Install by Ruby Gem

This article explains how to install Fluentd using Ruby gem.

Step 0: Before Installation

Please follow the Pre-installation Guide to configure your OS properly.

Step 1: Install Ruby Interpreter

Install Ruby >= 2.4 on your local environment. In addition, install ruby-dev package via Package Manager to build native extension gems.

Step 2: Install Fluentd Gem

Fetch and install the fluentd Ruby gem using gem command:

$ gem install fluentd --no-doc

The official RubyGems page is here.

Step 3: Run

Run the following commands to verify the Fluentd installation:

$ fluentd --setup ./fluent
$ fluentd -c ./fluent/fluent.conf -vv &
$ echo '{"json":"message"}' | fluent-cat debug.test

The second command starts Fluentd as a daemon. If you want to stop its daemon, you can use $ pkill -f fluentd. The last command sends Fluentd a message '{"json":"message"}' with a debug.test tag. If the installation is successful, Fluentd will output the following message:

2011-07-10 16:49:50 +0900 debug.test: {"json":"message"}

It is highly recommended to set up ntpd on the node to prevent invalid timestamps in your logs.

For large deployments, you must use jemalloc to avoid memory fragmentation. This is already included in the rpm and deb packages.

The Fluentd gem does not come with /etc/init.d/ scripts. You should use Process Management tools such as:

Next Steps

You are now ready to collect real logs with Fluentd. Refer to the following tutorials on how to collect data from various sources:

If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is an open-source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.

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