[Feat] Check syntax of config files before reload or restart

[bkhomuts]

Problem

At the moment, it is possible to introduce an error in the postgresql configuration files, which will remain unnoticed until PostgreSQL server restart.
As Patroni is used for high availability, it is important to prevent errors, which may potentially lead to downtime.

Description

Introduce syntax check of the configuration file at least before reloading services (or better before updating the config files). This will warn the administrator if an error in configuration has been made.

Importance

nice to have

Proposed implementation

No response

[vitabaks]

Perhaps patroni --validate-config is suitable here.

https://patroni.readthedocs.io/en/latest/patroni_configuration.html#validate-patroni-configuration

[bkhomuts]

Yes, it is useful.

Perhaps patroni --validate-config is suitable here.

https://patroni.readthedocs.io/en/latest/patroni_configuration.html#validate-patroni-configuration

And perhaps also checking the result of PostgreSQL reload, and reporting if there is an error.