haproxy.cfg

# Specifies TCP timeout on connect for use by the frontend ft_redis
# Set the max time to wait for a connection attempt to a server to succeed 
# The server and client side expected to acknowledge or send data.
defaults REDIS
mode tcp
timeout connect 3s
timeout server 6s
timeout client 6s

# Specifies listening socket for accepting client connections using the default 
# REDIS TCP timeout and backend bk_redis TCP health check.
frontend ft_redis
bind *:6378 name redis
default_backend bk_redis

# Specifies the backend Redis proxy server TCP health settings 
# Ensure it only forward incoming connections to reach a master.
backend bk_redis
option tcp-check
tcp-check connect
tcp-check send PING\r\n
tcp-check expect string +PONG
tcp-check send info\ replication\r\n
tcp-check expect string role:master
tcp-check send QUIT\r\n
tcp-check expect string +OK
server redis_a redis-a:6379 check inter 1s
server redis_b redis-b:6379 check inter 1s 
server redis_c redis-c:6379 check inter 1s