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feat: Update image name documentation

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Sergey Shevchenko 2024-04-06 15:26:50 +03:00
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content/en/docs/concepts/containers/images.md
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@ -33,17 +33,35 @@ Container images are usually given a name such as `pause`, `example/mycontainer`
Images can also include a registry hostname; for example: `fictional.registry.example/imagename`,
and possibly a port number as well; for example: `fictional.registry.example:10443/imagename`.
If you don't specify a registry hostname, Kubernetes assumes that you mean the Docker public registry.
If you don't specify a registry hostname, Kubernetes assumes that you mean the [Docker public registry](https://hub.docker.com/).
You can change this behaviour by setting default image registry in [container runtime](/docs/setup/production-environment/container-runtimes/) configuration.
After the image name part you can add a _tag_ (in the same way you would when using with commands
like `docker` or `podman`). Tags let you identify different versions of the same series of images.
After the image name part you can add a _tag_ or _digest_ (in the same way you would when using with commands
like `docker` or `podman`). Tags let you identify different versions of the same series of images.
Digests are a unique identifier for a specific version of an image. Digests are hashes of the image's content,
and are immutable. Tags can be moved to point to different images, but digests are fixed.
Image tags consist of lowercase and uppercase letters, digits, underscores (`_`),
periods (`.`), and dashes (`-`).
There are additional rules about where you can place the separator
characters (`_`, `-`, and `.`) inside an image tag.
periods (`.`), and dashes (`-`). It can be up to 128 characters long. And must follow the
next regex pattern: `[a-zA-Z0-9_][a-zA-Z0-9._-]{0,127}`
You can read more about and find validation regex in the
[OCI Distribution Specification](https://github.com/opencontainers/distribution-spec/blob/v1.1.0/spec.md#workflow-categories).
If you don't specify a tag, Kubernetes assumes you mean the tag `latest`.
Image digests consists of a hash algorithm (such as `sha256`) and a hash value. For example:
`sha256:1ff6c18fbef2045af6b9c16bf034cc421a29027b800e4f9b68ae9b1cb3e9ae07`
You can find more information about digests format in the
[OCI Image Specification](https://github.com/opencontainers/image-spec/blob/v1.1.0/descriptor.md#digests).
Some image name examples that Kubernetes can use are:
- `busybox` - Image name only, no tag or digest. Kubernetes will use Docker public registry and latest tag. (Same as `docker.io/library/busybox:latest`)
- `busybox:1.32.0` - Image name with tag. Kubernetes will use Docker public registry. (Same as `docker.io/library/busybox:1.32.0`)
- `registry.k8s.io/pause:latest` - Image name with a custom registry and latest tag.
- `registry.k8s.io/pause:3.5` - Image name with a custom registry and non-latest tag.
- `registry.k8s.io/pause@sha256:1ff6c18fbef2045af6b9c16bf034cc421a29027b800e4f9b68ae9b1cb3e9ae07` - Image name with digest.
- `registry.k8s.io/pause:3.5@sha256:1ff6c18fbef2045af6b9c16bf034cc421a29027b800e4f9b68ae9b1cb3e9ae07` - Image name with tag and digest. Only digest will be used for pulling.
## Updating images
When you first create a {{< glossary_tooltip text="Deployment" term_id="deployment" >}},