How to Monitor a Whole Directory With Fluentd?

Better Stack Team
Updated on February 5, 2024

Fluentd provides an efficient way to monitor entire directories for log file updates. Let's say you want to track all log files in a directory like /var/log/app_dir, which contains multiple logs such as errors.log, success.logs, and app.log.

You can achieve this using the Fluentd in_tail plugin. Here's an example configuration:

  @type tail
  path /var/log/app_dir/*
  pos_file /var/log/fluentd/tail.pos
  tag your.log.tag

In this configuration, the tail input type is used to continuously read log events from files. The path parameter is set to /var/log/app_dir/*, where the asterisk (*) acts as a wildcard to include all files within the specified directory. The pos_file parameter is crucial as it helps Fluentd remember the last read position of each file, enabling it to resume from where it left off in case of a restart or interruption.

This setup ensures that Fluentd will monitor and read all log events from every file in the /var/log/app_dir directory as they are generated, providing comprehensive log monitoring coverage for the entire directory.

How to add multiple file paths to fluentd?

If your objective is to monitor certain files within a directory, rather than all files, Fluentd's in_tail plugin allows you to specify multiple paths for targeted log monitoring. For instance, to monitor only errors.log and app.log in the /var/log/app_dir directory, your configuration would look like this:

  @type tail
  path /var/log/app_dir/errors.log,/var/log/app_dir/app.log
  pos_file /var/log/fluentd/tail.pos
  tag your.log.tag

In this setup:

  • The tail input plugin is employed to read log events from the specified files.
  • The path property is used to list the paths of the individual files you want to monitor. These paths are separated by commas.
  • The pos_file is an essential element that enables Fluentd to track the last read position of each file. This tracking ensures Fluentd can resume reading from the correct spot after any restarts or disruptions.

When Fluentd runs with this configuration, it will read logs from both errors.log and app.log, ensuring targeted log collection.

For further insights and advanced configurations in log data management using Fluentd, consider exploring the comprehensive guide on how to collect, process, and ship log data with Fluentd.

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