Investigate issue with haproxy service start on system reboot

[jayaddison]

Per journalctl:

-- The job identifier is 1406.
Dec 29 08:31:55 ... haproxy[1652]: [ALERT] 362/083155 (1652) : parsing [/etc/haproxy/haproxy.cfg:71] : 'server upstream' : 
Dec 29 08:31:55 ... haproxy[1652]: [ALERT] 362/083155 (1652) : Failed to initialize server(s) addr.
Dec 29 08:31:55 ... systemd[1]: haproxy.service: Control process exited, code=exited, status=1/FAILURE
...
Dec 29 08:31:55 ... systemd[1]: haproxy.service: Start request repeated too quickly.
Dec 29 08:31:55 ... systemd[1]: haproxy.service: Failed with result 'exit-code'.
-- Subject: Unit failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- The unit haproxy.service has entered the 'failed' state with result 'exit-code'.
Dec 29 08:31:55 ... systemd[1]: Failed to start HAProxy Load Balancer.
-- Subject: A start job for unit haproxy.service has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- A start job for unit haproxy.service has finished with a failure.

This name resolution failure seems to have resulted in repeat failures to start haproxy on clean system boot, which then resulted in systemd deciding not to continue attempting to start the service.

Expected result: a fresh power on of the host should restore all application services, including haproxy.