netdata/health/health.d/haproxy.conf

 template: haproxy_backend_server_status
       on: haproxy_hs.down
    class: Errors
     type: Web Proxy
component: HAProxy
    units: failed servers
    every: 10s
   lookup: average -10s
     crit: $this > 0
  summary: HAProxy server status
     info: Average number of failed haproxy backend servers over the last 10 seconds
       to: sysadmin

 template: haproxy_backend_status
       on: haproxy_hb.down
    class: Errors
     type: Web Proxy
component: HAProxy
    units: failed backend
    every: 10s
   lookup: average -10s
     crit: $this > 0
  summary: HAProxy backend status
     info: Average number of failed haproxy backends over the last 10 seconds
       to: sysadmin