pgbackrest-toggle-archiving is not idempotent

[mbanck]

AFAICT, systemctl start pgbackrest-toggle-archiving@<cluster-name> turns archiving on or off, depending on the previous state.

That makes it really difficult to handle with Ansible, as running something like

- name: Enable pgBackrest archiving
  systemd:
    name: pgbackrest-toggle-archiving@{{ postgresql_cluster }}
    state: started

Will turn archiving on or off for each run, making the Ansible runs non-idempotent.

Is there a way to circumvent that? Conceptually, running systemctl enable/disable pgbackrest-archiving@<cluster-name> would be the best from a UX perspective, but systemd won't invoke the /usr/share/elephant-shed/pgbackrest-toggle-archiving script in this case but bail out.

[mbanck]

This has been partially addressed by also providing a es_ctlcluster <cluster> enable-backup feature, which makes sure that archiving is enabled.