When ActiveStorage::Record uses `connects_to` for read replica support,
it creates a separate connection pool from ApplicationRecord. This causes
`after_commit` callbacks to fire in non-deterministic order - the
Attachment's `create_variants` callback can fire before the User model's
upload callback completes, resulting in FileNotFoundError.
The fix removes replica connection configuration from ActiveStorage::Record
so it shares the same connection pool as application models, ensuring
proper callback ordering.
Also reverts test workarounds that were added to work around this issue,
since the root cause is now fixed.
See: https://github.com/rails/rails/issues/53694
This adds an initial configuration for staging. Note that we are doing
this ahead of having the full infrastructure in all 3 DCs. So this
this will result in some cross-DC writes for now (e.g. we have a single cache in
IAD). We'll correct this as the infrastructure becomes available.
We'll also run jobs on every app server, until we split them out to
separate instances.
Jeremy Daer