Comment 4 for bug 1937171

> As far as I see, even without the health monitor, API requests are retried(?).

Now I know what's going on. Without the health monitor, haproxy is not aware of the backend failures but retrying the connection (wredis: redispatches - warning) to the backends all the time thanks to "option redispatch" in haproxy.cfg.

====
defaults
    log global
    retries 3
    option redispatch
    option splice-request
    option splice-response
    option http-keep-alive
====

So the backend failure is not obvious from an API user point of view which is good. So having the health monitor on top is not must-have but still nice-to-have to manage the backend service status properly instead of retrying always including the failed backend.