How to Enable Health Checks in HAProxy

blog20210820-01.cfg

backend webservers
  server server1 192.168.50.2:80 check
  server server2 192.168.50.3:80 check
  server server3 192.168.50.4:80 check

blog20210820-02.cfg

server server1 192.168.50.2:80 check  inter 10s  fall 5  rise 5

blog20210820-03.cfg

backend webservers
  option httpchk
  server server1 192.168.50.2:80 check
  server server2 192.168.50.3:80 check
  server server3 192.168.50.4:80 check

blog20210820-04.cfg

backend webservers
  option httpchk
  http-check send meth GET  uri /health
  server server1 192.168.50.2:80 check
  server server2 192.168.50.3:80 check
  server server3 192.168.50.4:80 check

blog20210820-05.cfg

backend webservers
  option httpchk
  http-check send meth POST  uri /health  hdr Content-Type application/json  body "{ \"foo\": \"bar\" }"
  server server1 192.168.50.2:80 check
  server server2 192.168.50.3:80 check
  server server3 192.168.50.4:80 check

blog20210820-06.cfg

backend webservers
  option httpchk

  http-check connect
  http-check send meth GET uri /health
  http-check expect status 200

  http-check connect
  http-check send meth GET uri /health2
  http-check expect status 200

  server server1 192.168.50.2:80 check
  server server2 192.168.50.3:80 check
  server server3 192.168.50.4:80 check

blog20210820-07.cfg

http-check connect ssl  alpn h2,http/1.1

blog20210820-08.cfg

backend webservers
  option httpchk
  http-check send meth GET uri /health
  http-check expect status 200
  server server1 192.168.50.2:80 check
  server server2 192.168.50.3:80 check
  server server3 192.168.50.4:80 check

blog20210820-09.cfg

http-check expect string success

blog20210820-10.cfg

backend webservers
  option httpchk
  http-check send meth GET uri /health
  server server1 192.168.50.2:80 check  observe layer7  error-limit 50  on-error mark-down

blog20210820-11.cfg

backend webservers
  balance roundrobin
  server server1 192.168.50.2:80 check  weight 100  agent-check agent-inter 5s  agent-addr 192.168.50.2  agent-port 3000