Separate wsgi init from web-front-end activation

Separate the request processor initialization steps
    Load common settings from conf
    Set the logger
    Load the request processor
from the web front end server application step

On branch bp/wsgi-application-interface-7
   modified:   swift/common/wsgi.py

Implements Blueprint:   wsgi-application-interface

Change-Id: I25fabad8846cd644e4bf1e1bd9c2e568512e12e5

swift/common/wsgi.py

@@ -104,41 +104,23 @@ def get_socket(conf, default_port=8080):
 # TODO: pull pieces of this out to test
 def run_wsgi(conf_file, app_section, *args, **kwargs):
     """
-    Loads common settings from conf, then instantiates app and runs
-    the server using the specified number of workers.
+    Runs the server using the specified number of workers.
 
     :param conf_file: Path to paste.deploy style configuration file
     :param app_section: App name from conf file to load config from
     """
-
+    # Load configuration, Set logger and Load request processor
     try:
-        conf = appconfig('config:%s' % conf_file, name=app_section)
-    except Exception, e:
-        print "Error trying to load config %s: %s" % (conf_file, e)
+        (app, conf, logger, log_name) = \
+            init_request_processor(conf_file, app_section, *args, **kwargs)
+    except ConfigFileError, e:
+        print e
         return
-    validate_configuration()
-
-    # pre-configure logger
-    log_name = conf.get('log_name', app_section)
-    if 'logger' in kwargs:
-        logger = kwargs.pop('logger')
-    else:
-        logger = get_logger(conf, log_name,
-                            log_to_console=kwargs.pop('verbose', False),
-                            log_route='wsgi')
-
-    # disable fallocate if desired
-    if config_true_value(conf.get('disable_fallocate', 'no')):
-        disable_fallocate()
 
     # bind to address and port
     sock = get_socket(conf, default_port=kwargs.get('default_port', 8080))
     # remaining tasks should not require elevated privileges
     drop_privileges(conf.get('user', 'swift'))
-
-    # Ensure the application can be loaded before proceeding.
-    loadapp('config:%s' % conf_file, global_conf={'log_name': log_name})
-
     # redirect errors to logger and close stdio
     capture_stdio(logger)
 
@@ -152,7 +134,6 @@ def run_wsgi(conf_file, app_section, *args, **kwargs):
         wsgi.WRITE_TIMEOUT = int(conf.get('client_timeout') or 60)
         eventlet.hubs.use_hub('poll')
         eventlet.patcher.monkey_patch(all=False, socket=True)
-        monkey_patch_mimetools()
         app = loadapp('config:%s' % conf_file,
                       global_conf={'log_name': log_name})
         pool = GreenPool(size=1024)
@@ -214,6 +195,47 @@ def run_wsgi(conf_file, app_section, *args, **kwargs):
     logger.notice('Exited')
 
 
+class ConfigFileError(Exception):
+    pass
+
+
+def init_request_processor(conf_file, app_section, *args, **kwargs):
+    """
+    Loads common settings from conf
+    Sets the logger
+    Loads the request processor
+
+    :param conf_file: Path to paste.deploy style configuration file
+    :param app_section: App name from conf file to load config from
+    :returns the loaded application entry point
+    :raises ConfigFileError: Exception is raised for config file error
+    """
+    try:
+        conf = appconfig('config:%s' % conf_file, name=app_section)
+    except Exception, e:
+        raise ConfigFileError("Error trying to load config %s: %s" %
+                              (conf_file, e))
+
+    validate_configuration()
+
+    # pre-configure logger
+    log_name = conf.get('log_name', app_section)
+    if 'logger' in kwargs:
+        logger = kwargs.pop('logger')
+    else:
+        logger = get_logger(conf, log_name,
+                            log_to_console=kwargs.pop('verbose', False),
+                            log_route='wsgi')
+
+    # disable fallocate if desired
+    if config_true_value(conf.get('disable_fallocate', 'no')):
+        disable_fallocate()
+
+    monkey_patch_mimetools()
+    app = loadapp('config:%s' % conf_file, global_conf={'log_name': log_name})
+    return (app, conf, logger, log_name)
+
+
 class WSGIContext(object):
     """
     This class provides a means to provide context (scope) for a middleware