cache control on static files

same principle as used in IPython,
slightly different implementation.

jupyterhub/app.py

@@ -41,7 +41,9 @@ from IPython.config import Application, catch_config_error
 
 here = os.path.dirname(__file__)
 
+import jupyterhub
 from . import handlers, apihandlers
+from .handlers.static import CacheControlStaticFilesHandler
 
 from . import orm
 from ._data import DATA_FILES_PATH
@@ -201,7 +203,6 @@ class JupyterHub(Application):
         help="The base URL of the entire application"
     )
     
-    
     jinja_environment_options = Dict(config=True,
         help="Supply extra arguments that will be passed to Jinja environment."
     )
@@ -701,6 +702,14 @@ class JupyterHub(Application):
         login_url = self.authenticator.login_url(base_url)
         logout_url = self.authenticator.logout_url(base_url)
         
+        # if running from git, disable caching of require.js
+        # otherwise cache based on server start time
+        parent = os.path.dirname(os.path.dirname(jupyterhub.__file__))
+        if os.path.isdir(os.path.join(parent, '.git')):
+            version_hash = ''
+        else:
+            version_hash=datetime.now().strftime("%Y%m%d%H%M%S"),
+        
         settings = dict(
             config=self.config,
             log=self.log,
@@ -716,8 +725,10 @@ class JupyterHub(Application):
             logout_url=logout_url,
             static_path=os.path.join(self.data_files_path, 'static'),
             static_url_prefix=url_path_join(self.hub.server.base_url, 'static/'),
+            static_handler_class=CacheControlStaticFilesHandler,
             template_path=template_path,
             jinja2_env=jinja_env,
+            version_hash=version_hash,
         )
         # allow configured settings to have priority
         settings.update(self.tornado_settings)

jupyterhub/handlers/base.py

@@ -38,7 +38,11 @@ class BaseHandler(RequestHandler):
     @property
     def base_url(self):
         return self.settings.get('base_url', '/')
-
+    
+    @property
+    def version_hash(self):
+        return self.settings.get('version_hash', '')
+    
     @property
     def db(self):
         return self.settings['db']
@@ -240,6 +244,7 @@ class BaseHandler(RequestHandler):
             login_url=self.settings['login_url'],
             logout_url=self.settings['logout_url'],
             static_url=self.static_url,
+            version_hash=self.version_hash,
         )
 
     def write_error(self, status_code, **kwargs):

jupyterhub/handlers/static.py

@@ -0,0 +1,14 @@
+# Copyright (c) Jupyter Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+from tornado.web import StaticFileHandler
+
+class CacheControlStaticFilesHandler(StaticFileHandler):
+    """StaticFileHandler subclass that sets Cache-Control: no-cache without `?v=`
+    
+    rather than relying on default browser cache behavior.
+    """
+    def set_extra_headers(self, path):
+        if "v" not in self.request.arguments:
+            self.add_header("Cache-Control", "no-cache")
+    

share/jupyter/hub/templates/page.html

@@ -35,6 +35,9 @@
     <script src="{{static_url("components/requirejs/require.js") }}" type="text/javascript" charset="utf-8"></script>
     <script>
       require.config({
+          {% if version_hash %}
+          urlArgs: "v={{version_hash}}",
+          {% endif %}
           baseUrl: '{{static_url("js", include_version=False)}}',
           paths: {
             components: '../components',