Automatically init rolling update of kubernetes deployment when there is a new version of container image

Question

I have a kubernetes deployment that looks like this:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: datacollector
spec:
  replicas: 1
  selector:
    matchLabels:
      pod-type: datacollector
  template:
    metadata:
      labels:
        pod-type: datacollector
    spec:
      imagePullSecrets:
      - name: secret
      containers:
        - name: datacollector
          image: "build.dorangg.dev/doranggdatacollector:latest"
          imagePullPolicy: Always

Currently I run the following command whenever I want to update the deployment to use the newest version of the image from the docker registry (build.dorangg.dev) :

kubectl rollout restart deployment/datacollector

I want to initiate a rolling update of the deployment (what the above command does) AUTOMATICALLY whenever a new version of the image appears in the docker registry.

Can this be accomplished using the kubernetes configuration? If not, is this automation possible to do with a script?

score 0 · Answer 1 · answered Jul 15 '21 at 04:30

The better way to do this is to use kubectl set image to tell the deployment there is a new image, but it won't work if you are using :latest because the deployment won't trigger if the tag doesn't change. It's bad idea using :latest in general anyway, so you would have to move to semversioning of the tags for your containers.

score 0 · Answer 2 · answered Aug 19 '19 at 15:32

Can this be accomplished using the kubernetes configuration?

I don't know.

If not, is this automation possible to do with a script?

Yes. You do a docker pull on the image. If docker pulls a new image then you delete the POD with kubectl and then it gets redeployed.

score 0 · Answer 3 · answered Aug 21 '19 at 14:48

Honestly I don't think it can be configured inside the Kubernetes. It will need additional scripts/triggers.

Options comes to my mind, but you need to "catch" new of the new image with script (for example name of new image after successfull push to repository).

- Patch deployment

$ kubectl patch deployment [your-deployment] -p \
'{"spec":{"template":{"spec":{"image":"[new-image-name:tag]"}}}}'

Kubernetes if will see some changes it should redeploy whole deployment.

- Create script with set new image

$ kubectl set image deployment/[deployment-name] [image-name]=[new-image-name:tag]

After this change kubernetes should also redeploy all pods.

- Use HELM

As helm using Charts and Templates you can create script which will change image name in values.yaml and redeploy it.

- Patch GracePeriod

If you want to keep the same image name all the time, you can try to patch GracePeriod. It was described here.

Hope it will help.

Automatically init rolling update of kubernetes deployment when there is a new version of container image

3 Answers3