Provide a way to use multihost connection in a PostgreSQLScaler

[a-narsudinov]

Proposal

Right now the PostgreSQL scaler uses a lib/pq library which is outdated and doesn't support a lot of features we are used to in the C version of libpq and its derivatives.

One of them and critical in my eyes is a lack of multi-host connection to highly available PostgreSQL instances.

Right now in case of failover of the master node we have to somehow inform KEDA operator that it should use another connection string/host to pull metrics. That's annoying.

One of the easiest way to fix it - just to replace lib/pq with pgx I guess.

Use-Case

I would like to have a possibility to use multi-host connection strings like this postgresql://airflow:xxxxx@host1,host2:6432/airflow?sslmode=verify-full&target_session_attrs=read-write in a PostgreSQL scaler.

Is this a feature you are interested in implementing yourself?

Yes

Anything else?

No response