Expose sizelimit option to config generator

* Adding a group name to prevent collision with keystone
  middleware library option
* Adds an opts module for the config generator to use.
* Makes the option in sizelimit private since we don't want consumers
  using them directly.
* Moves the options to an oslo_middleware group with appropriate
  deprecated_opts settings to keep existing configs working.

Closes-Bug: #1368490
Change-Id: I72263bd363a79275a314de727a04277276866565

4 files changed, 70 insertions, 12 deletions

diff --git a/oslo/middleware/opts.py b/oslo/middleware/opts.py
new file mode 100644
index 0000000..3cc035f
--- /dev/null
+++ b/oslo/middleware/opts.py
@@ -0,0 +1,45 @@
+# Copyright 2014 IBM Corp.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+
+__all__ = [
+    'list_opts',
+]
+
+
+import copy
+
+from oslo.middleware import sizelimit
+
+
+def list_opts():
+    """Return a list of oslo.config options available in the library.
+
+    The returned list includes all oslo.config options which may be registered
+    at runtime by the library.
+
+    Each element of the list is a tuple. The first element is the name of the
+    group under which the list of elements in the second element will be
+    registered. A group name of None corresponds to the [DEFAULT] group in
+    config files.
+
+    This function is also discoverable via the 'oslo.concurrency' entry point
+    under the 'oslo.config.opts' namespace.
+
+    The purpose of this is to allow tools like the Oslo sample config file
+    generator to discover the options exposed to users by this library.
+
+    :returns: a list of (group_name, opts) tuples
+    """
+    return [('oslo_middleware', copy.deepcopy(sizelimit._opts))]
\ No newline at end of file
diff --git a/oslo/middleware/sizelimit.py b/oslo/middleware/sizelimit.py
index 3108c72..3caa8b1 100644
--- a/oslo/middleware/sizelimit.py
+++ b/oslo/middleware/sizelimit.py
@@ -18,6 +18,7 @@ Request Body limiting middleware.
 """
 
 from oslo.config import cfg
+from oslo.config import cfgfilter
 import webob.dec
 import webob.exc
 
@@ -25,15 +26,22 @@ from oslo.middleware import base
 from oslo.middleware.i18n import _
 
 
-# default request size is 112k
-max_req_body_size = cfg.IntOpt('max_request_body_size',
-                               deprecated_name='osapi_max_request_body_size',
-                               default=114688,
-                               help='The maximum body size for each '
-                                    ' request, in bytes.')
+_oldopts = [cfg.DeprecatedOpt('osapi_max_request_body_size',
+                              group='DEFAULT'),
+            cfg.DeprecatedOpt('max_request_body_size',
+                              group='DEFAULT')]
 
-CONF = cfg.CONF
-CONF.register_opt(max_req_body_size)
+_opts = [
+    # default request size is 112k
+    cfg.IntOpt('max_request_body_size',
+               default=114688,
+               help='The maximum body size for each '
+                    ' request, in bytes.',
+               deprecated_opts=_oldopts)
+]
+
+CONF = cfgfilter.ConfigFilter(cfg.CONF)
+CONF.register_opts(_opts, group='oslo_middleware')
 
 
 class LimitingReader(object):
@@ -71,12 +79,12 @@ class RequestBodySizeLimiter(base.Middleware):
 
     @webob.dec.wsgify
     def __call__(self, req):
+        max_size = CONF.oslo_middleware.max_request_body_size
         if (req.content_length is not None and
-                req.content_length > CONF.max_request_body_size):
+                req.content_length > max_size):
             msg = _("Request is too large.")
             raise webob.exc.HTTPRequestEntityTooLarge(explanation=msg)
         if req.content_length is None and req.is_body_readable:
-            limiter = LimitingReader(req.body_file,
-                                     CONF.max_request_body_size)
+            limiter = LimitingReader(req.body_file, max_size)
             req.body_file = limiter
         return self.application
diff --git a/setup.cfg b/setup.cfg
index 4267183..7cffaa1 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -25,6 +25,10 @@ packages =
 namespace_packages =
     oslo
 
+[entry_points]
+oslo.config.opts =
+    oslo.middleware = oslo.middleware.opts:list_opts
+
 [build_sphinx]
 source-dir = doc/source
 build-dir = doc/build
diff --git a/tests/test_sizelimit.py b/tests/test_sizelimit.py
index 0f813d8..89f655a 100644
--- a/tests/test_sizelimit.py
+++ b/tests/test_sizelimit.py
@@ -70,8 +70,9 @@ class TestRequestBodySizeLimiter(test_base.BaseTestCase):
 
     def setUp(self):
         super(TestRequestBodySizeLimiter, self).setUp()
+        fixture = self.useFixture(config.Config(sizelimit.CONF))
         self.MAX_REQUEST_BODY_SIZE = \
-            self.useFixture(config.Config()).conf.max_request_body_size
+            fixture.conf.oslo_middleware.max_request_body_size
 
         @webob.dec.wsgify()
         def fake_app(req):