Trigger build in OpenShift on change in Gitlab container registry

I am having a trouble to figure out how OpenShift can trigger deployment based on change in GitLab container registry. I have configured option in OpenShift called Deploy an existing Image from an Image Stream or Image registry. This works and I can see my pod up and running. When I tried updating docker image and pushed to GitLab container registry, I did not see any new deployment in OpenShift. Please guide.

Thanks!!

Solution

OpenShift can automatically trigger redeployment on an image update, but only if the image changes in an ImageStreamTag resource on the same cluster.

The image.openshift.io/triggers annotation can be configured in the deployment to reference an ImageStreamTag on the local cluster.

In the following example, the Deployment will be triggered by an update of the -n ci imagestreamtag mirror:latest tag.

apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    image.openshift.io/triggers: '[{"from":{"kind":"ImageStreamTag","name":"content-mirror:latest","namespace":"ci"},"fieldPath":"spec.template.spec.containers[?(@.name==\"mirror\")].image"}]'
  name: base-4-10
  namespace: app
spec:
...

To achieve the same thing, you can either:

Push directly to the cluster registry

Establish an ImageStream resource in your cluster and push your image there instead of the GitLab container registry. Configure your Deployment to be reactive to changes to the tag you push the image to.

Periodically import the image from GitLab into an ImageStream

ImageStreams can be configured to periodically import external images. The import happens every 15 minutes.

Create a new ImageStream like app-images.
Tag your GitLab image into the ImageStream like: oc tag docker.io/app:latest app-images:app --scheduled
Configure your Deployment's image.openshift.io/triggers annotation to be reactive to the app-images:myapp ImageStreamTag.