6.7. Working with image streams

Procedure

• Get general information about the image stream and detailed information about all the tags it is pointing to:

  $ oc describe is/<image-name>

  For example:

  $ oc describe is/python

  Example output

  Name:			python
  Namespace:		default
  Created:		About a minute ago
  Labels:			<none>
  Annotations:		openshift.io/image.dockerRepositoryCheck=2017-10-02T17:05:11Z
  Docker Pull Spec:	docker-registry.default.svc:5000/default/python
  Image Lookup:		local=false
  Unique Images:		1
  Tags:			1
  
  3.5
    tagged from centos/python-35-centos7
  
    * centos/python-35-centos7@sha256:49c18358df82f4577386404991c51a9559f243e0b1bdc366df25
        About a minute ago

• Get all the information available about particular image stream tag:

  $ oc describe istag/<image-stream>:<tag-name>

  For example:

  $ oc describe istag/python:latest

  Example output

  Image Name:	sha256:49c18358df82f4577386404991c51a9559f243e0b1bdc366df25
  Docker Image:	centos/python-35-centos7@sha256:49c18358df82f4577386404991c51a9559f243e0b1bdc366df25
  Name:		sha256:49c18358df82f4577386404991c51a9559f243e0b1bdc366df25
  Created:	2 minutes ago
  Image Size:	251.2 MB (first layer 2.898 MB, last binary layer 72.26 MB)
  Image Created:	2 weeks ago
  Author:		<none>
  Arch:		amd64
  Entrypoint:	container-entrypoint
  Command:	/bin/sh -c $STI_SCRIPTS_PATH/usage
  Working Dir:	/opt/app-root/src
  User:		1001
  Exposes Ports:	8080/tcp
  Docker Labels:	build-date=20170801

Procedure

• Add a tag that points to one of the existing tags by using the `oc tag`command:

  $ oc tag <image-name:tag1> <image-name:tag2>

  For example:

  $ oc tag python:3.5 python:latest

  Example output

  Tag python:latest set to python@sha256:49c18358df82f4577386404991c51a9559f243e0b1bdc366df25.

• Confirm the image stream has two tags, one, 3.5, pointing at the external container image and another tag, latest, pointing to the same image because it was created based on the first tag.

  $ oc describe is/python

  Example output

  Name:			python
  Namespace:		default
  Created:		5 minutes ago
  Labels:			<none>
  Annotations:		openshift.io/image.dockerRepositoryCheck=2017-10-02T17:05:11Z
  Docker Pull Spec:	docker-registry.default.svc:5000/default/python
  Image Lookup:		local=false
  Unique Images:		1
  Tags:			2
  
  latest
    tagged from python@sha256:49c18358df82f4577386404991c51a9559f243e0b1bdc366df25
  
    * centos/python-35-centos7@sha256:49c18358df82f4577386404991c51a9559f243e0b1bdc366df25
        About a minute ago
  
  3.5
    tagged from centos/python-35-centos7
  
    * centos/python-35-centos7@sha256:49c18358df82f4577386404991c51a9559f243e0b1bdc366df25
        5 minutes ago

Procedure

• Add tags pointing to internal or external images, by using the oc tag command for all tag-related operations:

  $ oc tag <repository/image> <image-name:tag>

  For example, this command maps the docker.io/python:3.6.0 image to the 3.6 tag in the python image stream.

  $ oc tag docker.io/python:3.6.0 python:3.6

  Example output

  Tag python:3.6 set to docker.io/python:3.6.0.

  If the external image is secured, you must create a secret with credentials for accessing that registry.

Procedure

• Update a tag:

  $ oc tag <image-name:tag> <image-name:latest>

  For example, the following updates the latest tag to reflect the 3.6 tag in an image stream:

  $ oc tag python:3.6 python:latest

  Example output

  Tag python:latest set to python@sha256:438208801c4806548460b27bd1fbcb7bb188273d13871ab43f.

Procedure

• Remove old tags from an image stream:

  $ oc tag -d <image-name:tag>

  For example:

  $ oc tag -d python:3.5

  Example output

  Deleted tag default/python:3.5.