> On 28 Jan 2023, at 13:40, Wietse Venema <[email protected]> wrote:
>
> Gerben Wierda:
>> Currently, every time haproxy checks if postfix is still alive,
>> e.g. on port 587, I see this in my logging:
>>
>> Jan 28 13:13:20 albus submission/smtpd[97331]: warning: haproxy read: EOF
>> Jan 28 13:13:20 albus submission/smtpd[97331]: connect from unknown[unknown]
>> Jan 28 13:13:20 albus submission/smtpd[97331]: disconnect from
>> unknown[unknown] commands=0/0
>
> That is not a valid health check, it does not even complete the
> HaProxxy protocol handshake (that's why it logs "haproxy read:
> EOF"). You only verify TCP. Postfix could be comatose and this probe
> would not notice.
Yeah, I know. The reason I need it is that postfix itself is fine (never failed
me yet), but the underlying macOS of one of my servers is flakey (and I'm not
able to migrate yet for other reasons) so what happens is that if the OS runs
out of TCP sockets (which it occasionally apparently does) it then still reacts
to ping but nothing else until it hiccups and maybe garbage collects and then
everything is fine again. So, for me, actually knowing something reacts to a
TCP link is enough.
> A proper health check verifies that a service actually responds.
True.
> You can find more with "haproxy health check script". For example,
> Postfix should reply with a "220" status within 5 seconds.
Thanks, I have been looking at how to set this up, but so far no luck with the
search engines...
My HAproxy configuration says for instance (for submission)
# Backend: mail.rna.nl.990 (postfix haproxy submssion pool)
backend mail.rna.nl.990
option log-health-checks
# health check: port990-health-monitor
mode tcp
balance roundrobin
# tuning options
timeout connect 30s
timeout check 10s
timeout server 30s
server foo-990 192.168.2.100:990 check inter 300s port 990 send-proxy
server bar-990 192.168.2.101:990 check inter 300s port 990 send-proxy
But that is the dumb check. What I need to find out now is what I have to do on
the haproxy side so it properly does a postfix health check. All the examples
on the internet I have been able to find all talk about web servers.
G
