SCSS $webroot should inherit from settings.py

There is double maintenance right now when you change the STATIC_URL
via settings.py, you must also use a custom theme to have access to
also change $webroot within the SCSS to serve font-awesome from a
custom location.

This patch makes the STATIC_URL available by default in the SCSS
namespace through variable $static_url.

Also, it was being called $webroot in the SCSS, but it should
actually be called $static_url since it should map directly to
settings.py's STATIC_URL.

Change-Id: I1ee40652f8110b176f45b8811f0e0197789a73da
Closes-Bug: #1478794

doc/source/topics/settings.rst

@@ -1067,18 +1067,6 @@ the web server.
 For example, if you're accessing the Dashboard via
 https://<your server>/dashboard, you would set this to ``"/dashboard/"``.
 
-Additionally, setting the ``"$webroot"`` SCSS variable is required. You
-can change this directly in
-``"openstack_dashboard/static/dashboard/scss/_variables.scss"`` or in the
-``"_variables.scss"`` file in your custom theme. For more information on
-custom themes, see: ``"CUSTOM_THEME_PATH"``.
-
-Make sure you run ``python manage.py collectstatic`` and
-``python manage.py compress`` after you change the ``_variables.scss`` file.
-
-For your convenience, a custom theme for only setting the web root has been
-provided see: ``"/horizon/openstack_dashboard/themes/webroot"``
-
 .. note::
 
     Additional settings may be required in the config files of your webserver
@@ -1125,6 +1113,13 @@ webserver configuration should be updated to match.
 
     The value for STATIC_URL must end in '/'.
 
+This value is also available in the scss namespace with the variable name
+$static_url.  Make sure you run ``python manage.py collectstatic`` and
+``python manage.py compress`` after any changes to this value in settings.py.
+
+For your convenience, a custom theme for only setting the static url has been
+provided see: ``"/horizon/openstack_dashboard/themes/webroot"``
+
 For more information see:
 https://docs.djangoproject.com/en/1.7/ref/settings/#static-url
 

horizon/utils/scss_filter.py

@@ -0,0 +1,43 @@
+# (c) Copyright 2015 Hewlett-Packard Development Company, L.P.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from django.conf import settings
+
+from django_pyscss.compressor import DjangoScssFilter
+from django_pyscss import DjangoScssCompiler
+
+from scss.namespace import Namespace
+from scss.types import String
+
+import six
+
+
+class HorizonScssFilter(DjangoScssFilter):
+    def __init__(self, *args, **kwargs):
+        super(HorizonScssFilter, self).__init__(*args, **kwargs)
+
+        self.namespace = Namespace()
+
+        # Add variables to the SCSS Global Namespace Here
+        self.namespace.set_variable(
+            '$static_url',
+            String(six.text_type(getattr(settings, 'STATIC_URL', '/static/')))
+        )
+
+    # Create a compiler with the right namespace
+    @property
+    def compiler(self):
+        return DjangoScssCompiler(
+            namespace=self.namespace
+        )

openstack_dashboard/settings.py

@@ -141,7 +141,7 @@ STATICFILES_FINDERS = (
 )
 
 COMPRESS_PRECOMPILERS = (
-    ('text/scss', 'django_pyscss.compressor.DjangoScssFilter'),
+    ('text/scss', 'horizon.utils.scss_filter.HorizonScssFilter'),
 )
 
 COMPRESS_CSS_FILTERS = (

openstack_dashboard/static/dashboard/scss/_variables.scss

@@ -2,10 +2,10 @@
 to our variables */
 @import "/custom/variables";
 
-
+/* When used with Horizon via Django, this value is set automatically from
-/* This variable can be used to change the web root of horizon
+   settings.py and is added dynamically to the namespace through
-default value is already '/' */
+   horizon/utils/scss_filter.py */
-$webroot: "" !default;
+$static_url: "/static/" !default;
 
 
 /* Horizon Custom Variables */
@@ -59,7 +59,7 @@ $rbrowser-footer-background-color: #f1f1f1;
 //       .table-striped-datatable styles.
 
 // Font-awesome path to the icon fonts
-$fa-font-path: $webroot + "/static/horizon/lib/font-awesome/fonts";
+$fa-font-path: $static_url + "horizon/lib/font-awesome/fonts";
 
 /* Charts */
 

openstack_dashboard/themes/webroot/_variables.scss

@@ -1,5 +1,5 @@
 /* This variable changes the web root of horizon to /dashboard rather
 than the default '/' */
-$webroot: "/dashboard";
+$static_url: "/dashboard/static/";
 
 @import "../themes/default/variables";