Chapter 4. Working with container images

Prerequisites

• The container-tools module is installed.

Procedure

• Pull the container image:

  • Pull the fedora image:

    $ podman pull fedora
    Resolved "fedora" as an alias (/etc/containers/registries.conf.d/000-shortnames.conf)
    Trying to pull registry.fedoraproject.org/fedora:latest…
    ...
    Storing signatures
    ...

    Alias is found and the registry.fedoraproject.org/fedora image is securely pulled. The unqualified-search-registries list is not used to resolve fedora image name.

  • Pull the nginx image:

    $ podman pull nginx
    ? Please select an image:
    registry.access.redhat.com/nginx:latest
    registry.redhat.io/nginx:latest
      ▸ docker.io/library/nginx:latest
    ✔ docker.io/library/nginx:latest
    Trying to pull docker.io/library/nginx:latest…
    ...
    Storing signatures
    ...

    If no matching alias is found, you are prompted to choose one of the unqualified-search-registries list. If the selected image is pulled successfully, a new short-name alias is recorded locally, otherwise an error occurs.

Verification

• List all images pulled to your local system:

  $ podman images
  REPOSITORY                                   TAG     IMAGE ID      CREATED        SIZE
  registry.fedoraproject.org/fedora            latest  28317703decd  12 days ago    184 MB
  docker.io/library/nginx                      latest  08b152afcfae  13 days ago    137 MB

Prerequisites

• The container-tools module is installed.
• A pulled image is available on the local system.

Procedure

• List all images in the local storage:

  $ podman images
  REPOSITORY                           TAG     IMAGE ID      CREATED      SIZE
  registry.access.redhat.com/ubi8/ubi  latest  3269c37eae33  6 weeks ago  208 MB

Prerequisites

• The container-tools module is installed.
• A pulled image is available on the local system.

Procedure

• Inspect the registry.redhat.io/ubi8/ubi image:

  $ podman inspect registry.redhat.io/ubi8/ubi
  …
   "Cmd": [
          "/bin/bash"
      ],
      "Labels": {
          "architecture": "x86_64",
          "build-date": "2020-12-10T01:59:40.343735",
          "com.redhat.build-host": "cpt-1002.osbs.prod.upshift.rdu2.redhat.com",
          "com.redhat.component": "ubi8-container",
          "com.redhat.license_terms": "https://www.redhat.com/...,
      "description": "The Universal Base Image is ...
      }
  ...

  The "Cmd" key specifies a default command to run within a container. You can override this command by specifying a command as an argument to the podman run command. This ubi8/ubi container will execute the bash shell if no other argument is given when you start it with podman run. If an "Entrypoint" key was set, its value would be used instead of the "Cmd" value, and the value of "Cmd" is used as an argument to the Entrypoint command.

Prerequisites

• The container-tools module is installed.

Procedure

• The container-tools module is installed.

• Inspect the registry.redhat.io/ubi8/ubi-init image:

  # skopeo inspect docker://registry.redhat.io/ubi8/ubi-init
  {
      "Name": "registry.redhat.io/ubi8/ubi8-init",
      "Digest": "sha256:c6d1e50ab...",
      "RepoTags": [
          ...
          "latest"
      ],
     "Created": "2020-12-10T07:16:37.250312Z",
      "DockerVersion": "1.13.1",
      "Labels": {
          "architecture": "x86_64",
          "build-date": "2020-12-10T07:16:11.378348",
          "com.redhat.build-host": "cpt-1007.osbs.prod.upshift.rdu2.redhat.com",
          "com.redhat.component": "ubi8-init-container",
          "com.redhat.license_terms": "https://www.redhat.com/en/about/red-hat-end-user-license-agreements#UBI",
          "description": "The Universal Base Image Init is designed to run an init system as PID 1 for running multi-services inside a container
          ...
      }
  }

Prerequisites

• The container-tools module is installed.

Procedure

• Copy the skopeo container image from docker://quay.io to docker://registry.example.com:

  $ skopeo copy docker://quay.io/skopeo/stable:latest docker://registry.example.com/skopeo:latest

Prerequisites

• The container-tools module is installed.

Verification

• Display the content of the /var/lib/images/nginx directory:

  $ ls /var/lib/images/nginx
  08b11a3d692c1a2e15ae840f2c15c18308dcb079aa5320e15d46b62015c0f6f3
  ...
  4fcb23e29ba19bf305d0d4b35412625fea51e82292ec7312f9be724cb6e31ffd  manifest.json
  version

Prerequisites

• The container-tools module is installed.
• A pulled image is available on the local system.

• by ID (3269c37eae33)
• by name (localhost/myubi:latest)
• by name (localhost/myubi:8)

• docker-archive
• oci-archive
• oci-dir (directory with oci manifest type)
• docker-dir (directory with v2s2 manifest type)

Prerequisites

• The container-tools module is installed.
• A pulled image is available on the local system.

Prerequisites

• The container-tools module is installed.
• A pulled image is available on the local system.

Prerequisites

• The container-tools module is installed.