add --version argument

it prints the version

backupmgr/application.py

@@ -174,6 +174,10 @@ class Application(object):
                 archives_to_prune = engine.prunable_archives(archives)
                 engine.prune_archives(archives_to_prune)
 
+    def print_version(self):
+        from . import _metadata
+        print(f"backupmgr {_metadata.__version__}")
+
     def unknown_verb(self):
         raise Exception("Unknown verb")
 
@@ -184,7 +188,8 @@ class Application(object):
             "list-configured-backups": self.list_configured_backups,
             "list-backends": self.list_backends,
             "restore": self.restore_backup,
-            "prune": self.prune_archives
+            "prune": self.prune_archives,
+            "version": self.print_version,
         }
         try:
             self.bootstrap()

backupmgr/configuration.py

@@ -140,6 +140,8 @@ class Config(object):
         parser = argparse.ArgumentParser(prog=self.prog)
         parser.add_argument("-q", "--quiet", action="store_true",
                             help="Be quiet on logging to stdout/stderr")
+        parser.add_argument("--version", action="store_const", dest="verb",
+                        const="version")
         parser.set_defaults(verb=None)
         subparsers = parser.add_subparsers()