We are supposed to update zuul/nodepool when the relevant secrets
are updated. We do that by subscribing to changes on all secrets
in the system, then check to see if they are ones that we're watching
and if so, run the appropriate operator methods.
We only updated the list of secrets to watch on startup, which means
that from a clean start where a zuul was added, we would not add
the new secrets to our list. This change updates the list after every
time that the zuul resource is created or updated.
Change-Id: Ib6191367eb2596eba560b9c570140f33866c005f
900528164e