Add Fetcher documentation

Add a Fetcher documentation section in admin/configuration/
with details about configuration of all currently available fetchers.
This patch covers options of the new Prometheus fetcher too.

Change-Id: Id1dae663aeddbd0564ea798654ce339ef4a3c9f9
Story: 2005427
Task: 30460

doc/source/admin/configuration/fetcher.rst

@@ -0,0 +1,91 @@
+======================
+ Fetcher configuration
+======================
+
+Backend option
+==============
+
+``backend`` is a common option specified in the ``[fetcher]`` section of
+the configuration file. It defaults to ``keystone`` and specifies the driver
+to be used for fetching the list of scopes to rate.
+
+Fetcher-specific options
+========================
+
+Fetcher-specific options must be specified in the
+``fetcher_{fetcher_name}`` section of ``cloudkitty.conf``.
+
+Gnocchi
+-------
+
+Section ``fetcher_gnocchi``.
+
+* ``scope_attribute``: Defaults to ``project_id``. Attribute from which
+  scope_ids should be collected.
+
+* ``resource_types``: Defaults to ``[generic]``. List of gnocchi resource
+  types. All if left blank.
+
+* ``gnocchi_auth_type``: Defaults to ``keystone``. Defines what authentication
+  method should be used by the gnocchi fetcher. Must be one of ``basic``
+  (for gnocchi basic authentication) or ``keystone`` (for classic keystone
+  authentication). If ``keystone`` is chosen, credentials can be specified
+  in a section pointed at by the ``auth_section`` parameter.
+
+* ``gnocchi_user``: For gnocchi basic authentication only. The gnocchi user.
+
+* ``gnocchi_endpoint``: For gnocchi basic authentication only. The gnocchi
+  endpoint.
+
+* ``interface``: Defaults to ``internalURL``. For keystone authentication only.
+  The interface to use for keystone URL discovery.
+
+* ``region_name``: Defaults to ``RegionOne``. For keystone authentication only.
+  Region name.
+
+
+Keystone
+--------
+
+Section ``fetcher_keystone``.
+
+* ``keystone_version``: Defaults to ``2``. Keystone version to use.
+
+* ``auth_section``: If the ``auth_section`` option is defined then all the
+  options declared in the target section will be used in order to fetch scopes
+  through Keystone service.
+
+If ``auth_section`` option is not defined then you can configure Keystone
+fetcher using regular Keystone authentication options as found here:
+:doc:`configuration`.
+
+
+Prometheus
+----------
+
+Section ``fetcher_prometheus``.
+
+* ``metric``: Metric from which scope_ids should be requested.
+
+* ``scope_attribute``: Defaults to ``project_id``. Attribute from which
+  scope_ids should be requested.
+
+* ``filters``: Optional key-value dictionary to use additional metadata to
+  filter out some of the Prometheus service response.
+
+* ``prometheus_url``: Prometheus HTTP API URL.
+
+* ``prometheus_user``: For HTTP basic authentication. The username.
+
+* ``prometheus_password``: For HTTP basic authentication. The password.
+
+* ``cafile``: Option to allow custom certificate authority file.
+
+* ``insecure``: Option to explicitly allow untrusted HTTPS connections.
+
+Source
+------
+
+Section ``fetcher_source``.
+
+* ``sources``: Explicit list of scope_ids.

doc/source/admin/configuration/index.rst

@@ -6,6 +6,7 @@ Configuration Guide
    :glob:
 
    configuration
+   fetcher
    collector
    storage
    policy