Postgres backup/restore and rights + roles

[Silvio Schloeffel]

Hi,

I have to integrate a Postgres DB in one of our systems and it is the
first time I work with this dbms.
Besides the normal things the integration in the daily backup is one
step on my list.

I followed the documentation at:
https://docs.bareos.org/TasksAndConcepts/Plugins.html#plugin-postgresql-fd
and can connect.

My problem:
As I wrote, it's my first contact with postgres and at the moment I
received the message:
"used role misses privileges to read configuration data_directory value"

-> it's correct because I only created a backup user without any rights.

The documentation says:
"db_user: with this user the plugin will try to connect to the database.
this role should be granted to access all pg_settings and backup
functions in the cluster."
and the troubleshooting lists some select statements to check.
BUT:
I'm a little bit irritated how select statement are enough for a
recovery process.

My question(s):
- What are the minimum requirements rights/roles that a backup user
needs for backup and recovery?
- Other hints how to create the user as secure as possible?

The postgres documentation showed my the following predefined roles:
https://www.postgresql.org/docs/16/predefined-roles.html
but I'm not sure if I should use one of these standard roles.

Thanks for your help

Best

Silvio