn/examples/tree/0.6.2/onboarding-carts/carts for details.

Direct deployments

In case of deployment_strategy: direct (see shipyard.yaml), Helm deploys a release called sockshop-dev-carts as carts in namespace sockshop-dev.

$ kubectl get deployments -n sockshop-dev carts -owide

NAME    READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                 SELECTOR
carts   1/1     1            1           56m   carts        docker.io/keptnexamples/carts:0.11.1   app=carts

When sending a new-artifact, we are updating the helm charts values.yaml file with the respective image name.

• chart/values.yaml
• chart/templates/deployment.yaml

Blue-green deployments

In case of deployment_strategy: blue_green_service (see shipyard.yaml), Helm creates two deployments within the Kubernetes cluster: the primary and the canary deployment. This can be inspected using the following command:

$ kubectl get deployments -n sockshop-staging carts carts-primary -owide

NAME            READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                 SELECTOR
carts-primary   1/1     1            1           56m   carts        docker.io/keptnexamples/carts:0.11.1   app=carts-primary
carts           0/0     0            0            3m   carts        docker.io/keptnexamples/carts:0.11.2   app=carts

When a new artifact is deployed (e.g., 0.11.2), a canary deployment will be modified and scaled up.

NAME            READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                 SELECTOR
carts-primary   1/1     1            1           57m   carts        docker.io/keptnexamples/carts:0.11.1   app=carts-primary
carts           0/1     1            1            1m   carts        docker.io/keptnexamples/carts:0.11.2   app=carts

The primary deployment is always available (and called carts-primary). The canary deployment (called carts) gets scaled up in the case of a new-artifact event (e.g., in this case someone has sent a new-artifact for 0.11.2). Traffic is shifted to the canary release.

Once testing has finished, the primary deployment is upgraded to the new version (0.11.2).

NAME            READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                 SELECTOR
carts-primary   1/1     1            1            3m   carts        docker.io/keptnexamples/carts:0.11.2   app=carts-primary
carts           1/1     1            1            1d   carts        docker.io/keptnexamples/carts:0.11.2   app=carts

After a new pod for the primary deployment has been successfully deployed, traffic is shifted to the primary deployment and the canary deployment is scaled down:

NAME            READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES                                 SELECTOR
carts-primary   1/1     1            1            4m   carts        docker.io/keptnexamples/carts:0.11.2   app=carts-primary
carts           0/0     0            0            1d   carts        docker.io/keptnexamples/carts:0.11.2   app=carts

Clean-up after deleting a project

When executing keptn delete project PROJECTNAME (see cli docs), we do not clean up existing deployments nor helm releases. To do so, the following manual steps are necessary:

1. Delete all relevant helm releases:

   • Connect directly to the helm-service using kubectl exec -it svc/helm-service -n keptn sh
   • Execute the following command to verify that releases still exists using helm ls, e.g.:
     

   helm ls | grep sockshop
   

   Note: Take special care and double check that this command only lists the releases related to the project, and no others!

   • Delete the relevant releases using helm delete --purge, e.g.:
     

   helm delete --purge $(helm ls | grep sockshop | cut -f1 | tr '\n' ' ')
   

2. Delete all relevant namespaces:

   • For each stage defined the shipyard.yaml file, execute kubectl delete namespace PROJECTNAME-STAGENAME, e.g.:
     

   kubectl delete namespace sockshop-dev
   kubectl delete namespace sockshop-staging
   kubectl delete namespace sockshop-production