Gae Instance Is Serving On Different Url

My google app engine instance is serving on different url than the default's one. Recently I uploaded an GAE project to the newly created instance of code foo-backend. On seeing t

Solution 1:

In your app.yaml you have version: 1.

To see the 'why' of what's going on here, consider the following scenario: You have version n of your app deployed, with the front-end queuing work for the back-end. You deploy version n+1 and make it the default. But you made a coordinated change between front-ends and back-ends. What now happens if work queued by front-end version n is received by a version n+1 backend? Depending on the change, it might cause mayhem.

The only safe thing to do is to arrange for work queued by a version n front-end to be handled by a version n back-end until all version n work is drained. Meanwhile work queued by a version n+1 front-end get handled by a version n+1 backend. How does this be guaranteed? By encoding the default version at the time the work is queued in the URL.