Image Stream

• Image Stream
  • Automatic trigger deployment

Image stream is an abstraction to container image in image registry. Image stream itself does not container any image it just a referece to actual image.

You can configure builds and deployments to watch an image stream for notifications when new images are added and react by performing a build or deployment, respectively.

Automatic trigger deployment

• import image with schedule update ( Default is every 15 minutes)

  oc import-image backend  --scheduled --confirm --all --from quay.io/voravitl/backend
  oc get istag
  

• Setup image lookup for backend imagestream

  oc set image-lookup backend
  oc set image-lookup --list
  

• With image lookup is enabled. Imagestream name can be used in deployment

      spec:
        containers:
        - name: backend
          image: backend:v1
  

• Check for latest update interval imagestream

  oc get istag backend:v1
  

  Output

  NAME         IMAGE REFERENCE                                                                                    UPDATED
  backend:v1   quay.io/voravitl/backend@sha256:19ef0afb88a1ce5d6a4422c7ab8395eb05b672fc27d5d387d9fcd8e15a44c5d7   30 seconds ago
  

• Deploy application

  oc apply -f backend.yaml
  

• Set trigger

  oc set triggers deployment/backend --from-image backend:v1 -c backend
  

  Trigger will set following annotation to deployment for container name backend

  metadata:
    name: backend
    annotations:
      image.openshift.io/triggers: '[{"from":{"kind":"ImageStreamTag","name":"backend:v1"},"fieldPath":"spec.template.spec.containers[?(@.name==\"backend\")].image"}]'
  

• When image on image registry