haproxy
TLDR
Start HAProxy
$ haproxy -f [/etc/haproxy/haproxy.cfg]
Check configuration$ haproxy -c -f [/etc/haproxy/haproxy.cfg]
Reload configuration$ haproxy -f [config.cfg] -sf $(pidof haproxy)
Start in daemon mode$ haproxy -D -f [config.cfg]
Show version$ haproxy -v
SYNOPSIS
haproxy [options] -f config
DESCRIPTION
HAProxy is a high-performance TCP/HTTP load balancer and proxy. It distributes traffic across multiple servers, providing high availability, health checking, and SSL termination.
HAProxy is widely used in production environments for its reliability, performance, and extensive feature set including ACLs, rate limiting, and detailed statistics.
PARAMETERS
-f file
Configuration file.-c
Check configuration and exit.-D
Daemon mode.-sf pids
Soft-stop old processes.-st pids
Hard-stop old processes.-p pidfile
PID file path.-n maxconn
Maximum connections.-N maxconn
Default per-proxy maxconn.-d
Debug mode.-V
Verbose mode.
CONFIG EXAMPLE
$ frontend http_front
bind *:80
default_backend http_back
backend http_back
balance roundrobin
server web1 192.168.1.1:80 check
server web2 192.168.1.2:80 check
bind *:80
default_backend http_back
backend http_back
balance roundrobin
server web1 192.168.1.1:80 check
server web2 192.168.1.2:80 check
CAVEATS
Configuration changes require reload. Complex ACLs need careful testing. Statistics require separate configuration. SSL setup needs certificate management.
HISTORY
HAProxy was created by Willy Tarreau in 2000 and has become one of the most widely deployed load balancers. It powers high-traffic sites including GitHub, Reddit, and Stack Overflow.
