HAProxy Enterprise can operate as a TCP proxy, in which TCP streams are relayed through the load balancer to a pool of backend servers. The TCP stream may carry any higher-level protocol (e.g. HTTP, FTP, SMTP). Often this mode is used when clients need to communicate with applications using a specific protocol meant only for that application, such as Redis (Redis Serialization Protocol) or MySQL database servers.
There are fewer fetch methods available to inspect raw TCP streams, but also less processing overhead.
Set TCP mode
mode directive to tcp in both the
backend sections to load balancer TCP connections.
In the following example, we load balance MySQL servers. Typically, it's best to set the load balancing algorithm to least connections when the servers may hold the connection for a variable amount of time. That algorithm sends the next client to the server with the fewest active connections.
frontend mysql mode tcp bind :3306 default_backend mysql_servers backend mysql_servers mode tcp balance leastconn server s1 192.168.0.10:3306 server s2 192.168.0.11:3306