Make local backup of pg_hba.conf file before modification

[vutny]

This PR enables local backup creation of modified pg_hba.conf file by default.
The config_backup Pillar setting has been introduced to trigger backup for all modified PostgreSQL server configuration files (postgresconf and pg_hba.conf).

It's very basic and useful feature, I think. @BABILEN or @javierbertoli , could you please review this? Thank you.

[EvaSDK]

Any specific reason to choose the local copy of pg_hba to .bak instead of using the file.managed backup system like the postgresql-conf state ?

[vutny]

Yeah, there is a reason. Good question, thanks! 👍

The backup parameter works completely different in file.blockreplace and file.managed states.
The approach from file.blockreplace is naive: make the backup at the same directory and append provided backup extension to the file name.

The file.managed state processes backup argument in more complex way, see: https://docs.saltstack.com/en/latest/ref/states/backup_mode.html
This is more advanced, but not always convenient. Especially if someone else manages PostgreSQL with other tools than Salt. Also, you can configure that in a Minion config.

That's why I "emulated" the behavior of backup to be similar to postgresql-conf (file.blockreplace), but just for pg_hba.conf (file.managed) using separate file.copy state.

[EvaSDK]

Ok, I thought that file.blockreplace and file.managed were behaving the same so 👍 for consistency.

[YetAnotherMinion]

Looks like there was an indentation change with list_addresses?

[myoung34]

Likely not on purpose, should be fixed before merge, but it's just for the example. Might cause confusion however.. It's also missing the -

[vutny]

Whoops, I guess I switched context too often and started to mix things :)
Indeed, YAML (and SLS) literal style scalars should be indented exactly with two spaces. Fixed, thanks!

[vutny]

And since it is just a multi-line string which is directly used in the file.blockreplace context parameter in the same way (literal style), there should be no - list indicator.

[vutny]

@javierbertoli, could you please review this? Many thanks.

[javierbertoli]

Looks good to me. Thanks @vutny and @EvaSDK!