kubernetes-image-updater

When CI finishes build of new container, test environment(s) should update automatically. However there isn't out of box support for this kind of feature in either kubernetes or any common registery. It's common to update test environments directly from build scripts with command like kubectl set image deployment/image-$branch image-$branch=$published.image:$published.tag --namespace=something.

However this raises many issues:

• When multiple projects use same container (which is common case) they need to reconfigure existing CI pipeline for shared container to update everything.
• What happens if you delete old project namespace from testing environment? Build will fail...
• Unnecessary boilerplate.

How it works

When event about updated image arrives, scan current cluster through for matching images and if any is found, then update image to current version.

Service gives http callback apis which are easy to integrate to most systems via hooks. Theres also possibility to integrate this directly with GCR registry with pub events and functions, however we don't use them so there are no 'ready to use' examples available.

Running in kubernetes

Software uses kuberetes 'InClusterConfiguration' model and has access for it's current cluster.

apiVersion: v1
kind: Deployment
metadata:
  name: image-updater
  namespace: your-namespace
  labels:
    app: image-updater
spec:
  replicas: 1
  template:
    metadata:
      labels:
        name: image-updater
    spec:
      containers:
      - image: ptcos/kubernetes-image-updater:latest
        imagePullPolicy: Always
        name: image-updater

Setting up development environment

Open kubectl proxy to connect targeted testing cluster.

kubectl proxy

Run application with development configuration.

dotnet run --environment=Development

Navigate to http://localhost:5000/doc/.