Merge pull request #6053 from thaJeztah/import_docs

docs: import: assorted fixes and touch-ups

Author: thaJeztah

docs/reference/commandline/image_import.md

@@ -9,11 +9,11 @@ Import the contents from a tarball to create a filesystem image
 
 ### Options
 
-| Name              | Type     | Default | Description                                       |
-|:------------------|:---------|:--------|:--------------------------------------------------|
-| `-c`, `--change`  | `list`   |         | Apply Dockerfile instruction to the created image |
-| `-m`, `--message` | `string` |         | Set commit message for imported image             |
-| `--platform`      | `string` |         | Set platform if server is multi-platform capable  |
+| Name                                      | Type     | Default | Description                                       |
+|:------------------------------------------|:---------|:--------|:--------------------------------------------------|
+| [`-c`](#change), [`--change`](#change)    | `list`   |         | Apply Dockerfile instruction to the created image |
+| [`-m`](#message), [`--message`](#message) | `string` |         | Set commit message for imported image             |
+| [`--platform`](#platform)                 | `string` |         | Set platform if server is multi-platform capable  |
 
 
 <!---MARKER_GEN_END-->
@@ -28,10 +28,6 @@ specify an archive, Docker untars it in the container relative to the `/`
 the host. To import from a remote location, specify a `URI` that begins with the
 `http://` or `https://` protocol.
 
-The `--change` option applies `Dockerfile` instructions to the image that is
-created. Supported `Dockerfile` instructions:
-`CMD`|`ENTRYPOINT`|`ENV`|`EXPOSE`|`ONBUILD`|`USER`|`VOLUME`|`WORKDIR`
-
 ## Examples
 
 ### Import from a remote location
@@ -50,12 +46,6 @@ Import to docker via pipe and `STDIN`.
 $ cat exampleimage.tgz | docker import - exampleimagelocal:new
 ```
 
-Import with a commit message.
-
-```console
-$ cat exampleimage.tgz | docker import --message "New image imported from tarball" - exampleimagelocal:new
-```
-
 Import to docker from a local archive.
 
 ```console
@@ -68,17 +58,71 @@ $ docker import /path/to/exampleimage.tgz
 $ sudo tar -c . | docker import - exampleimagedir
 ```
 
-### Import from a local directory with new configurations
-
-```console
-$ sudo tar -c . | docker import --change "ENV DEBUG=true" - exampleimagedir
-```
-
 Note the `sudo` in this example – you must preserve
 the ownership of the files (especially root ownership) during the
 archiving with tar. If you are not root (or the sudo command) when you
 tar, then the ownerships might not get preserved.
 
+### <a name="change"></a> Import with new configurations (-c, --change)
+
+The `--change` option applies `Dockerfile` instructions to the image that is
+created. Not all `Dockerfile` instructions are supported; the list of instructions
+is limited to metadata (configuration) changes. The following `Dockerfile`
+instructions are supported:
+
+- [`CMD`](https://docs.docker.com/reference/dockerfile/#cmd)
+- [`ENTRYPOINT`](https://docs.docker.com/reference/dockerfile/#entrypoint)
+- [`ENV`](https://docs.docker.com/reference/dockerfile/#env)
+- [`EXPOSE`](https://docs.docker.com/reference/dockerfile/#expose)
+- [`HEALTHCHECK`](https://docs.docker.com/reference/dockerfile/#healthcheck)
+- [`LABEL`](https://docs.docker.com/reference/dockerfile/#label)
+- [`ONBUILD`](https://docs.docker.com/reference/dockerfile/#onbuild)
+- [`STOPSIGNAL`](https://docs.docker.com/reference/dockerfile/#stopsignal)
+- [`USER`](https://docs.docker.com/reference/dockerfile/#user)
+- [`VOLUME`](https://docs.docker.com/reference/dockerfile/#volume)
+- [`WORKDIR`](https://docs.docker.com/reference/dockerfile/#workdir)
+
+The following example imports an image from a TAR-file containing a root-filesystem,
+and sets the `DEBUG` environment-variable in the resulting image:
+
+```console
+$ docker import --change "ENV DEBUG=true" ./rootfs.tgz exampleimagedir
+```
+
+The `--change` option can be set multiple times to apply multiple `Dockerfile`
+instructions. The example below sets the `LABEL1` and `LABEL2` labels on
+the imported image, in addition to the `DEBUG` environment variable from
+the previous example:
+
+```console
+$ docker import \
+    --change "ENV DEBUG=true" \
+    --change "LABEL LABEL1=hello" \
+    --change "LABEL LABEL2=world" \
+    ./rootfs.tgz exampleimagedir
+```
+
+### <a name="message"></a> Import with a commit message (-m, --message)
+
+The `--message`  (or `-m`) option allows you to set a custom comment in
+the image's metadata. The following example imports an image from a local
+archive and sets a custom message.
+
+```console
+$ docker import --message "New image imported from tarball" ./rootfs.tgz exampleimagelocal:new
+sha256:25e54c0df7dc49da9093d50541e0ed4508a6b78705057f1a9bebf1d564e2cb00
+```
+
+After importing, the message is set in the "Comment" field of the image's
+configuration, which is shown when viewing the image's history:
+
+```console
+$ docker image history exampleimagelocal:new
+
+IMAGE          CREATED         CREATED BY   SIZE      COMMENT
+25e54c0df7dc   2 minutes ago                53.6MB    New image imported from tarball
+```
+
 ### When the daemon supports multiple operating systems
 
 If the daemon supports multiple operating systems, and the image being imported
@@ -89,3 +133,31 @@ daemon.
 ```console
 $ docker import --platform=linux .\linuximage.tar
 ```
+
+### <a name="platform"></a> Set the platform for the imported image (--platform)
+
+The `--platform` option allows you to specify the platform for the imported
+image. By default, the daemon's native platform is used as platform, but
+the `--platform` option allows you to override the default, for example, in
+situations where the imported root filesystem is for a different architecture
+or operating system.
+
+The platform option takes the `os[/arch[/variant]]` format; for example,
+`linux/amd64` or `linux/arm64/v8`. Architecture and variant are optional,
+and default to the daemon's native architecture if omitted.
+
+The following example imports an image from a root-filesystem in `rootfs.tgz`,
+and sets the image's platform to `linux/amd64`;
+
+```console
+$ docker image import --platform=linux/amd64  ./rootfs.tgz imported:latest
+sha256:44a8b44157dad5edcff85f0c93a3e455f3b20a046d025af4ec50ed990d7ebc09
+```
+
+After importing the image, the image's platform is set in the image's
+configuration;
+
+```console
+$ docker image inspect --format '{{.Os}}/{{.Architecture}}' imported:latest
+linux/amd64
+```