Support to move the horizon relative to web root

When deploying Horizon, on a web server, where other applications
are used, it's quite handy to be able to move Horizon around quickly.
This change introduces a single Variable WEBROOT to achieve this.

Implements: blueprint shared-webserver

Change-Id: Ic731f6754e233b328a8dbe7026b1d7417620fd66

doc/source/topics/settings.rst

@@ -822,6 +822,19 @@ Disable SSL certificate checks in the OpenStack clients (useful for self-signed
 certificates).
 
 
+``OPENSTACK_TOKEN_HASH_ALGORITHM``
+----------------------------------
+
+.. versionadded:: 2014.2(Juno)
+
+Default: ``"md5"``
+
+The hash algorithm to use for authentication tokens. This must match the hash
+algorithm that the identity (Keystone) server and the auth_token middleware
+are using. Allowed values are the algorithms supported by Python's hashlib
+library.
+
+
 ``POLICY_FILES``
 ----------------
 
@@ -877,17 +890,21 @@ To disable these extensions set the permission to something
 unusable such as ``[!]``.
 
 
-``OPENSTACK_TOKEN_HASH_ALGORITHM``
-----------------------------------
+``WEBROOT``
+-----------
+
+.. versionadded:: 2015.1(Kilo)
+
+Default: ``"/"``
+
+Specifies the location where the access to the dashboard is configured in
+the web server.
+
+E.g. if you're accessing the Dashboard via https://<your server>/horizon, you'd
+set this to ``"/horizon"``.
 
-.. versionadded:: 2014.2(Juno)
 
-Default: ``"md5"``
 
-The hash algorithm to use for authentication tokens. This must match the hash
-algorithm that the identity (Keystone) server and the auth_token middleware
-are using. Allowed values are the algorithms supported by Python's hashlib
-library.
 
 Django Settings (Partial)
 =========================

openstack_dashboard/local/local_settings.py.example

@@ -7,6 +7,19 @@ from openstack_dashboard import exceptions
 DEBUG = True
 TEMPLATE_DEBUG = DEBUG
 
+
+# WEBROOT is the location relative to Webserver root
+# should end with a slash.
+WEBROOT = '/'
+# LOGIN_URL = WEBROOT + 'auth/login/'
+# LOGOUT_URL = WEBROOT + 'auth/logout/'
+#
+# LOGIN_REDIRECT_URL can be used as an alternative for
+# HORIZON_CONFIG.user_home, if user_home is not set.
+# Do not set it to '/home/', as this will cause circular redirect loop
+# LOGIN_REDIRECT_URL = WEBROOT
+
+
 # Required for Django 1.5.
 # If horizon is running in production (DEBUG is False), set this
 # with the list of host/domain names that the application can serve.

openstack_dashboard/settings.py

@@ -41,12 +41,11 @@ TEMPLATE_DEBUG = DEBUG
 
 SITE_BRANDING = 'OpenStack Dashboard'
 
-LOGIN_URL = '/auth/login/'
-LOGOUT_URL = '/auth/logout/'
-# LOGIN_REDIRECT_URL can be used as an alternative for
-# HORIZON_CONFIG.user_home, if user_home is not set.
-# Do not set it to '/home/', as this will cause circular redirect loop
-LOGIN_REDIRECT_URL = '/'
+WEBROOT = '/'
+LOGIN_URL = None
+LOGOUT_URL = None
+LOGIN_REDIRECT_URL = None
+
 
 MEDIA_ROOT = os.path.abspath(os.path.join(ROOT_PATH, '..', 'media'))
 MEDIA_URL = '/media/'
@@ -257,6 +256,16 @@ try:
 except ImportError:
     logging.warning("No local_settings file found.")
 
+if not WEBROOT.endswith('/'):
+    WEBROOT += '/'
+if LOGIN_URL is None:
+    LOGIN_URL = WEBROOT + 'auth/login/'
+if LOGOUT_URL is None:
+    LOGOUT_URL = WEBROOT + 'auth/logout/'
+if LOGIN_REDIRECT_URL is None:
+    LOGIN_REDIRECT_URL = WEBROOT
+
+
 # Load the pluggable dashboard settings
 import openstack_dashboard.enabled
 import openstack_dashboard.local.enabled