This article explains how to set up Fluentd with Graylog. Graylog is a popular log management server powered by Elasticsearch and MongoDB. You can combine Fluentd and Graylog to create a scalable log analytics pipeline.
Basic Understanding of Fluentd
Linux Server (Ubuntu 18.04 LTS was used for this guide.)
Install the dependencies with the following command:
$ sudo apt install mongodb-server openjdk-8-jre-headless uuid-runtime
Graylog requires Elasticsearch, which can be instantly launched using the following commands:
# Note that Graylog 2.4 doesn't support Elasticsearch 6.X.$ wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-5.6.13.tar.gz$ tar -xzf elasticsearch-5.6.13.tar.gz$ cd elasticsearch-5.6.13
Elasticsearch is ready. Start it with:
In this article, we will use Graylog 2.4.
$ wget https://packages.graylog2.org/repo/packages/graylog-2.4-repository_latest.deb$ sudo dpkg -i graylog-2.4-repository_latest.deb
Update the package cache and install
$ sudo apt update$ sudo apt install graylog-server
/etc/graylog/server/server.conf and configure the following parameters:
echo -n ROOT_PASSWORD | sha256sum and set the hash. Also you need to set
web_enable to true to access the web interface.
Now let's start Graylog:
$ sudo systemctl start graylog-server
Go to http://localhost:9000 and log into the web interface.
To log in, use
admin as the username and
YOUR_PASSWORD as the password (the one you have set up for
Once logged in, click on
System in the top nav. Next, click on
Inputs from the left navigation bar. (Or, simply go to http://localhost:9000/system/inputs.
Then, from the dropdown, choose
GELF UDP and click on
Launch new input, which should pop up a modal dialogue, Select the
Node and fill the
Title. Then, click
Now, Graylog2 is ready to accept messages from Fluentd over UDP. It is time to configure Fluentd.
See the download page for all the options. Here, we are using the deb package:
$ wget http://packages.treasuredata.com.s3.amazonaws.com/3/ubuntu/bionic/pool/contrib/t/td-agent/td-agent_3.2.1-0_amd64.deb$ sudo dpkg -i td-agent_3.2.1-0_amd64.deb
Then, install the
out_gelf plugin to send data to Graylog. Currently, the GELF plugin is not available on RubyGems, so we need to download the plugin file and place it in
$ wget https://raw.githubusercontent.com/emsearcy/fluent-plugin-gelf/master/lib/fluent/plugin/out_gelf.rb$ sudo mv out_gelf.rb /etc/td-agent/plugin
We also need to gem-install GELF's Ruby client:
$ sudo /usr/sbin/td-agent-gem install gelf
/etc/td-agent/td-agent.conf as follows:
<source>@type syslogtag graylog2</source><match graylog2.**>@type gelfhost 127.0.0.1port 12201<buffer>flush_interval 5s</buffer></match>
/etc/rsyslog.conf and add the following line to the file:
rsyslog and Fluentd with the following commands:
$ sudo systemctl restart rsyslog$ sudo systemctl restart td-agent
When you log back into Graylog, you should be seeing a graph like this (wait for events to flow in):
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.