Apr 25 11:34:28 il systemd[1]: Starting HAProxy Load Balancer...
Apr 25 11:34:28 il haproxy[3411]: [WARNING] 114/113428 (3411) : parsing [/etc/haproxy/haproxy.cfg:49] : 'server app1' : could not resolve address 'basinasrv', disabling server.
Apr 25 11:34:28 il haproxy[3411]: Proxy main started.
Apr 25 11:34:28 il haproxy[3411]: Proxy app started.
Apr 25 11:34:28 il haproxy[3411]: [NOTICE] 114/113428 (3411) : New worker #1 (3412) forked
Apr 25 11:34:28 il systemd[1]: Started HAProxy Load Balancer.
...
Apr 25 11:46:21 il haproxy[3412]: 127.0.0.1:45302 [25/Apr/2019:11:46:21.946] main app/<NOSRV> 0/-1/-1/-1/0 503 212 - - SC-- 1/1/0/0/0 0/0 "CONNECT serverfault.com:443 HTTP/1.1"

defaults
    # never fail on address resolution
    default-server init-addr libc,none
    #default-server init-addr last,libc,none
    option log-health-checks
    option httplog

global
    ca-base /etc/ssl/certs
    maxconn     20000
    log         /dev-log local0 debug
    user        haproxy
    chroot      /usr/share/haproxy
    pidfile     /run/haproxy.pid
    daemon

frontend  main
    bind :3129
    mode                 http
    log                  global
    maxconn              8000
    timeout              client  30s
    default_backend             app

backend app
    log                  global
    mode        http
    reqadd      Proxy-Authorization: Basic xxxxxx
    timeout     connect 5s
    timeout     server  30s
    timeout     queue   30s
    server  app1 basinsrv:443 check ssl verify required ca-file ca-certificates.crt