When Haproxy received out of memory error and exited out, the docker container is still running without quitting or restarting.
It was probably caused by inotifywait in WHILE loop in bootstrap.sh. It does not try to detect if Haproxy is up or not.
The expected behavior should be that when Haproxy errors out and exited out inside Docker container, the docker container should either exit out so that the docker container could be relaunched by systemd service, or restart Haproxy inside the container.