After continued observation, we have found that we are still getting dynamic resources served from cache without regard to our Vary: X- Forwarded-Host response header. Also, cached resources do not seem to pass the Vary header (or other headers) on. This seems like Google's edge cache is broken with regard to how an HTTP proxy server is supposed to behave. Is there any way to disable it for a billing- enabled app without losing the benefits of the Cache-Control header for other downstream proxies and user-agents?
-=- On Oct 7, 12:38 pm, Mike <[email protected]> wrote: > Ikai, > > Thanks for your response. It definitely helps to have some > confirmation that our observations about theedge cacheand billing > were correct. > > Technically, the expected behavior was that the app would behave the > same before and after enabling billing, since I don't believe the > caching differences between free and billed is documented anywhere. > > After investigating the problems we were experiencing (pages initially > served for one domain in X-Forwarded-Host resulting in cache hits for > subsequent requests for the same path specifying a different X- > Forwarded-Host), I concluded that this was probably expected behavior. > We were able to solve this problem by adding "Vary: X-Forwarded-Host" > to our response headers. Now things are working normally for our app > again. > > -Mike > > -=- > > On Oct 7, 10:56 am, "Ikai Lan (Google)" <[email protected]> > wrote: > > > > > Yes, enabling billing enables edge caching for requests that use the > > cache-control header. This is a "best effort" caching and we do not > > guarantee you will get it. > > > Can you describe what the expected behavior should be? What are you trying > > to do. > > > -- > > Ikai Lan > > Developer Programs Engineer, Google App Engine > > Blogger:http://googleappengine.blogspot.com > > Reddit:http://www.reddit.com/r/appengine > > Twitter:http://twitter.com/app_engine > > > On Wed, Oct 6, 2010 at 7:46 AM, Mike <[email protected]> wrote: > > > I have an app that sits behind a reverse proxy serving requests for > > > multiple domains using the X-Forwarded-For header. This has been > > > working very well for many months. Yesterday, after enabling billing > > > for the app, I started seeing dynamic requests that were getting > > > served the wrong content (content for the wrong domain). > > > > In troubleshooting the issue, I noticed that many of the problem > > > requests are served in only a couple of milliseconds, and the logs > > > don't contain the normal logging messages that my code should produce, > > > and don't show up in appstats. I'm assuming this means that the > > > caching I've read about but never seen to work is now serving requests > > > (since the Cache-Control header is set), and is not keeping cached > > > pages separate based on the X-Forwarded-For header, but just the path. > > > > Is there any way to confirm whether this is what is happening? If so, > > > is there a way to disable this functionality (going back to the way it > > > worked before we enabled billing), without removing the Cache-Control > > > header and losing it's benefits? > > > > -Mike > > > > -=- > > > > -- > > > You received this message because you are subscribed to the Google Groups > > > "Google App Engine" group. > > > To post to this group, send email to [email protected]. > > > To unsubscribe from this group, send email to > > > [email protected]<google-appengine%2Bunsubscrib > > > [email protected]> > > > . > > > For more options, visit this group at > > >http://groups.google.com/group/google-appengine?hl=en. -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
