Red Hat Summit3장. Working with container registries
A container image registry is a repository or collection of repositories for storing container images and container-based application artifacts. The /etc/containers/registries.conf file is a system-wide configuration file containing the container image registries that can be used by the various container tools such as Podman, Buildah, and Skopeo.
If the container image given to a container tool is not fully qualified, then the container tool references the registries.conf file. Within the registries.conf file, you can specify aliases for short names, granting administrators full control over where images are pulled from when not fully qualified. For example, the podman pull example.com/example_image command pulls a container image from the example.com registry to your local system as specified in the registries.conf file.
3.1. Container registries
A container registry is a repository or collection of repositories for storing container images and container-based application artifacts. The registries that Red Hat provides are:
- registry.redhat.io (requires authentication)
- registry.access.redhat.com (requires no authentication)
- registry.connect.redhat.com (holds Red Hat Partner Connect program images)
To get container images from a remote registry, such as Red Hat’s own container registry, and add them to your local system, use the podman pull command:
# podman pull <registry>[:<port>]/[<namespace>/]<name>:<tag>
where <registry>[:<port>]/[<namespace>/]<name>:<tag> is the name of the container image.
For example, the registry.redhat.io/ubi10/ubi container image is identified by:
-
Registry server (
registry.redhat.io) -
Namespace (
ubi10) -
Image name (
ubi)
If there are multiple versions of the same image, add a tag to explicitly specify the image name. By default, Podman uses the :latest tag, for example ubi10/ubi:latest.
Some registries also use <namespace> to distinguish between images with the same <name> owned by different users or organizations. For example:
| Namespace | Examples (<namespace>/<name>) |
|---|---|
| organization |
|
| login (user name) |
|
| role |
|
Use fully qualified image names including registry, namespace, image name, and tag. When using short names, there is always an inherent risk of spoofing. Add registries that are trusted, that is, registries that do not allow unknown or anonymous users to create accounts with arbitrary names. For example, a user wants to pull the example container image from example.registry.com registry. If example.registry.com is not first in the search list, an attacker could place a different example image at a registry earlier in the search list. The user would accidentally pull and run the attacker image rather than the intended content.
For details on the transition to registry.redhat.io, see Red Hat Container Registry Authentication. Before you can pull containers from registry.redhat.io, you need to authenticate using your RHEL Subscription credentials.
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