Merge pull request #11400 from edx/PERF-258

Add the ability to exclude files from URL canonicalization.

common/djangoapps/static_replace/__init__.py

@@ -5,7 +5,7 @@ from django.contrib.staticfiles.storage import staticfiles_storage
 from django.contrib.staticfiles import finders
 from django.conf import settings
 
-from static_replace.models import AssetBaseUrlConfig
+from static_replace.models import AssetBaseUrlConfig, AssetExcludedExtensionsConfig
 from xmodule.modulestore.django import modulestore
 from xmodule.modulestore import ModuleStoreEnum
 from xmodule.contentstore.content import StaticContent
@@ -182,7 +182,8 @@ def replace_static_urls(text, data_directory=None, course_id=None, static_asset_
                 # if not, then assume it's courseware specific content and then look in the
                 # Mongo-backed database
                 base_url = AssetBaseUrlConfig.get_base_url()
-                url = StaticContent.get_canonicalized_asset_path(course_id, rest, base_url)
+                excluded_exts = AssetExcludedExtensionsConfig.get_excluded_extensions()
+                url = StaticContent.get_canonicalized_asset_path(course_id, rest, base_url, excluded_exts)
 
                 if AssetLocator.CANONICAL_NAMESPACE in url:
                     url = url.replace('block@', 'block/', 1)

common/djangoapps/static_replace/migrations/0002_assetexcludedextensionsconfig.py

+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+from django.conf import settings
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('static_replace', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='AssetExcludedExtensionsConfig',
+            fields=[
+                ('id', models.AutoField(verbose_name='ID', serialize=False, auto_created=True, primary_key=True)),
+                ('change_date', models.DateTimeField(auto_now_add=True, verbose_name='Change date')),
+                ('enabled', models.BooleanField(default=False, verbose_name='Enabled')),
+                ('excluded_extensions', models.TextField(default=b'html', help_text=b'The file extensions to exclude from canonicalization.  No leading period required. Values should be space separated i.e. "html svg css"')),
+                ('changed_by', models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, editable=False, to=settings.AUTH_USER_MODEL, null=True, verbose_name='Changed by')),
+            ],
+        ),
+    ]

common/djangoapps/static_replace/models.py

@@ -27,3 +27,28 @@ class AssetBaseUrlConfig(ConfigurationModel):
 
     def __unicode__(self):
         return unicode(repr(self))
+
+
+class AssetExcludedExtensionsConfig(ConfigurationModel):
+    """Configuration for the the excluded file extensions when canonicalizing static asset paths."""
+
+    class Meta(object):
+        app_label = 'static_replace'
+
+    excluded_extensions = TextField(
+        default='html',
+        help_text='The file extensions to exclude from canonicalization.  No leading period required. ' +
+        'Values should be space separated i.e. "html svg css"'
+    )
+
+    @classmethod
+    def get_excluded_extensions(cls):
+        """Gets the excluded file extensions when canonicalizing static asset paths"""
+        add_period = lambda x: '.' + x
+        return map(add_period, cls.current().excluded_extensions.split())
+
+    def __repr__(self):
+        return '<AssetExcludedExtensionsConfig(extensions={})>'.format(self.get_excluded_extensions().split())
+
+    def __unicode__(self):
+        return unicode(repr(self))

common/lib/xmodule/xmodule/contentstore/content.py

@@ -168,7 +168,7 @@ class StaticContent(object):
             return StaticContent.compute_location(course_key, path)
 
     @staticmethod
-    def get_canonicalized_asset_path(course_key, path, base_url):
+    def get_canonicalized_asset_path(course_key, path, base_url, excluded_exts):
         """
         Returns a fully-qualified path to a piece of static content.
 
@@ -199,17 +199,22 @@ class StaticContent(object):
             # If we can't find the item, just treat it as if it's locked.
             serve_from_cdn = False
 
+        # See if this is an allowed file extension to serve.  Some files aren't served through the
+        # CDN in order to avoid same-origin policy/CORS-related issues.
+        if any(relative_path.lower().endswith(excluded_ext.lower()) for excluded_ext in excluded_exts):
+            serve_from_cdn = False
+
         # Update any query parameter values that have asset paths in them. This is for assets that
         # require their own after-the-fact values, like a Flash file that needs the path of a config
         # file passed to it e.g. /static/visualization.swf?configFile=/static/visualization.xml
         query_params = parse_qsl(query_string)
         updated_query_params = []
-        for query_name, query_value in query_params:
-            if query_value.startswith("/static/"):
-                new_query_value = StaticContent.get_canonicalized_asset_path(course_key, query_value, base_url)
-                updated_query_params.append((query_name, new_query_value))
+        for query_name, query_val in query_params:
+            if query_val.startswith("/static/"):
+                new_val = StaticContent.get_canonicalized_asset_path(course_key, query_val, base_url, excluded_exts)
+                updated_query_params.append((query_name, new_val))
             else:
-                updated_query_params.append((query_name, query_value))
+                updated_query_params.append((query_name, query_val))
 
         serialized_asset_key = StaticContent.serialize_asset_key_with_slash(asset_key)
         base_url = base_url if serve_from_cdn else ''