haproxy.cfg

backend api
  balance roundrobin

  option httpchk GET /health
  timeout check 1000ms

  # maxconn 1 - only one concurrent connection per gunicorn
  # maxqueue 1 - only queue one request per socket before attempting other sockets
  # iter 10s - one health check every 10 seconds
  # downinter 1s - faster health checks if the socket is marked down
  # fall 5 - 5 failed health checks (50s) to remove socket
  # rise 1 - one successful health check adds socket
  default-server check maxconn 1 maxqueue 1 inter 10s downinter 1s fall 5 rise 1
  
  server gunicorn000 /var/shared/gunicorn000.sock
  server gunicorn001 /var/shared/gunicorn001.sock
  server gunicorn002 /var/shared/gunicorn002.sock
  server gunicorn003 /var/shared/gunicorn003.sock
  server gunicorn004 /var/shared/gunicorn004.sock
  server gunicorn005 /var/shared/gunicorn005.sock
  server gunicorn006 /var/shared/gunicorn006.sock
  server gunicorn007 /var/shared/gunicorn007.sock
  server gunicorn008 /var/shared/gunicorn008.sock
  server gunicorn009 /var/shared/gunicorn009.sock
  server gunicorn010 /var/shared/gunicorn010.sock
  server gunicorn011 /var/shared/gunicorn011.sock
  # and so on...