How to log multiple haproxy server instance processes on single server in seperate files with rsyslog filters - ☩ Walking in Light with Christ - Faith, Computing, Diary (2025)

Lets say you want to have 2 separates instances of haproxy and log the output to separate files, how this can be achived?

In this article, i'll tell in few easy steps how to enable multiple haproxy server instances created on the same Linux server / VPS or docker container to run and log its served content in separate log files without using separate file logging handlers "local"s.
The task might be helpful for people who are involved with DevOps and has to route separate proxy traffic on same linux machine.

Lets say you have the following haproxy process instances running withseparate haproxy configs:

1. haproxy
2. haproxy_worker2
3. haproxy_worker3

List of processes on the Linux host would looks like that.

[root@linux-server rsyslog.d]# ps -ef|grep -i hap
root 1151275 1147138 0 11:58 pts/2 00:00:00 grep –color=auto -i hap
root 1835200 1 0 Jan30 ? 00:00:00 /usr/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid
haproxy 1835203 1835200 0 Jan30 ? 00:10:41 /usr/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid
root 1835216 1 0 Jan30 ? 00:00:00 /usr/sbin/haproxy_worker2 -Ws -f /etc/haproxy/haproxy_worker2.cfg -p /run/haproxy_worker2.pid
haproxy 1835219 1835216 0 Jan30 ? 00:02:46 /usr/sbin/haproxy_worker2 -Ws -f /etc/haproxy/haproxy_worker2.cfg -p /run/haproxy_worker2.pid
root 1835216 1 0 Jan30 ? 00:00:00 /usr/sbin/haproxy_worker3 -Ws -f /etc/haproxy/haproxy_worker3.cfg -p /run/haproxy_worker3.pid
haproxy 1835219 1835216 0 Jan30 ? 00:02:46 /usr/sbin/haproxy_worker3 -Ws -f /etc/haproxy/haproxy_worker3.cfg -p /run/haproxy_worker3.pid

Question is how to log the 3 haproxies passed through configured connection IP and frontend / backend outputs to separate files

/var/log/haproxy.log , /var/log/haproxy_worker2.log and /var/log/haproxy_worker3.log

To achieve the task, you will need to set-up 3 rsyslog config files name it according to your preferences and make sure no other rsyslog
file with haproxy related configuration does not mess up with the configs (e.g. is not having a config start number NUMBER_file.conf prior to the below created files.

Then create lets say 49_haproxy.conf and 50_haproxy_worker2.conf and 51_haproxy_worker3.conf

[root@linux-server rsyslog.d]# cat 48_haproxy.conf
#$ModLoad imudp
$UDPServerAddress 127.0.0.1
$UDPServerRun 514
#2022/02/02: HAProxy logs to local6, save the messages
# Template to include only the timestamp in HAProxy logs
template(name="HaproxyTimestampOnly" type="string" string="%timegenerated% %msg:::drop-last-lf%n")
local6.* /var/log/haproxy.log;HaproxyTimestampOnly
# Apply the template to HAProxy prod port mapping logs
#if $programname startswith 'haproxy[' then /var/log/haproxy.log;HaproxyTimestampOnly
& stop

[root@linux-server rsyslog.d]# cat 50_haproxy_worker2.conf
$ModLoad imudp
$UDPServerAddress 127.0.0.1
$UDPServerRun 514
# Template to include only the timestamp in HAProxy logs
template(name="HaproxyTimestampOnly" type="string" string="%timegenerated% %msg:::drop-last-lf%n")

# Apply the template to HAProxy prod port mapping logs
if $programname startswith 'haproxy_worker2' then /var/log/haproxy_worker2.log;HaproxyTimestampOnly

[root@linux-server rsyslog.d]# cat 51_haproxy_worker3.conf
$ModLoad imudp
$UDPServerAddress 127.0.0.1
$UDPServerRun 514
# Template to include only the timestamp in HAProxy logs
template(name="HaproxyTimestampOnly" type="string" string="%timegenerated% %msg:::drop-last-lf%n")

# Apply the template to HAProxy prod port mapping logs
if $programname startswith 'haproxy_worker3' then /var/log/haproxy_worker3.log;HaproxyTimestampOnly

Those rsyslog configs permissions has to be as follows:

[root@linux-server home]# ls -al /etc/rsyslog.d/48_haproxy.conf
-rw-r–r– 1 root root 488 Jan 30 12:44 /etc/rsyslog.d/48_haproxy.conf
[root@linux-server home]# ls -al /etc/rsyslog.d/50_haproxy_worker2.conf
-rw-r–r– 1 root root 379 Jan 30 12:45 /etc/rsyslog.d/50_haproxy_worker2.conf
[root@linux-server home]# ls -al /etc/rsyslog.d/51_haproxy_worker2.conf
-rw-r–r– 1 root root 379 Jan 30 12:45 /etc/rsyslog.d/51_haproxy_worker2.conf

The permissions for files to log the haproxy has to be as so:

[root@linux-server home]# ls -al /var/log/haproxy.log
-rw-r—– 1 haproxy haproxy 5014349 Feb 3 12:11 /var/log/haproxy.log
[root@linux-server home]# ls -al /var/log/haproxy_worker2.log
-rw-r—– 1 root root 728139 Feb 3 12:11 /var/log/haproxy_worker2.log
[root@linux-server home]# ls -al /var/log/haproxy_worker3.log
-rw-r—– 1 root root 728139 Feb 3 12:11 /var/log/haproxy_worker3.log

To make the changes take affect restart consequentially rsyslog first and then the 3 haproxy instances:

[root@linux-server home]# systemctl restart rsyslog
[root@linux-server home]# systemctl restart haproxy
[root@linux-server home]# systemctl restart haproxy2
[root@linux-server home]# systemctl restart haproxy3

Go on and check the logs that everything comes in from the haproxys running the same server into the separate files:

[root@linux-server home]#tail -f /var/log/haproxy.log /var/log/haproxy_worker2.log /var/log/haproxy_worker3.log
…

Hope this has helped someone out there looking to solve on how to log multiple haproxy instances on the same servers into separate files.

That's all folks. Enjoy!

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Tags: configured, haproxy, How to, root root, rsyslog, sbin, separate, server instances, template, var

This entry was posted on Monday, February 3rd, 2025 at 1:42 pm and is filed under Everyday Life, Haproxy, Linux. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.