This release switches from the bitnami image to the official discourse/discourse
image. Some env vars need to be renamed for this migration; everything else
should happen automatically.

Rename these in your app's .env (the values carry over):

  DISCOURSE_SMTP_HOST     --> DISCOURSE_SMTP_ADDRESS
  DISCOURSE_SMTP_USER     --> DISCOURSE_SMTP_USER_NAME
  DISCOURSE_SMTP_AUTH     --> DISCOURSE_SMTP_AUTHENTICATION
  DISCOURSE_SMTP_PROTOCOL --> DISCOURSE_SMTP_ENABLE_START_TLS (takes a boolean true/false, not the old tls/ssl value, so translate it rather than copying it straight across)

The database now runs the discourse/postgres image, which upgrades your existing
postgres cluster to a new major version in place on first boot (no dump/restore).

That upgrade runs as the cluster's bootstrap superuser ("install user"), which the
recipe sets via POSTGRES_USER, defaulting to `postgres`. This default is correct
for clusters created by this recipe and the old bitnami recipe, so most operators
need to do nothing. ONLY if your cluster was bootstrapped with a different
superuser (e.g. `discourse`) must you set POSTGRES_USER in your app's .env before
upgrading -- otherwise pg_upgrade aborts with an install-user mismatch.