Allow to get option from paste-deploy

This change allows any middleware that use oslo.config to
be configured via paste-deploy, like the cors does.

Related-bug: #1482086
Change-Id: Ibb3e951b45b51c9bc602c9113df18a58226d92d1

3 files changed, 57 insertions, 0 deletions

diff --git a/doc/source/healthcheck_plugins.rst b/doc/source/healthcheck_plugins.rst
index c3e43ec..04683cc 100644
--- a/doc/source/healthcheck_plugins.rst
+++ b/doc/source/healthcheck_plugins.rst
@@ -2,5 +2,8 @@
  Healthcheck middleware plugins
 ================================
 
+.. automodule:: oslo_middleware.healthcheck
+   :members:
+
 .. automodule:: oslo_middleware.healthcheck.disable_by_file
    :members:
diff --git a/doc/source/index.rst b/doc/source/index.rst
index ebca9f6..055768d 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -10,4 +10,5 @@ Contents
    api
    healthcheck_plugins
    cors
+   oslo_config
    contributing
diff --git a/doc/source/oslo_config.rst b/doc/source/oslo_config.rst
new file mode 100644
index 0000000..09c83c6
--- /dev/null
+++ b/doc/source/oslo_config.rst
@@ -0,0 +1,53 @@
+=============================
+Middlewares and configuration
+=============================
+
+Middlewares can be configured in multiple fashion depending of the
+application needs. Here is some use-cases: 
+
+Configuration from the application
+----------------------------------
+
+The application code will looks like::
+
+    from oslo_middleware import sizelimit
+    from oslo_config import cfg
+
+    conf = cfg.ConfigOpts()
+    app = sizelimit.RequestBodySizeLimiter(your_wsgi_application, conf)
+
+
+Configuration with paste-deploy and the oslo.config
+---------------------------------------------------
+
+The paste filter (in /etc/my_app/api-paste.ini) will looks like::
+
+    [filter:sizelimit]
+    paste.filter_factory = oslo_middleware.sizelimit:RequestBodySizeLimiter.factory
+    # In case of the application doesn't use the global oslo.config 
+    # object. The middleware must known the app name to load 
+    # the application configuration, by setting this:
+    #  oslo_config_project = my_app
+
+The oslo.config file of the application (eg: /etc/my_app/my_app.conf) will looks like::
+
+    [oslo_middleware]
+    max_request_body_size=1000
+
+
+Configuration with pastedeploy only
+-----------------------------------
+
+The paste filter (in /etc/my_app/api-paste.ini) will looks like::
+
+    [filter:sizelimit]
+    paste.filter_factory = oslo_middleware.sizelimit:RequestBodySizeLimiter.factory
+    max_request_body_size=1000
+
+This will override any configuration done via oslo.config
+
+
+.. note::
+
+    healtcheck middleware does not yet use oslo.config, see :doc:`healthcheck_plugins`
+