Merge trunk + wsgirouter.

nova/wsgi.py

@@ -22,6 +22,7 @@ Utility methods for working with WSGI servers
 """
 
 import json
+import os
 import sys
 from xml.dom import minidom
 
@@ -34,9 +35,15 @@ import webob
 import webob.dec
 import webob.exc
 
+from paste import deploy
+
+from nova import flags
 from nova import log as logging
 
 
+FLAGS = flags.FLAGS
+
+
 class WritableLogger(object):
     """A thin wrapper that responds to `write` and logs."""
 
@@ -435,3 +442,60 @@ class Serializer(object):
             node = doc.createTextNode(str(data))
             result.appendChild(node)
         return result
+
+def paste_config_file(basename):
+    """Find the best location in the system for a paste config file.
+   
+    Search Order
+    ------------
+
+    The search for a paste config file honors `FLAGS.state_path`, which in a
+    version checked out from bzr will be the `nova` directory in the top level
+    of the checkout, and in an installation for a package for your distribution
+    will likely point to someplace like /etc/nova.
+
+    This method tries to load places likely to be used in development or
+    experimentation before falling back to the system-wide configuration
+    in `/etc/nova/`.
+
+    * Current working directory
+    * the `etc` directory under state_path, because when working on a checkout
+      from bzr this will point to the default
+    * top level of FLAGS.state_path, for distributions
+    * /etc/nova, which may not be diffrerent from state_path on your distro
+
+    """
+
+    configfiles = [basename,
+                   os.path.join(FLAGS.state_path, 'etc', basename),
+                   os.path.join(FLAGS.state_path, basename),
+                   '/etc/nova/%s' % basename]
+    for configfile in configfiles:
+        if os.path.exists(configfile):
+            return configfile
+
+def load_paste_configuration(filename, appname):
+    """Returns a paste configuration dict, or None."""
+    filename = os.path.abspath(filename)
+    config = None
+    try:
+        config = deploy.appconfig("config:%s" % filename, name=appname)
+    except LookupError:
+        pass
+    return config
+
+def load_paste_app(filename, appname):
+    """Builds a wsgi app from a paste config, None if app not configured."""
+    filename = os.path.abspath(filename)
+    app = None
+    try:
+        app = deploy.loadapp("config:%s" % filename, name=appname)
+    except LookupError:
+        pass
+    return app
+
+def paste_config_to_flags(config, mixins):
+    for k,v in mixins.iteritems():
+        value = config.get(k, v)
+        converted_value = FLAGS[k].parser.Parse(value)
+        setattr(FLAGS, k, converted_value)