HAProxy service delayed start after switching to Backup server

[dr1m]

Hello,
I have 2 high-availability PFsense servers with HAproxy setup. (2.5.0-RELEASE)
The issue is when the master server is going offline, then the backup server is becoming Master within a second, but the HAproxy service is not starting that fast, so I have a maximum of 59 seconds downtime, because the HAproxy service starts every minute.
If I stopped the first server on 00:00:01 , the HAproxy service will start on second server on 00:01:00, but the CARP switches to backup server within the first second.
And vice-versa: if the first server just came back online, CARP switches to from backup to master and we have downtime, because HAproxy service is not started yet.

If I enable Persistent CARP Maintenance Mode on the first server, then anyway I see the same behavior - downtime up to 59s.

The CARP Monitor option in HAproxy settings is set to CARP Virtual IP -> Monitor carp interface and only run HAproxy on the firewall which is MASTER.

So in order to make a seamless transition once the master is offline, I had to disable CARP monitor option, then HAProxy service is running on both servers all the time.

May I know, what is the downside of disabling CARP monitor option and leaving HAproxy running on both firewalls?
And why there is such a big delay between CARP switching and HAproxy service start?
Thank you.

[PiBa]

@dr1m
Running on memory here.. afaik haproxy is 'subscribed' to carp events, and as such should be able to start soon after becoming master..
https://github.com/pfsense/FreeBSD-ports/blob/084b4ad9f65198720720f84d04eeed7c441ed49c/net/pfSense-pkg-haproxy/files/usr/local/pkg/haproxy.xml#L52

dont have time to check why that might fail now.. way past bedtime already here..

As for having haproxy run on both nodes, there isn't much of a downside besides that 'healthchecks' will be fired from both haproxy instances and might increase the load of the webserver a little bit..