/fluentd-docker-image

Docker image for Fluentd

Fluentd docker image

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This container image is to create endpoint to collect logs on your host.

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)

This image uses Alpine Linux. If you want to use Ubuntu based image, use ubuntu-base tag.

Configurable ENV variables

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

FLUENTD_CONF

It's for configuration file name, specified for -c.

If you want to use your own configuration file (without any optional plugins), you can use it over this ENV variable and -v option.

  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 options, like -v or -q.

How to build your own image

It is very easy to use this image as base image. Write your Dockerfile and configuration files, and/or your own plugin files if needed.

FROM fluent/fluentd:latest
MAINTAINER your_name <...>
USER fluent
WORKDIR /home/fluent
ENV PATH /home/fluent/.gem/ruby/2.2.0/bin:$PATH
RUN gem install fluent-plugin-secure-forward
EXPOSE 24284
CMD fluentd -c /fluentd/etc/$FLUENTD_CONF -p /fluentd/plugins $FLUENTD_OPT

Files below are automatically included in build process:

  • fluent.conf: used instead of default file
  • plugins/*: copied into /fluentd/plugins and loaded at runtime

Note: Default image removed several apk packages, build-base and ruby-dev, to keep docker image small. If you want to install the plugin which depends on native extension gems, needs to re-install these packages to build it.

Testing

docker run --log-driver=fluentd --log-opt fluentd-address=192.168.0.1:24224 IMAGE echo "Hello Fluentd"

Should produce a log-file with Hello Fluentd, depending on you fluent.conf file.

References

Docker Logging | fluentd.org

Fluentd logging driver - Docker Docs