Install from Source

This article explains how to install Fluentd from source (git repository). This is useful for developers.

Step 1: Install Ruby Interpreter

Install Ruby >= 2.1 and bundler on your local environment.

Step 2: Fetch Source Code

Fetch the source code from GitHub. The official repository is located here.

$ git clone
$ cd fluentd

The master branch is now for v1 development.

Step 3: Build and Install

Build the package with rake and install it with gem:

$ bundle install
Fetching gem metadata from
Your bundle is complete!
Use `bundle show [gemname]` to see where a bundled gem is installed.
$ bundle exec rake build
fluentd xxx built to pkg/fluentd-xxx.gem.
$ gem install pkg/fluentd-xxx.gem

Step 4: 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.


Cannot install on M1 macOS

There is a known problem in the system Ruby on M1 macOS that fluentd --setup ./fluent command in Step.4 fails with an error similar to the following.

.../kernel_require.rb:XX:in `require': dlopen(...):
missing compatible arch in ... (LoadError)

The system Ruby on macOS, which is like universal.XXX-darwinXX (you can check it by $ ruby -v) may cause this error. If you use the system Ruby, this error can be resolved by reinstalling Ruby.

As an example, you can reinstall Ruby by using Homebrew.

$ brew reinstall --build-from-source ruby

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If this article is incorrect or outdated, or omits critical information, please let us know.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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