bandsintown/fluentd repository overview

⁠docker-fluentd

Docker images for Fluentd

⁠What is Fluentd?

Fluentd is an open source data collector, which lets you unify the data collection and consumption for a better use and understanding of data.

⁠How to use this image

To create endpoint that collectc logs on your host just run:

docker run -d -p 24224:24224 -v /data:/fluentd/log fluent/fluentd

Default configurations are to:

• listen port 24224 for Fluentd forward protocol
• store logs with tag docker.** into /fluentd/log/docker.*.log (and symlink docker.log)
• store all other logs into /fluentd/log/data.*.log (and symlink data.log)

⁠Environment Variables

Environment variable below are configurable to control how to execute fluentd process:

⁠FLUENTD_CONF

This variable allows you to specify configuration file name that will be used in -c Fluentd command line option.

If you want to use your own configuration file (without any optional plugins), you can do it with this environment variable and Docker volumes (-v option of docker run).

1. Write configuration file with filename yours.conf.
2. Execute docker run with -v /path/to/dir:/fluentd/etc to share /path/to/dir/yours.conf in container, and -e FLUENTD_CONF=yours.conf to read it.

⁠FLUENTD_OPT

Use this variable to specify other Fluentd command line options, like -v or -q.

⁠Image versions

This image is based on the popular Alpine Linux project⁠, available in the alpine official image⁠. Alpine Linux is much smaller than most distribution base images (~5MB), and thus leads to much slimmer images in general.

Since v0.12.26, tags are separated into vX.Y.Z and vX.Y.Z-onbuild.

⁠stable, latest

Latest version of stable Fluentd branch (currently v0.12).

⁠edge

Latest version of edge Fluentd branch (currently v0.14).

⁠vX.Y

Latest version of vX.Y Fluentd branch.

⁠vX.Y.Z

Concrete vX.Y.Z version of Fluentd.

⁠onbuild, xxx-onbuild

This image makes building derivative images easier.
See "How to build your own image"⁠ section for more details.

⁠How to build your own image

You can build a customized image based on Fluentd's onbuild image. Customized image can include plugins and fluent.conf file.

⁠1. Create a working directory

We will use this directory to build a Docker image. Type following commands on a terminal to prepare a minimal project first:

# Create project directory.
mkdir custom-fluentd
cd custom-fluentd

# Download default fluent.conf. this file will be copied to the new image.
curl https://raw.githubusercontent.com/fluent/fluentd-docker-image/master/fluent.conf > fluent.conf

# Create plugins directory. plugins scripts put here will be copied to the new image.
mkdir plugins

# Download sample Dockerfile.
curl https://raw.githubusercontent.com/fluent/fluentd-docker-image/master/Dockerfile.sample > Dockerfile

⁠2. Customize fluent.conf

Documentation of fluent.conf is available at docs.fluentd.org⁠.

⁠3. Customize Dockerfile to install plugins (optional)

You can install Fluentd plugins⁠ using Dockerfile. Sample Dockerfile installs fluent-plugin-elasticsearch and fluent-plugin-record-reformer. To add plugins, edit Dockerfile as following:

⁠Apline version

FROM bandsintown/alpine:3.4

USER root

RUN apk add --update --virtual .build-deps \
        sudo build-base ruby-dev \

 # cutomize following instruction as you wish
 && sudo -u fluent gem install \ 
        fluent-plugin-elasticsearch \
        fluent-plugin-record-reformer \

 && sudo -u fluent gem sources --clear-all \
 && apk del .build-deps \
 && rm -rf /var/cache/apk/* \
           /home/fluent/.gem/ruby/2.3.0/cache/*.gem

USER fluent

EXPOSE 24284

⁠Note

These example run apk add to be able to install Fluentd plugins which require native extensions (they are removed immediately after plugin installation).
If you're sure that plugins don't include native extensions, you can omit it to make image build faster.

⁠4. Build image

Use docker build command to build the image. This example names the image as custom-fluentd:latest:

docker build -t custom-fluentd:latest ./

⁠5. Test it

Once the image is built, it's ready to run. Following commands run Fluentd sharing ./log directory with the host machine:

mkdir log
docker run -it --rm --name custom-docker-fluent-logger -v `pwd`/log:/fluentd/log custom-fluentd:latest

Open another terminal and type following command to inspect IP address. Fluentd is running on this IP address:

docker inspect -f '{{.NetworkSettings.IPAddress}}' custom-docker-fluent-logger

Let's try to use another docker container to send its logs to Fluentd.

docker run --log-driver=fluentd --log-opt fluentd-address=FLUENTD.ADD.RE.SS:24224 python:alpine echo Hello
# and force flush buffered logs
docker kill -s USR1 custom-docker-fluent-logger

(replace FLUENTD.ADD.RE.SS with actual IP address you inspected at the previous step)

You will see some logs sent to Fluentd.

⁠References

Docker Logging | fluentd.org⁠

Fluentd logging driver - Docker Docs⁠

⁠Issues

We can't notice comments in the DockerHub so don't use them for reporting issue or asking question.

If you have any problems with or questions about this image, please contact us through a GitHub issue⁠.