Docker Image

This article explains how to use Fluentd's official Docker image, maintained by Treasure Data, Inc.

Step 0: Install Docker

Please download and install Docker from here.

Step 1: Pull Fluentd's Docker image

Then, please download Fluentd v1.6-debian-1's image by docker pull command.

$ docker pull fluent/fluentd:v1.6-debian-1

Debian and Alpine Linux version is available for Fluentd image. Debian version is recommended officially since it has jemalloc support, however Alpine image is smaller.

Step 2: Launch Fluentd Container

To make the test simple, create the example config below at /tmp/fluentd.conf. This example accepts records from http, and output to stdout.

# /tmp/fluentd.conf
@type http
port 9880
<match **>
@type stdout

Finally, you can run Fluentd with docker run command.

$ docker run -p 9880:9880 -v $(pwd)/tmp:/fluentd/etc -e FLUENTD_CONF=fluentd.conf fluent/fluentd:v1.6-debian-1
2019-08-21 00:30:37 +0000 [info]: parsing config file is succeeded path="/fluentd/etc/fluentd.conf"
2019-08-21 00:30:37 +0000 [info]: using configuration file: <ROOT>
@type http
port 9880
bind ""
<match **>
@type stdout
2019-08-21 00:30:37 +0000 [info]: starting fluentd-1.6.3 pid=6 ruby="2.6.3"
2019-08-21 00:30:37 +0000 [info]: spawn command to main: cmdline=["/usr/local/bin/ruby", "-Eascii-8bit:ascii-8bit", "/usr/local/bundle/bin/fluentd", "-c", "/fluentd/etc/fluentd.conf", "-p", "/fluentd/plugins", "--under-supervisor"]
2019-08-21 00:30:38 +0000 [info]: gem 'fluentd' version '1.6.3'
2019-08-21 00:30:38 +0000 [info]: adding match pattern="**" type="stdout"
2019-08-21 00:30:38 +0000 [info]: adding source type="http"
2019-08-21 00:30:38 +0000 [info]: #0 starting fluentd worker pid=13 ppid=6 worker=0
2019-08-21 00:30:38 +0000 [info]: #0 fluentd worker is now running worker=0
2019-08-21 00:30:38.332472611 +0000 {"worker":0,"message":"fluentd worker is now running worker=0"}

Step 3: Post Sample Logs via HTTP

Let's post sample logs via HTTP and confirm it's working. curl command is always your friend.

$ curl -X POST -d 'json={"json":"message"}' http://localhost:9880/sample.test

Use docker ps command to retrieve container ID, and use docker logs command to check the specific container's log.

$ docker ps -a
775a8e192f2b fluent/fluentd:v1.6-debian-1 "tini -- /bin/entryp…" About a minute ago Up About a minute 5140/tcp, 24224/tcp,>9880/tcp tender_leakey
$ docker logs 775a8e192f2b | tail -n 1
2019-08-21 00:33:00.570707843 +0000 sample.test: {"json":"message"}

Next Steps

Now you know how to use Fluentd via Docker. Here're a couple of Docker related documentations for Fluentd.

Also, please see the following tutorials to learn how to collect your data from various data sources.

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