Enforce Unix Socket Connection Only to PostgreSQL Database (Version: [stellar-core 21.3.1])

[alejomendoza]

I would like to propose a feature request to enforce the use of Unix socket connections for PostgreSQL in Stellar Core.

Currently, connecting to PostgreSQL over TCP/IP introduces significant externalize lag on the validator nodes, which negatively impacts node performance. It also promotes the bad practice of running a remote database rather than hosting the database locally on the same machine as the node.

Reasons to enforce Unix socket connections:

1. Reduce Externalize Lag: A direct Unix socket connection is much faster than TCP/IP, especially when the database is hosted on the same machine, which can significantly reduce externalize lag.
2. Best Practice for Node Deployment: Limiting database connections to Unix sockets ensures that developers run the database locally on the same machine as the Stellar Core node. This is a best practice for optimal node performance and security.

I believe that enforcing Unix socket connections will help developers avoid performance degradation and promote proper validator node configuration.