Add the describe of uWSGI to run Gnocchi API

Gnocchi API coundn't be use if we don't install and configure uwsgi
or other HTTP daemon. And gnocchi install guide didn't describe
those.

Add the describe of installing uWSGI and the brief relationship
between uWSGI and Gnocchi API. And tell the reader that they can
also use Apache httpd and mod_wsgi, or any other HTTP daemon to
run Gnocchi API.

Closes-Bug: #1750933
Change-Id: Iba8c1fe7a64569de4ca366251c495731a8d7a779

doc/source/install/install-base-obs.rst

@@ -32,6 +32,22 @@ Install Gnocchi
       Depending on your environment size, consider installing Gnocchi
       separately as it makes extensive use of the cpu.
 
+#. Install the uWSGI packages. The following method uses operating system
+   provided packages. Another alternative would be to use pip(or pip3,
+   depending on the distribution); using pip is not described in this doc:
+
+   .. code-block:: console
+
+      # zypper install uwsgi-plugin-python3 uwsgi
+
+   .. note::
+
+      Since the provided gnocchi-api wraps around uwsgi, you need to
+      make sure that uWSGI is installed if you want to use gnocchi-api
+      to run Gnocchi API.
+      As Gnocchi API tier runs using WSGI, it can also alternatively
+      be run using Apache httpd and mod_wsgi, or any other HTTP daemon.
+
 .. include:: install-gnocchi.inc
 
 Finalize Gnocchi installation

doc/source/install/install-base-rdo.rst

@@ -32,6 +32,22 @@ Install Gnocchi
       Depending on your environment size, consider installing Gnocchi
       separately as it makes extensive use of the cpu.
 
+#. Install the uWSGI packages. The following method uses operating system
+   provided packages. Another alternative would be to use pip(or pip3,
+   depending on the distribution); using pip is not described in this doc:
+
+   .. code-block:: console
+
+      # yum install uwsgi-plugin-common uwsgi-plugin-python3 uwsgi
+
+   .. note::
+
+      Since the provided gnocchi-api wraps around uwsgi, you need to
+      make sure that uWSGI is installed if you want to use gnocchi-api
+      to run Gnocchi API.
+      As Gnocchi API tier runs using WSGI, it can also alternatively
+      be run using Apache httpd and mod_wsgi, or any other HTTP daemon.
+
 .. include:: install-gnocchi.inc
 
 Finalize Gnocchi installation

doc/source/install/install-base-ubuntu.rst

@@ -31,6 +31,22 @@ Install Gnocchi
       Depending on your environment size, consider installing Gnocchi
       separately as it makes extensive use of the cpu.
 
+#. Install the uWSGI packages. The following method uses operating system
+   provided packages. Another alternative would be to use pip(or pip3,
+   depending on the distribution); using pip is not described in this doc:
+
+   .. code-block:: console
+
+      # apt-get install uwsgi-plugin-python3 uwsgi
+
+   .. note::
+
+      Since the provided gnocchi-api wraps around uwsgi, you need to
+      make sure that uWSGI is installed if you want to use gnocchi-api
+      to run Gnocchi API.
+      As Gnocchi API tier runs using WSGI, it can also alternatively
+      be run using Apache httpd and mod_wsgi, or any other HTTP daemon.
+
 .. include:: install-gnocchi.inc
 
 Finalize Gnocchi installation

doc/source/install/install-gnocchi.inc

@@ -1,4 +1,4 @@
-2. Create the database for Gnocchi's indexer:
+3. Create the database for Gnocchi's indexer:
 
    * Use the database access client to connect to the database
      server as the ``root`` user:
@@ -26,7 +26,7 @@
 
    * Exit the database access client.
 
-3. Edit the ``/etc/gnocchi/gnocchi.conf`` file and add Keystone options:
+4. Edit the ``/etc/gnocchi/gnocchi.conf`` file and add Keystone options:
 
    * In the ``[api]`` section, configure gnocchi to use keystone:
 
@@ -34,6 +34,8 @@
 
         [api]
         auth_mode = keystone
+        port = 8041
+        uwsgi_mode = http-socket
 
    * In the ``[keystone_authtoken]`` section, configure keystone
      authentication:
@@ -78,7 +80,7 @@
         file_basepath = /var/lib/gnocchi
         driver = file
 
-4. Initialize Gnocchi:
+5. Initialize Gnocchi:
 
    .. code-block:: console