Allows passing of config file via --config-file option.

Maintains backwards compatibility with the old style invocation,
by adding a config_shim method. Logs a warning if the old style
invocation is used.

Change-Id: I11666a2fff0e9bdc6b26cb46505dcb03fa06fa50
Closes-Bug: #1411194

CONTRIBUTING.rst

@@ -55,7 +55,7 @@ Github::
 
 Run the service with::
 
-    .tox/py27/bin/ironic-discoverd example.conf
+    .tox/py27/bin/ironic-discoverd --config-file example.conf
 
 Of course you may have to modify ``example.conf`` to match your OpenStack
 environment.

README.rst

@@ -133,7 +133,7 @@ unit, so you can::
 
 Otherwise run as ``root``::
 
-    ironic-discoverd /etc/ironic-discoverd/discoverd.conf
+    ironic-discoverd --config-file /etc/ironic-discoverd/discoverd.conf
 
 *ironic-discoverd* has a simple client library bundled within it.
 It provides function ``ironic_discoverd.client.discover``, accepting list

ironic_discoverd/main.py

@@ -14,6 +14,7 @@
 import eventlet
 eventlet.monkey_patch(thread=False)
 
+import argparse
 import functools
 import json
 import logging
@@ -147,11 +148,22 @@ def check_ironic_available():
         eventlet.greenthread.sleep(retry_period)
 
 
-def main():
-    if len(sys.argv) < 2:
-        sys.exit("Usage: %s config-file" % sys.argv[0])
+def config_shim(args):
+    """Make new argument parsing method backwards compatible."""
+    if len(args) == 2 and args[1][0] != '-':
+        return ['--config-file', args[1]]
 
-    conf.read(sys.argv[1])
+
+def main():
+    old_args = config_shim(sys.argv)
+    parser = argparse.ArgumentParser(description='''Hardware introspection
+                                                 service for OpenStack Ironic.
+                                                 ''')
+    parser.add_argument('--config-file', dest='config', required=True)
+    # if parse_args is passed None it uses sys.argv instead.
+    args = parser.parse_args(old_args)
+
+    conf.read(args.config)
     debug = conf.getboolean('discoverd', 'debug')
 
     logging.basicConfig(level=logging.DEBUG if debug else logging.INFO)
@@ -161,6 +173,10 @@ def main():
     logging.getLogger('ironicclient.common.http').setLevel(
         logging.INFO if debug else logging.ERROR)
 
+    if old_args:
+        LOG.warning('"ironic-discoverd <config-file>" syntax is deprecated use'
+                    ' "ironic-discoverd --config-file <config-file>" instead')
+
     if not conf.getboolean('discoverd', 'authenticate'):
         LOG.warning('Starting unauthenticated, please check configuration')
 

ironic_discoverd/test/test_main.py

@@ -167,3 +167,15 @@ class TestPlugins(unittest.TestCase):
     def test_manager_is_cached(self):
         self.assertIs(plugins_base.processing_hooks_manager(),
                       plugins_base.processing_hooks_manager())
+
+
+class TestConfigShim(unittest.TestCase):
+    def test_old_style_invocation(self):
+        self.assertEqual(main.config_shim(
+                         ['ironic-discoverd', '/etc/conf']),
+                         ['--config-file', '/etc/conf'])
+
+    def test_new_style_returns_None(self):
+        self.assertEqual(main.config_shim(
+                         ['ironic-discoverd', '--config-file', '/etc/conf']),
+                         None)