cephadm: Add '--mount' option to mount host file or directory

Fixes: https://tracker.ceph.com/issues/45284

Signed-off-by: Ricardo Marques <rimarques@suse.com>

doc/cephadm/install.rst

@@ -110,7 +110,7 @@ Enable Ceph CLI
 ===============
 
 Cephadm does not require any Ceph packages to be installed on the
-host.  However, we recommend enabling easy access to the the ``ceph``
+host.  However, we recommend enabling easy access to the ``ceph``
 command.  There are several ways to do this:
 
 * The ``cephadm shell`` command launches a bash shell in a container
@@ -119,7 +119,9 @@ command.  There are several ways to do this:
   host, they are passed into the container environment so that the
   shell is fully functional. Note that when executed on a MON host,
   ``cephadm shell`` will infer the ``config`` from the MON container
-  instead of using the default configuration::
+  instead of using the default configuration. If ``--mount <path>``
+  is given, then the host ``<path>`` (file or directory) will appear
+  under ``/mnt`` inside the container::
 
     # cephadm shell
 

src/cephadm/cephadm

@@ -2778,6 +2778,12 @@ def command_shell():
         mounts[pathify(args.config)] = '/etc/ceph/ceph.conf:z'
     if args.keyring:
         mounts[pathify(args.keyring)] = '/etc/ceph/ceph.keyring:z'
+    if args.mount:
+        mount = pathify(args.mount)
+        filename = ''
+        if os.path.isfile(mount):
+            _, filename = os.path.split(mount)
+        mounts[mount] = '/mnt/{}:z'.format(filename)
     if args.command:
         command = args.command
     else:
@@ -4301,6 +4307,9 @@ def _get_parser():
     parser_shell.add_argument(
         '--keyring', '-k',
         help='ceph.keyring to pass through to the container')
+    parser_shell.add_argument(
+        '--mount', '-m',
+        help='file or directory path that will be mounted in container /mnt')
     parser_shell.add_argument(
         '--env', '-e',
         action='append',