Problem

When ProxySQL is deployed behind a network load balancer, setting mysql-use_tcp_keepalive or pgsql-use_tcp_keepalive to false can cause connection issues. Load balancers may drop idle connections.

Proposed Solution

Add a warning in the error log when ProxySQL detects that either:

• mysql-use_tcp_keepalive=false
• pgsql-use_tcp_keepalive=false

Warning Message

WARNING: mysql-use_tcp_keepalive is set to false. This may cause connection drops when ProxySQL is behind a network load balancer. Consider setting this to true.

Implementation Considerations

• The warning should be logged during startup/configuration reload
• Only warn when the setting is explicitly set to false
• This is a warning, not an error - the configuration should still be allowed

Risk Level

Medium - Connection drops can cause service interruptions, but this is configuration-dependent rather than a bug.

Use Case

Helps users avoid hard-to-diagnose connectivity issues when ProxySQL is deployed in common load-balanced architectures.