Mechanism to automatically update Add-ons on Container Startup?

[bsuttor]

We are considering running all upgrade_steps automatically when a container starts. Is there a built-in mechanism or recommended approach in the plone/plone-backend image to support this?

I've looked through the repository but couldn't find anything related.

Thank you :-)

[davisagli]

Nothing that exists.

You can register a handler for the zope.processlifetime.IDatabaseOpenedWithRoot event to do this on startup.

But keep in mind that if multiple containers start at the same time, there may be a race condition where they are all trying to run the same upgrade steps. If you are using Relstorage, you could use an advisory lock in postgres to make sure that only one of them tries to do this. Or, you can let it happen and catch the ConflictError that happens when the transaction is committed.