Use Filters with Fluentd

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Use Filters with Fluentd

In this lab, you will be tasked with creating a Fluentd configuration file. This configuration will have settings that will read the `/var/log/messages` file. You will add a filter to the configuration that will use the `grep `directive to search the events from the messages file and echo to the Fluentd log those events that contain the searched-for text. You will be provided a server that has Fluentd already installed and working.

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Lab Info

Level

Intermediate

Last updated

Jul 02, 2025

Duration

30m

Challenge

Create Configuration File

Create a file called /etc/td-agent/filter-grep.conf. In this file, you will create a configuration that reads the contents of the /var/log/messages file and outputs to the Fluentd stdout.
Challenge

Add a Filter

You will add a filter to the above configuration that uses grep to search using \<regexp> with the key of message for a pattern of test. The output will be directed to the stdout for Fluentd.
Challenge

Test the Filter Is Working

Start Fluentd via td-agent and use the -c option to include the configuration file you just made.

If you test by sending messages to the /var/log/messages log, you should use the word test as part of the testing.

You should see only output that has test in the string.

The command logger may be used to test sending your message to the log.

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