podman diff accept two images or containers

First, make podman diff accept optionally a second argument. This allows
the user to specify a second image/container to compare the first with.
If it is not set the parent layer will be used as before.

Second, podman container diff should only use containers and podman
image diff should only use images. Previously, podman container diff
would use the image when both an image and container with this name
exists.

To make this work two new parameters have been added to the api. If they
are not used the previous behaviour is used. The same applies to the
bindings.

Fixes #10649

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

1 files changed, 54 insertions, 0 deletions

diff --git a/docs/source/markdown/podman-container-diff.1.md b/docs/source/markdown/podman-container-diff.1.md
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+% podman-container-diff(1)
+
+## NAME
+podman\-container\-diff - Inspect changes on a container's filesystem
+
+## SYNOPSIS
+**podman container diff** [*options*] *container* [*container*]
+
+## DESCRIPTION
+Displays changes on a container's filesystem. The container will be compared to its parent layer or the second argument when given.
+
+The output is prefixed with the following symbols:
+
+| Symbol | Description |
+|--------|-------------|
+| A | A file or directory was added.   |
+| D | A file or directory was deleted. |
+| C | A file or directory was changed. |
+
+## OPTIONS
+
+#### **--format**
+
+Alter the output into a different format. The only valid format for **podman container diff** is `json`.
+
+#### **--latest**, **-l**
+
+Instead of providing the container name or ID, use the last created container. If you use methods other than Podman
+to run containers such as CRI-O, the last started container could be from either of those methods. (This option is not available with the remote Podman client)
+
+## EXAMPLE
+
+```
+# podman container diff container1
+C /usr
+C /usr/local
+C /usr/local/bin
+A /usr/local/bin/docker-entrypoint.sh
+```
+
+```
+$ podman container diff --format json container1 container2
+{
+     "added": [
+          "/test"
+     ]
+}
+```
+
+## SEE ALSO
+**[podman(1)](podman.1.md)**, **[podman-container(1)](podman-container.1.md)**
+
+## HISTORY
+July 2021, Originally compiled by Paul Holzinger <pholzing@redhat.com>