Running with a user (like `matrix:matrix`) fails if Etherpad is enabled,
because `/matrix/etherpad` is owned by `matrix_etherpad_user_uid`/`matrix_etherpad_user_gid` (`5001:5001`).
The `matrix` user can't acccess the Etherpad directory for this reason
and Borgmatic fails when trying to make a backup.
There may be other things under `/matrix` which similarly use
non-`matrix:matrix` permissions.
Another workaround might have been to add `/matrix/etherpad` (and
potentially other things) to `matrix_backup_borg_location_exclude_patterns`, but:
- that means Etherpad won't be backed up - not great
- only excluding Etherpad may not be enough. There may be other files we
need to exclude as well
---
Running with `root` is still not enough though.
We need at least the `CAP_DAC_OVERRIDE` capability, or we won't be able to read the
`/etc/borgmatic.d/config.yaml` configuration file (owned by
`matrix:matrix` with `0640` permissions).
---
Additionally, it seems like the backup process tries to write to at least a few directories:
- `/root/.borgmatic`
- `/root/.ssh`
- `/root/.config`
> [Errno 30] Read-only file system: '/root/.borgmatic'
> Error while creating a backup.
> /etc/borgmatic.d/config.yaml: Error running configuration file
We either need to stop mounting the container filesystem as readonly
(remove `--read-only`) or to allow writing via a `tmpfs`.
I've gone the `tmpfs` route which seems to work.
In any case, the mounted source directories (`matrix_backup_borg_location_source_directories`)
are read-only regardless, so our actual source files are protected from unintentional changes.
Without this, it's a string and borg says:
> At 'hooks.postgresql_databases[INDEX_HERE].port': '5432' is not of type 'integer'
> /etc/borgmatic/config.yaml /etc/borgmatic.d /tmp/.config/borgmatic/config.yaml /tmp/.config/borgmatic.d: No valid configuration files found
.. and fails to do anything.
This role is usable on its own and it's not tied to Matrix, so
extracting it out into an independent role that we install via
ansible-galaxy makes sense.
This also fixes the confusion from the other day, where
`matrix_postgres_*` had to be renamed to `devture_postgres_*`
(unless it was about `matrix_postgres_backup_*`).
We now can safely say that ALL `matrix_postgres_*` variables need to be
renamed.
Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2305
