Fix issues with configuration/parameters loading

- Change default server directory from plinth/ to /plinth as the program
  expects.

- First load the values from configuration file and then override them
  with command line parameters.

- Show default values on the command line help.

- Use configuration file values as default values to command line
  parameters.

- Log the value of script prefix (server_dir) for easy debugging.

- Make sure the server_dir is properly loaded from configuration files.

data/etc/plinth/plinth.config

@@ -9,7 +9,7 @@ config_dir = /etc/plinth
 data_dir = /var/lib/plinth
 log_dir = /var/log/plinth
 pid_dir = /var/run
-server_dir = plinth/
+server_dir = /plinth
 actions_dir = /usr/share/plinth/actions
 doc_dir = /usr/share/doc/plinth
 

plinth/__main__.py

@@ -40,19 +40,20 @@ LOGGER = logging.getLogger(__name__)
 def parse_arguments():
     """Parse command line arguments"""
     parser = argparse.ArgumentParser(
-        description='Plinth web interface for FreedomBox')
+        description='Plinth web interface for FreedomBox',
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter)
     parser.add_argument(
-        '--pidfile', default='plinth.pid',
+        '--pidfile', default=cfg.pidfile,
         help='specify a file in which the server may write its pid')
     # TODO: server_dir is actually a url prefix; use a better variable name
     parser.add_argument(
-        '--server_dir', default='/',
+        '--server_dir', default=cfg.server_dir,
         help='web server path under which to serve')
     parser.add_argument(
-        '--debug', action='store_true', default=False,
+        '--debug', action='store_true', default=cfg.debug,
         help='enable debugging and run server *insecurely*')
     parser.add_argument(
-        '--no-daemon', action='store_true', default=False,
+        '--no-daemon', action='store_true', default=cfg.no_daemon,
         help='do not start as a daemon')
 
     args = parser.parse_args()
@@ -239,10 +240,10 @@ def configure_django():
 
 def main():
     """Intialize and start the application"""
-    parse_arguments()
-
     cfg.read()
 
+    parse_arguments()
+
     setup_logging()
 
     service.init()
@@ -250,6 +251,7 @@ def main():
     configure_django()
 
     LOGGER.info('Configuration loaded from file - %s', cfg.CONFIG_FILE)
+    LOGGER.info('Script prefix - %s', cfg.server_dir)
 
     module_loader.load_modules()
 

plinth/cfg.py

@@ -78,6 +78,7 @@ def read():
                     ('Path', 'status_log_file'),
                     ('Path', 'access_log_file'),
                     ('Path', 'pidfile'),
+                    ('Path', 'server_dir'),
                     ('Network', 'host'),
                     ('Network', 'port'),
                     ('Network', 'secure_proxy_ssl_header'),