How to: `REGISTRY` COMMAND OPTIONS
For the operations that require authentication you can reuse the registry credentials from Docker (do `docker login` first and then use the `--use-docker-credentials` flag with the `registry` command) or you can specify the auth info using the `--account` and `--secret` flags).

Current sub-commands: `pull`, `push`, `image-index-create`, `server`.

There's also a placeholder for `copy`, but it doesn't do anything yet. Great opportunity to contribute ;-)

Shared Command Level Flags:

- `--use-docker-credentials` - Use the registry credentials from the default Docker config file.
- `--account` - Registry credentials account.
- `--secret` - Registry credentials secret.

#### `PULL` SUBCOMMAND OPTIONS

USAGE: `slim [GLOBAL FLAGS] registry [SHARED FLAGS] pull [FLAGS] [IMAGE]`

Flags:

- `--target value` - Target container image (name or ID) [$DSLIM_TARGET]
- `--save-to-docker`- Save pulled image to docker (default: true) [$DSLIM_REG_PULL_SAVE_TO_DOCKER]

#### `PUSH` SUBCOMMAND OPTIONS

USAGE: `slim [GLOBAL FLAGS] registry [SHARED FLAGS] push [FLAGS] [IMAGE]`

Flags:

- `--docker` -- Push local docker image.
- `--tar` -- Push image from a local tar file.
- `--as` -- Tag the selected image with the specified name before pushing.

Note that `slim registry push LOCAL_DOCKER_IMAGE_NAME` is a shortcut for `slim registry push --docker LOCAL_DOCKER_IMAGE_NAME`.

Normally you have to explicitly tag the target image to have a name that's appropriate for the destination registry. The `--as` flag is a convenient way to tag the image while you are pushing it. Here's an example pushing a local Docker `nginx` image to a local registry: `slim registry push --docker nginx --as localhost:5000/nginx`

You can create a local registry using the `server` subcommand. See the `server` sub-command section below for more details.

#### `COPY` SUBCOMMAND OPTIONS

USAGE: `slim registry copy [SRC_IMAGE] [DST_IMAGE]`

NOTE: Just a placeholder for now (TBD)

#### `IMAGE-INDEX-CREATE` SUBCOMMAND OPTIONS

USAGE: `slim registry image-index-create --image-index-name [MULTI-ARCH_IMAGE_TAG] --image-name [IMAGE_ONE] --image-name [IMAGE_TWO]`

Flags: 

- `--image-index-name` - Image index name to use.
- `--image-name` - Target image name to include in image index.
- `--as-manifest-list` - Create image index with the manifest list media type instead of the default OCI image index type.
- `--dump-raw-manifest` - Dump raw manifest for the created image index.
- `--insecure-refs` - Allow the referenced images from insecure registry connections.

#### `SERVER` SUBCOMMAND OPTIONS

Starts a server which implements the [OCI API spec](https://github.com/opencontainers/distribution-spec/blob/v1.0.1/spec.md) on port 5000 by default.

USAGE: `slim [GLOBAL FLAGS] registry server [FLAGS]`

Flags:

- `--address` - Registry server address to listen on (default: `0.0.0.0`)
- `--port` - Registry server port (default: 5000)
- `--https` - Use HTTPS.
- `--cert-path` - Cert path for use with HTTPS (for use when not using autocert).
- `--key-path` - Key path for use with HTTPS (for use when not using autocert).
- `--domain` - Domain to use for registry server (to get certs). Only works if the registry is internet accessible (see `autocert` Go docs for more details).
- `--referrers-api` - Enables the [referrers API endpoint](https://github.com/opencontainers/distribution-spec/blob/v1.1.0-rc3/spec.md#enabling-the-referrers-api) (OCI 1.1+). Enabled by default (set to `false` to disable).