Buildpacks: Keeping your app up to date

[fastnsilver]

Cf-butler has reporting details in /snapshot/detail and /snapshot/detail/ai endpoints that reveals the current buildpack and version contrasting with the latest buildpack version available.

What if we had a policy that could report on the discrepancies (i.e., the opportunities to upgrade apps hanging out on older buildpack versions). We do! That's something you could build with a QueryPolicy.

What if we could take that further and auto-upgrade apps to the newer buildpack versions? Model the impl off of the change-stack ApplicationPolicy. The policy would allow for the same white-listing, though we might want to consider implementing a space white-listing filter.

Auto-upgrading could be disruptive. To mitigate, when the call for cf push is made use an alternative suffix for the app name and an alternate route. This way the original app and the new app co-exist. It's left for the app team to go back and clean-up. (They could also define a delete ApplicationPolicy).