merged to trunk rev572

1 files changed, 120 insertions, 2 deletions

diff --git a/nova/wsgi.py b/nova/wsgi.py
index 00b351253..4f5307d80 100644
--- a/nova/wsgi.py
+++ b/nova/wsgi.py
@@ -21,6 +21,7 @@
 Utility methods for working with WSGI servers
 """
 
+import os
 import sys
 from xml.dom import minidom
 
@@ -33,10 +34,16 @@ import webob
 import webob.dec
 import webob.exc
 
+from paste import deploy
+
+from nova import flags
 from nova import log as logging
 from nova import utils
 
 
+FLAGS = flags.FLAGS
+
+
 class WritableLogger(object):
     """A thin wrapper that responds to `write` and logs."""
 
@@ -76,10 +83,33 @@ class Server(object):
 
 
 class Application(object):
-# TODO(gundlach): I think we should toss this class, now that it has no
-# purpose.
     """Base WSGI application wrapper. Subclasses need to implement __call__."""
 
+    @classmethod
+    def factory(cls, global_config, **local_config):
+        """Used for paste app factories in paste.deploy config fles.
+
+        Any local configuration (that is, values under the [app:APPNAME]
+        section of the paste config) will be passed into the `__init__` method
+        as kwargs.
+
+        A hypothetical configuration would look like:
+
+            [app:wadl]
+            latest_version = 1.3
+            paste.app_factory = nova.api.fancy_api:Wadl.factory
+
+        which would result in a call to the `Wadl` class as
+
+            import nova.api.fancy_api
+            fancy_api.Wadl(latest_version='1.3')
+
+        You could of course re-implement the `factory` method in subclasses,
+        but using the kwarg passing it shouldn't be necessary.
+
+        """
+        return cls(**local_config)
+
     def __call__(self, environ, start_response):
         r"""Subclasses will probably want to implement __call__ like this:
 
@@ -125,6 +155,33 @@ class Middleware(Application):
     behavior.
     """
 
+    @classmethod
+    def factory(cls, global_config, **local_config):
+        """Used for paste app factories in paste.deploy config fles.
+
+        Any local configuration (that is, values under the [filter:APPNAME]
+        section of the paste config) will be passed into the `__init__` method
+        as kwargs.
+
+        A hypothetical configuration would look like:
+
+            [filter:analytics]
+            redis_host = 127.0.0.1
+            paste.filter_factory = nova.api.analytics:Analytics.factory
+
+        which would result in a call to the `Analytics` class as
+
+            import nova.api.analytics
+            analytics.Analytics(app_from_paste, redis_host='127.0.0.1')
+
+        You could of course re-implement the `factory` method in subclasses,
+        but using the kwarg passing it shouldn't be necessary.
+
+        """
+        def _factory(app):
+            return cls(app, **local_config)
+        return _factory
+
     def __init__(self, application):
         self.application = application
 
@@ -403,3 +460,64 @@ 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)