Allow create-backup on non-primary even when no TLS configured

[hloeung]

Steps to reproduce

1. juju deploy postgresql --channel 14/stable
2. juju add-unit postgresql -n 2
3. `juju run $(juju status postgresql | grep '^postgresql/' | grep -v 'Primary' | head -n1 | awk '{ print $1 }' | cut -d'*' -f1) create-backup

Expected behavior

Backup successfully runs

Actual behavior

Action id 68 failed: Unit cannot perform backups as TLS is not enabled

Versions

Operating system: Ubuntu

Juju CLI: 3.6.1-ubuntu-amd64

Juju agent: 3.6.1

Charm revision: 468

Additional context

Per the docs - https://charmhub.io/postgresql/docs/h-create-backup

Tip: To avoid unnecessary service downtime, always use non-primary units for the action create-backup

However:

Keep in mind that:

When TLS is enabled, create-backup can only run on replicas (non-primary)
When TLS is not enabled, create-backup can only run in the primary unit

Why is it that when TLS is not enabled, we can't trigger the backups on the non-primary unit? This limitation means we can't try to avoid unnecessary service downtime by running backups on the non-primary per the Tip.

[syncronize-issues-to-jira]

Thank you for reporting your feedback to us!

The internal ticket has been created: https://warthogs.atlassian.net/browse/DPE-6291.

This message was autogenerated

[hloeung]

This will let us have a more consistent backup story where with our various Discourse deployments, they're only consumed and used by units within the same Juju model so TLS is not enabled. Whereas with other places where we offer the database for consumption via cross-model relations and from other Juju models, TLS is enabled.