If the help subcommand is given, print the help output.

This isn't a real subcommand like the others.  The option processing
just intercepts it and prints the output.  Given that we're subcommand
based, it makes sense to support this in addition to --help.

(cherry picked from commit 3743d6d208)
(cherry picked from commit 3c6478e179)

src/bin/composer-cli

@@ -47,7 +47,8 @@ def setup_logging(logfile):
 
 if __name__ == '__main__':
     # parse the arguments
-    opts = composer_cli_parser().parse_args()
+    arg_parser = composer_cli_parser()
+    opts = arg_parser.parse_args()
 
     if opts.showver:
         print(VERSION)
@@ -59,6 +60,16 @@ if __name__ == '__main__':
     setup_logging(opts.logfile)
     log.debug("opts=%s", opts)
 
+    if len(opts.args) == 0:
+        log.error("Missing command")
+        sys.exit(1)
+    elif opts.args[0] == "help":
+        arg_parser.print_help()
+        sys.exit(0)
+    elif len(opts.args) == 1:
+        log.error("Missing %s sub-command", opts.args[0])
+        sys.exit(1)
+
     errors = []
 
     # Check to see if the socket exists and can be accessed

src/composer/cli/__init__.py

@@ -40,15 +40,12 @@ def main(opts):
     :param opts: Cmdline arguments
     :type opts: argparse.Namespace
     """
-    if len(opts.args) == 0:
-        log.error("Missing command")
-        return 1
-    elif opts.args[0] not in command_map:
+
+    # Making sure opts.args is not empty (thus, has a command and subcommand)
+    # is already handled in src/bin/composer-cli.
+    if opts.args[0] not in command_map:
         log.error("Unknown command %s", opts.args[0])
         return 1
-    if len(opts.args) == 1:
-        log.error("Missing %s sub-command", opts.args[0])
-        return 1
     else:
         try:
             return command_map[opts.args[0]](opts)