fluent-plugin-kubernetes, a plugin for Fluentd

Installation

gem install fluent-plugin-kubernetes

Configuration

<source>
  type tail
  path /var/lib/docker/containers/*/*-json.log
  pos_file fluentd-docker.pos
  time_format %Y-%m-%dT%H:%M:%S
  tag docker.*
  format json
  read_from_head true
</source>

<match docker.var.lib.docker.containers.*.*.log>
  type kubernetes
  container_id ${tag_parts[5]}
  tag docker.${name}
</match>

<match kubernetes>
  type stdout
</match>

Docker logs in JSON format. Log files are normally in /var/lib/docker/containers/*/*-json.log, depending on what your Docker data directory is.

Assuming following inputs are coming from a log file: 0bbc558cca13c5a92cc59f33626db0aaa2afea24742d2fbe549e3a30faf7ab09-json.log:

{
  "log": "Something happened\n",
  "stream": "stdout",
  "time": "2015-03-07T20:04:17.604503223Z"
}

Then output becomes as belows

{
  "log": "Something happened\n",
  "stream": "stdout",
  "time": "2015-03-07T20:04:17.604503223Z"
  "container_id": "0bbc558cca13c5a92cc59f33626db0aaa2afea24742d2fbe549e3a30faf7ab09",
  "container_name": "k8s_CONTAINER.2f44475a_POD.NAMESPACE.api_ae0aeb72-c44f-11e4-a274-54ee7527188d_d442134f",
  "pod": "POD",
  "pod_namespace": "NAMESPACE",
  "pod_container": "CONTAINER"
}

JSON logging

Logging requires context to be really useful. Context can either be derived from log lines from known formats, but this is error prone & requires processing power. The logging application is the best place to add context.

If you use JSON for your application logs you can add context to your logs as you go. This plugin will parse your log lines & if it sees that they are JSON it will merge it in to the top level record so your contextual logging will be nicely searchable.

Something like this:

{
  "log": "{\"context\":\"something\"}",
  "stream": "stdout",
  "time": "2015-03-07T20:04:17.604503223Z"
}

Then output becomes as belows

{
  "context": "something",
  "stream": "stdout",
  "time": "2015-03-07T20:04:17.604503223Z"
  "container_id": "0bbc558cca13c5a92cc59f33626db0aaa2afea24742d2fbe549e3a30faf7ab09",
  "container_name": "k8s_CONTAINER.2f44475a_POD.NAMESPACE.api_ae0aeb72-c44f-11e4-a274-54ee7527188d_d442134f",
  "pod": "POD",
  "pod_namespace": "NAMESPACE",
  "pod_container": "CONTAINER"
}

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request

Copyright

Copyright (c) 2015 jimmidyson