Swatchdog — Tail logs, match a pattern and triger actions

Note: this tutorial requires a configured SMTP server, in case you dont have consider read my article on how to configure postfix to use gmail as SMTP relay

https://medium.com/@kpatronas/ubuntu-configure-postfix-as-smtp-relay-server-using-gmail-3141a9216b83

Install swatchdog in ubuntu

sudo apt-get install swatch

Initial configuration

In this initial configuration we will create the configuration file to match patterns in file /var/log/test.log, this example can be used as a template to match your specific needs.

sudo mkdir /etc/swatchdog
sudo touch /etc/swatchdog/testlog_swatchdog_patterns.cfg
sudo touch /etc/system/systemd/swatchdog_testlog.service

Paste the following in /etc/system/systemd/swatchdog_testlog.service

[Unit]
Description=Swatchdog Service fo test.log
After=network.target
[Service]
Type=forking
User=root
ExecStart=/usr/bin/swatchdog -c /etc/swatchdog/testlog_swatchdog_patterns.cfg -t '/var/log/test.log' --daemon
[Install] WantedBy=multi-user.target

Creating our first rule

To create a rule we have to define a regex pattern that will match with appending text in file /var/log/test.log, in case of match an email alert will be sent.

paste the following in /etc/swatchdog/testlog_swatchdog_patterns.cfg , replace username@gmail.com

watchfor /test01/
exec /usr/bin/mail -s "swatchdog alert - host: ```hostname -s``` [Pattern test01 alert]" username@gmail.com

Test the rule

To test the rule you need to append ‘test01’ to /var/log/test.log

sudo echo "test01" >> /var/log/test.log

You should recieve an email alert.

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DevOps engineer, loves Linux, Python, cats and Amiga computers

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