BLT Best Deployment

Example K8s deployment that does automated rollback.

The project

This project is a very simple node application. In order to avoid building a docker artifact the index.js is inside of our configmap infra/deployment-cm.yaml

The index.js will return 500 if the env var FAIL_REQUEST is set to true.

Ensuring readiness

First, in order to do this it is important that your application has valid readinessProbes attached to it. We don't want Kubernetes to think the deployment was successful because your container takes a second to load and realize it's failing.

Verifying deployment

With your readinessProbe equiped, we can then use the kubectl rollout status command to watch the deployment.

By default, status will watch the status and exit upon successful completion. Since it's hard to tell what a failure is, we rely on timing out using timeout. In this example we wait for 1 min.

Conclusion

With our rollout status check as a target step in our Makefile, the error will propagate up to our Travis build so we're notified of the deployment failure.