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Introduction

This article provides a guide on refining haproxy  logging mechanism by leveraging the `programname` property in rsyslog, coupled with the `log-tag` directive in haproxy.
This approach will create a granular logging setup, separating logs according to their originating services and specific custom tags, enhancing overall log readability.

Though the article is written concretely for logging multiple log streams from haproxy this can be successfully applied
for any other Linux service to log as many concrete log-tagged data streams as you prefer.

Scope

The guide focuses on tailoring the logging mechanisms for two haproxy  instances named `haproxy` and `haproxyssl`, utilizing the `programname` property in rsyslog and the `log-tag` directive in haproxy for precise log management.

The haproxy and haproxyssl instances are two separate systemd config file prepared instances.
haproxy instance is simple haproxy proxying tcp traffic in non-encrypted form, whether haproxyssl is a special instance
prepared to tunnel the incoming http traffic in ssl form. Both instances of haproxy runs as a separate processes on the server.

Here is the systemd configuration of haproxy systemd service file:

# cat /usr/lib/systemd/system/haproxy.service
[Unit]
Description=HAProxy Load Balancer
After=network-online.target
Wants=network-online.target

[Service]
Environment="CONFIG=/etc/haproxy/haproxy.cfg" "PIDFILE=/run/haproxy.pid"
EnvironmentFile=/etc/sysconfig/haproxy
ExecStartPre=/usr/sbin/haproxy -f $CONFIG -c -q $OPTIONS
ExecStart=/usr/sbin/haproxy -Ws -f $CONFIG -p $PIDFILE $OPTIONS
ExecReload=/usr/sbin/haproxy -f $CONFIG -c -q $OPTIONS
ExecReload=/bin/kill -USR2 $MAINPID
SuccessExitStatus=143
KillMode=mixed
Type=notify

[Install]
WantedBy=multi-user.target

As well as the systemd service configuration for haproxyssl:
 

# cat /usr/lib/systemd/system/haproxyssl.service
[Unit]
Description=HAProxy Load Balancer
After=network-online.target
Wants=network-online.target

[Service]
Environment="CONFIG=/etc/haproxy/haproxy_ssl_prod.cfg" "PIDFILE=/run/haproxy_ssl_prod.pid"
EnvironmentFile=/etc/sysconfig/haproxy
ExecStartPre=/usr/sbin/haproxyssl -f $CONFIG -c -q $OPTIONS
ExecStart=/usr/sbin/haproxyssl -Ws -f $CONFIG -p $PIDFILE $OPTIONS
ExecReload=/usr/sbin/haproxyssl -f $CONFIG -c -q $OPTIONS
ExecReload=/bin/kill -USR2 $MAINPID
SuccessExitStatus=143
KillMode=mixed
Type=notify

[Install]
WantedBy=multi-user.target

Step 1: Configuring HAProxy instances with `log-tag`
 

To distinguish between logs from two HAProxy instances, `log-tag` directive is used to add tags to logs. This tag is used to filter these logs in rsyslog.
Modify the HAProxy configuration file in `/etc/haproxy/haproxy.*.cfg`

HAProxy Instance 1 (haproxy)
 

#———————————————————————
# Global settings
#———————————————————————
global
      log          127.0.0.1 local6 debug
      log-tag      haproxy

HAProxy Instance 2 (haproxyssl)

#———————————————————————
# Global settings
#———————————————————————
global
    log          127.0.0.1 local5 debug
    log-tag      haproxyssl

Step 2: Implementing rsyslog configuration for haproxy logs
 

Next, create a new rsyslog configuration file, stored in /etc/rsyslog.d/. Ensure the new configuration file ends in `.conf`

HAProxy Instance 1 (haproxy)

Now add rsyslog rules to filters logs based on the `programname` and the custom log tag:
 

# vi /etc/rsyslog.d/55_haproxy.conf
if $programname == 'haproxy' then /var/log/haproxy.log
&stop

HAProxy Instance 2 (haproxyssl)
# vi /etc/rsyslog.d/51_haproxy_ssl.conf
if $programname == 'haproxy_ssl' then /var/log/haproxy_ssl.log
&stop

These rules filter logs that originate from haproxy  and contain the respective string haproxy   or haproxy_ssl , directing them to their respective log files. The `& stop` directive ensures that rsyslog stops processing the log once a match is found, preventing dublication.

Finally, restart both the haproxy and rsyslog services for the changes to take effect:

# systemctl restart haproxy
# systemctl restart haproxyssl
# systemctl restart rsyslog

Reading References

haproxy:   log-tag directive

rsyslog:    rsyslogd documentation

This is a guest article originally written by: Dimitar Paskalev, guest blogging with good interesting articles is always mostly welcome 

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Tags: apache mysql, configuration file, haproxy, How to, instances, logs, Modify, rsyslog, sbin, systemd, target, using

This entry was posted on Tuesday, May 23rd, 2023 at 1:33 pm and is filed under Educational, Hacks, 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.