Enhancement: Helm Chart Hooks for PostgreSQL pg_dump

[artntek]

Issue #1748 introduced the ability to manually pg_dump and automatically pg_restore backups across PostgreSQL major version upgrades.

This seems to work OK, but requires manual intervention that could be avoided by automating through the use of Helm Chart Hooks. See this example in dataone-indexer Issue 202.

Through the use of hooks, it should be possible to do a pg_dump (to provide a temporary backup) at every helm uninstall/upgrade (provided it doesn't take too long - a Values flag can be used to disable).

(Moving the pg_restore operation from its current location (an initContainer in the Metacat pod) to a helm hook would be a "nice to have", for separation of concerns. However, this may not be feasible, since pg_restore requires PostgreSQL to be running - so we'd need ot investigate the chart/hook lifecycle a bit more.)