render custom HTML for error pages

IPython/html/base/handlers.py

@@ -24,7 +24,13 b' import os'
 import stat
 import sys
 import traceback
+try:
+    # py3
+    from http.client import responses
+except ImportError:
+    from httplib import responses
 
+from jinja2 import TemplateNotFound
 from tornado import web
 
 try:
@@ -44,14 +50,7 b" UF_HIDDEN = getattr(stat, 'UF_HIDDEN', 32768)"
 # Top-level handlers
 #-----------------------------------------------------------------------------
 
-class RequestHandler(web.RequestHandler):
-    """RequestHandler with default variable setting."""
-
-    def render(*args, **kwargs):
-        kwargs.setdefault('message', '')
-        return web.RequestHandler.render(*args, **kwargs)
-
-class AuthenticatedHandler(RequestHandler):
+class AuthenticatedHandler(web.RequestHandler):
     """A RequestHandler with an authenticated user."""
 
     def clear_login_cookie(self):
@@ -209,6 +208,45 b' class IPythonHandler(AuthenticatedHandler):'
             raise web.HTTPError(400, u'Invalid JSON in body of request')
         return model
 
+    def get_error_html(self, status_code, **kwargs):
+        """render custom error pages"""
+        exception = kwargs.get('exception')
+        message = ''
+        status_message = responses.get(status_code, 'Unknown')
+        if exception:
+            # get the custom message, if defined
+            try:
+                message = exception.log_message % exception.args
+            except Exception:
+                pass
+            
+            # construct the custom reason, if defined
+            reason = getattr(exception, 'reason', '')
+            if reason:
+                status_message = reason
+        
+        # build template namespace
+        ns = dict(
+            status_code=status_code,
+            status_message=status_message,
+            message=message,
+            exception=exception,
+        )
+        
+        # render the template
+        try:
+            html = self.render_template('%s.html' % status_code, **ns)
+        except TemplateNotFound:
+            self.log.debug("No template for %d", status_code)
+            html = self.render_template('error.html', **ns)
+        return html
+
+
+class Template404(IPythonHandler):
+    """Render our 404 template"""
+    def prepare(self):
+        raise web.HTTPError(404)
+
 
 class AuthenticatedFileHandler(IPythonHandler, web.StaticFileHandler):
     """static files should only be accessible when logged in"""

IPython/html/notebookapp.py

@@ -61,6 +61,7 b' from tornado import web'
 
 # Our own libraries
 from IPython.html import DEFAULT_STATIC_FILES_PATH
+from .base.handlers import Template404
 
 from .services.kernels.kernelmanager import MappingKernelManager
 from .services.notebooks.nbmanager import NotebookManager
@@ -208,6 +209,8 b' class NotebookWebApplication(web.Application):'
             pattern = url_path_join(settings['base_project_url'], handler[0])
             new_handler = tuple([pattern] + list(handler[1:]))
             new_handlers.append(new_handler)
+        # add 404 on the end, which will catch everything that falls through
+        new_handlers.append((r'(.*)', Template404))
         return new_handlers