Performing a Rolling Update

We’ll assume the new version of the app has already been created and containerized as a Docker image with the edge tag. All that is left to do is use Kubernetes to push the update to production. For this example, we’re ignoring real-world CI/CD workflows and version control tools.

The first thing you need to do is update the image tag used in the Deployment’s manifest file. The initial version of the app used an image tagged as nigelpoulton/k8sbook:latest. You’ll update the .spec.template.spec.containers section of the Deployment manifest to reference the new nigelpoulton/k8sbook:edge image. This will ensure that next time the manifest is POSTed to the API server, all Pods in the Deployment will be replaced with new ones running the new edge image.

The following is the updated deploy.yml manifest file – the only change is to .spec.template.spec.containers.image, indicated by the commented line.