# HG changeset patch
# User Julien Cristau <julien.cristau@logilab.fr>
# Date 1406641504 -7200
# Node ID 6bcb460826ccb098ffa28cbf2b09b57ce36a0ac1
# Parent  586d0e5270520e0ec7fa1cf67913717b013b9c6a
[web] set Vary response header to "Accept-Language" when using content negotiation

This is slightly annoying because the response actually only varies
based on the language we decide to send, which has much fewer possible
values than Accept-Language, but that's not in the request, so we can't
easily use it.  Deployments using varnish or similar and controlling the
set of available languages will likely want to override this to allow
reasonable amounts of caching.

Closes #2105812

diff -r 586d0e527052 -r 6bcb460826cc web/request.py
--- a/web/request.py	Tue Jul 29 16:27:11 2014 +0200
+++ b/web/request.py	Tue Jul 29 15:45:04 2014 +0200
@@ -139,6 +139,11 @@
         self.setup_params(form)
         #: received body
         self.content = StringIO()
+        # prepare output header
+        #: Header used for the final response
+        self.headers_out = Headers()
+        #: HTTP status use by the final response
+        self.status_out  = 200
         # set up language based on request headers or site default (we don't
         # have a user yet, and might not get one)
         self.set_user_language(None)
@@ -152,11 +157,6 @@
         #: page id, set by htmlheader template
         self.pageid = None
         self._set_pageid()
-        # prepare output header
-        #: Header used for the final response
-        self.headers_out = Headers()
-        #: HTTP status use by the final response
-        self.status_out  = 200
 
     def _set_pageid(self):
         """initialize self.pageid
@@ -1001,6 +1001,7 @@
                 pass
         if vreg.config.get('language-negociation', False):
             # 2. http accept-language
+            self.headers_out.addHeader('Vary', 'Accept-Language')
             for lang in self.header_accept_language():
                 if lang in self.translations:
                     self.set_language(lang)
diff -r 586d0e527052 -r 6bcb460826cc web/test/unittest_web.py
--- a/web/test/unittest_web.py	Tue Jul 29 16:27:11 2014 +0200
+++ b/web/test/unittest_web.py	Tue Jul 29 15:45:04 2014 +0200
@@ -101,9 +101,13 @@
         headers = {'Accept-Language': 'fr'}
         webreq = self.web_request(headers=headers)
         self.assertIn('lang="fr"', webreq.read())
+        vary = [h.lower().strip() for h in webreq.getheader('Vary').split(',')]
+        self.assertIn('accept-language', vary)
         headers = {'Accept-Language': 'en'}
         webreq = self.web_request(headers=headers)
         self.assertIn('lang="en"', webreq.read())
+        vary = [h.lower().strip() for h in webreq.getheader('Vary').split(',')]
+        self.assertIn('accept-language', vary)
 
     def test_response_codes(self):
         with self.admin_access.client_cnx() as cnx: