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>
(cherry picked from commit 90b8ba9fc09ace4e4114152b194239061c7acb31)

diff --git a/src/cephadm/cephadm.py b/src/cephadm/cephadm.py
index 5a2e248c62f16dfb80dea370efdcf0555e99b944..dfab33addcbecb13bcd57b0d0defcb9f5dc2ee69 100755 (executable)
--- a/src/cephadm/cephadm.py
+++ b/src/cephadm/cephadm.py
@@ -10187,7 +10187,9 @@ def _get_parser():
     parser_version.set_defaults(func=command_version)
 
     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',