APP Example

Introduction

This chart allows you to deploy a "dummy" application that uses the ExtendedDaemonset.

Thanks to this chart you can test several ExtendedDaemonset features, such as:

• The Canary deployment strategy
• The extendeddaemonset-check util pod with the helm test command.
• The possibility to override a Pod resources for a specific Node thanks to an ExtendedDaemonsetSettings resource.

Deployment

Before deploying this chart, you should have deployed the ExtendedDaemonset Controller with the following command: helm install eds-controller ./chart/extendeddaemonset.

Now you can deploy the app-example with default values this: helm install foo ./chart/app-example.

Canary deployment

Check if a canary deployment finished

Helm3 introduces the helm test command, which can be used to validate a "complex" deployment, was looking only at the state if the pod is not enough. It is also useful when the chart contains CRDs because Helm is not aware of how to understand the status of a CRD.

This chart contains a test "Pod" (manifests present in app-example/templates/tests) that can check if a Extendedaemonset update is finished.

To simulate an update, the following command will update the docker image tag for the "foo" application: helm upgrade foo ./chart/app-example --set image.tag=stable.

The ExtendedDaemonset status should have been moved to canary

$ kubectl get eds
NAME              DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   IGNORED UNRESPONSIVE NODES   STATUS   REASON   ACTIVE RS               CANARY RS               AGE
foo-app-example   3         3         3       3            3                                        Canary            foo-app-example-db2sk   foo-app-example-76kz8   1h

With the default configuration, the Canary deployment is set to 3min. During this period only one pod has been updated.

The command helm test foo starts a Pod with a specific container that checks the ExtendedDaemonset status. The command returns when the canary deployment and the rolling-up are finished.