cephadm: improve cephadm pull usage message

Generally, it's uncommon for users to run this
directly, but in case they need to for debugging
purposes, we should include how to pass the
image to be pulled in the usage message.

Additionally, include that this is only to be used
for pulling ceph images in the help message, as
that isn't necessarily clear. Pulling anything
else will result in a traceback as it tries
to run `ceph --version` inside the container.

Signed-off-by: Adam King <adking@redhat.com>

diff --git a/src/cephadm/cephadm.py b/src/cephadm/cephadm.py
index 21523cd09ea0fb867cb0849f472bd9c30af2cf68..b13ca406f015df74f31a43dd5794f64ec10dfca0 100755 (executable)
--- a/src/cephadm/cephadm.py
+++ b/src/cephadm/cephadm.py
@@ -4857,7 +4857,9 @@ def _get_parser():
     )
 
     parser_pull = subparsers.add_parser(
-        'pull', help='pull the default container image')
+        'pull',
+        help='pull a ceph container image (will pull the default image if --image not provided)',
+        usage='cephadm pull (for default image) | cephadm --image <image-name> pull (for custom ceph image)')
     parser_pull.set_defaults(func=command_pull)
     parser_pull.add_argument(
         '--insecure',