Allow fetching of WALs using both restore_command and streaming replication

[jonjomckay]

Submission type

• Request for enhancement (RFE)

Environment

Stolon version

v0.12.0

Additional environment information if useful to understand the bug

Enhancement Description

It would be incredibly helpful to allow fetching of WALs using both the restore_command and streaming replication (primary_conninfo) for standby clusters.

Currently, Stolon only supports fetching WALs using streaming replication after the initial PITR, but PostgreSQL itself supports combining both inside the recovery.conf. It's helpful for people who already have their WALs shipped to somewhere external (e.g. using wal-e), and don't want to (or can't) duplicate those WALs on the master using replication slots.

[sgotti]

@jonjomckay I implemented this in #543 . Do you have time test that PR to see if this works correctly for you and fits your needs? (I added an integration tests that creates a standby cluster recovering only using the archived wals).

Please note that standbySettings has been renamed to standbyConfig and it accepts two sub options: standbySettings (where you can set the primary_conninfo) and archiveRecoverySettings (the same of pitr, where you can set the restore_command).

You can omit one of them (or also both ending with a cluster not syncing) so you can use only the streaming replication or the wal restore.

[jonjomckay]

Thanks @sgotti! I'm out of the country this week, but I'll make sure to test it out when I'm back in the office next week.

[sgotti]

Resolved by #543

@jonjomckay Feel free to test it and report if if works for you.