/fluentd-docker-image

Docker image for Fluentd

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Fluentd Docker Image

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Supported tags and respective Dockerfile links

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.

www.fluentd.org

Fluentd Logo

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.

debian

The image based on Debian Linux image. You may use this image when you require plugins which cannot be installed on Alpine (like fluent-plugin-systemd).

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-secure-forward. To add plugins, edit Dockerfile as following:

FROM fluent/fluentd:onbuild
WORKDIR /home/fluent
ENV PATH /home/fluent/.gem/ruby/2.3.0/bin:$PATH

# cutomize following "gem install fluent-plugin-..." line as you wish

USER root
RUN apk --no-cache add sudo build-base ruby-dev && \

    sudo -u fluent gem install fluent-plugin-elasticsearch fluent-plugin-record-reformer && \

    rm -rf /home/fluent/.gem/ruby/2.3.0/cache/*.gem && sudo -u fluent gem sources -c && \
    apk del sudo build-base ruby-dev

EXPOSE 24284

USER fluent
CMD exec fluentd -c /fluentd/etc/$FLUENTD_CONF -p /fluentd/plugins $FLUENTD_OPT

Note: This example runs apk add build-base ruby-dev 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.