Expose sample config opts for http-proxy-to-wsgi

Allow sample config generators to retrieve the options for the
http-proxy-to-wsgi middleware.

Change-Id: I862c9238b791098c9bb9ce4558db5b21dad14a30
Closes-Bug: #1590218

oslo_middleware/opts.py

@@ -17,7 +17,8 @@ __all__ = [
     'list_opts',
     'list_opts_sizelimit',
     'list_opts_ssl',
-    'list_opts_cors'
+    'list_opts_cors',
+    'list_opts_http_proxy_to_wsgi',
 ]
 
 
@@ -25,6 +26,7 @@ import copy
 import itertools
 
 from oslo_middleware import cors
+from oslo_middleware import http_proxy_to_wsgi
 from oslo_middleware import sizelimit
 from oslo_middleware import ssl
 
@@ -53,6 +55,7 @@ def list_opts():
             list_opts_sizelimit(),
             list_opts_ssl(),
             list_opts_cors(),
+            list_opts_http_proxy_to_wsgi(),
         )
     )
 
@@ -128,3 +131,27 @@ def list_opts_cors():
         ('cors', copy.deepcopy(cors.CORS_OPTS)),
         ('cors.subdomain', copy.deepcopy(cors.CORS_OPTS))
     ]
+
+
+def list_opts_http_proxy_to_wsgi():
+    """Return a list of oslo.config options for http_proxy_to_wsgi.
+
+    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.middleware' 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(http_proxy_to_wsgi.OPTS)),
+    ]

setup.cfg

@@ -28,6 +28,7 @@ oslo.config.opts =
     oslo.middleware.cors = oslo_middleware.opts:list_opts_cors
     oslo.middleware.sizelimit = oslo_middleware.opts:list_opts_sizelimit
     oslo.middleware.ssl = oslo_middleware.opts:list_opts_ssl
+    oslo.middleware.http_proxy_to_wsgi = oslo_middleware.opts:list_opts_http_proxy_to_wsgi
 
 oslo.middleware.healthcheck =
     disable_by_file = oslo_middleware.healthcheck.disable_by_file:DisableByFileHealthcheck