dovecot - Oct 2021 - health check passthrough not 100% in combination with haproxy

I have been trying to get a simple health check in haproxy to work. But somehome
the haproxy request is differently handled then a curl request, which generates
a socket error in haproxy.

The health script echos these lines, with this config[2]

    echo -ne "HTTP/1.1 200 OK\r\n"
    echo -ne "Content-Length: 0\r\n"
    echo -ne "\r\n"
    exit 0

The curl request generates ok, haproxy generates socket error. The haproxy=yes,
reuseport=yes do not seem to resolve anything. If stop dovecot and run
"dovecot-health-check.sh | nc -l 192.168.10.46 5001" then the haproxy
check is ok. So I guess the script is ok. But what is dovecot then doing with
it's output when haproxy is requesting it?



[1]
https://discourse.haproxy.org/t/httpck-on-bash-script-results-in-socket-error/5647/16

[2]
service health-check {
  executable = script -p /usr/local/sbin/dovecot-health-check.sh
  inet_listener health-check {
    port = 5001
    haproxy = no
    reuse_port = no
 }
}

* Marc, 17.10.21 01:15
> I have been trying to get a simple health check in haproxy to work. But
somehome the haproxy request is differently handled then a curl request, which
generates a socket error in haproxy.
> [...]
For stats, you can use "socat" to talk to haproxy's stat socket
instead of using
its HTTP interface. For example, with "stats socket
/var/lib/haproxy/stats" in
haproxy's config, you can then do:

echo "show stat" | socat -
"UNIX-CONNECT:/var/lib/haproxy/stats"

Maybe there is a way to also expose your health check status on a local socket
instead of an HTTP listener? This would at least eliminate having to deal with
missing or superfluous CR/LFs, spaces, etc.

Just a thought.

HTH,
Thomas

Should this be filed as a bug somewhere?

> 
> I have been trying to get a simple health check in haproxy to work. But
> somehome the haproxy request is differently handled then a curl request,
> which generates a socket error in haproxy.
> 
> The health script echos these lines, with this config[2]
> 
>     echo -ne "HTTP/1.1 200 OK\r\n"
>     echo -ne "Content-Length: 0\r\n"
>     echo -ne "\r\n"
>     exit 0
> 
> The curl request generates ok, haproxy generates socket error. The
> haproxy=yes, reuseport=yes do not seem to resolve anything. If stop
> dovecot and run "dovecot-health-check.sh | nc -l 192.168.10.46
5001"
> then the haproxy check is ok. So I guess the script is ok. But what is
> dovecot then doing with it's output when haproxy is requesting it?
> 
> 
> 
> [1]
> https://discourse.haproxy.org/t/httpck-on-bash-script-results-in-socket-
> error/5647/16
> 
> [2]
> service health-check {
>   executable = script -p /usr/local/sbin/dovecot-health-check.sh
>   inet_listener health-check {
>     port = 5001
>     haproxy = no
>     reuse_port = no
>  }
> }