An issue we have seen is where a service exists, but is not running any tasks, as when a Marathon app is suspended. This causes haproxy to have an invalid configuration.
ALERT] 253/161656 (8102) : Unable to use proxy 'xxx_backend' with wrong mode, required: http, has: tcp.
[ALERT] 253/161656 (8102) : You may want to use 'mode http'.
[ALERT] 253/161656 (8102) : Proxy 'www': unable to find required use_backend: 'xxx_backend'.
[ALERT] 253/161656 (8102) : Fatal errors found in configuration.
An issue we have seen is where a service exists, but is not running any tasks, as when a Marathon app is suspended. This causes haproxy to have an invalid configuration.