fluent-plugin-kubernetes_metadata_filter, a plugin for Fluentd

Installation

gem install fluent-plugin-kubernetes_metadata_filter

Configuration

Configuration options for fluent.conf are:

• kubernetes_url - URL to the API server. Set this to retrieve further kubernetes metadata for logs from kubernetes API server
• apiVersion - API version to use (default: v1)
• ca_file - path to CA file for Kubernetes server certificate validation
• verify_ssl - validate SSL certificates (default: true)
• client_cert - path to a client cert file to authenticate to the API server
• client_key - path to a client key file to authenticate to the API server
• bearer_token_file - path to a file containing the bearer token to use for authentication
• tag_to_kubernetes_name_regexp - the regular expression used to extract kubernetes metadata (pod name, container name, namespace) from the current fluentd tag. This must used named capture groups for container_name, pod_name & namespace (default: \.(?<pod_name>[^\._]+)_(?<namespace>[^_]+)_(?<container_name>.+)-(?<docker_id>[a-z0-9]{64})\.log$</pod>))
• cache_size - size of the cache of Kubernetes metadata to reduce requests to the API server (default: 1000)
• cache_ttl - TTL in seconds of each cached element. Set to negative value to disable TTL eviction (default: 3600 - 1 hour)
• watch - set up a watch on pods on the API server for updates to metadata (default: true)
• merge_json_log - merge logs in JSON format as top level keys (default: true)
• preserve_json_log - preserve JSON logs in raw form in the log key, only used if the previous option is true (default: true)
• de_dot - replace dots in labels with configured de_dot_separator, required for ElasticSearch 2.x compatibility (default: true)
• de_dot_separator - separator to use if de_dot is enabled (default: _)
• use_journal - If false (default), messages are expected to be formatted and tagged as if read by the fluentd in_tail plugin with wildcard filename. If true, messages are expected to be formatted as if read from the systemd journal. The MESSAGE field has the full message. The CONTAINER_NAME field has the encoded k8s metadata (see below). The CONTAINER_ID_FULL field has the full container uuid. This requires docker to use the --log-driver=journald log driver.
• container_name_to_kubernetes_regexp - The regular expression used to extract the k8s metadata encoded in the journal CONTAINER_NAME field (default: '^k8s_(?<container_name>[^\.]+)\.(?<container_hash>[a-z0-9]{8})_(?<pod_name>[^_]+)_(?<namespace>[^_]+)_(?<pod_id>[^_]+)_(?<pod_randhex>[a-z0-9]{8})$')
• annotation_match - Array of regular expressions matching annotation field names. Matched annotations are added to a log record.

Reading from the JSON formatted log files with in_tail and wildcard filenames:

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

<filter kubernetes.var.lib.docker.containers.*.*.log>
  type kubernetes_metadata
</filter>

<match **>
  type stdout
</match>

Reading from the systemd journal (requires the fluentd fluent-plugin-systemd and systemd-journal plugins, and requires docker to use the --log-driver=journald log driver):

<source>
  type systemd
  path /run/log/journal
  pos_file journal.pos
  tag journal
  read_from_head true
</source>

# probably want to use something like fluent-plugin-rewrite-tag-filter to
# retag entries from k8s
<match journal>
  @type rewrite_tag_filter
  rewriterule1 CONTAINER_NAME ^k8s_ kubernetes.journal.container
  ...
</match>

<filter kubernetes.**>
  type kubernetes_metadata
  use_journal true
</filter>

<match **>
  type stdout
</match>

Example input/output

Kubernetes creates symlinks to Docker log files in /var/log/containers/*.log. Docker logs in JSON format.

Assuming following inputs are coming from a log file named /var/log/containers/fabric8-console-controller-98rqc_default_fabric8-console-container-df14e0d5ae4c07284fa636d739c8fc2e6b52bc344658de7d3f08c36a2e804115.log:

{
  "log": "2015/05/05 19:54:41 \n",
  "stream": "stderr",
  "time": "2015-05-05T19:54:41.240447294Z"
}

Then output becomes as belows

{
  "log": "2015/05/05 19:54:41 \n",
  "stream": "stderr",
  "docker": {
    "id": "df14e0d5ae4c07284fa636d739c8fc2e6b52bc344658de7d3f08c36a2e804115",
  }
  "kubernetes": {
    "host": "jimmi-redhat.localnet",
    "pod_name":"fabric8-console-controller-98rqc",
    "pod_id": "c76927af-f563-11e4-b32d-54ee7527188d",
    "container_name": "fabric8-console-container",
    "namespace_name": "default",
    "namespace_id": "23437884-8e08-4d95-850b-e94378c9b2fd",
    "labels": {
      "component": "fabric8Console"
    }
  }
}

If using journal input, from docker configured with --log-driver=journald, the input looks like the journalctl -o export format:

# The stream identification is encoded into the PRIORITY field as an
# integer: 6, or github.com/coreos/go-systemd/journal.Info, marks stdout,
# while 3, or github.com/coreos/go-systemd/journal.Err, marks stderr.
PRIORITY=6
CONTAINER_ID=b6cbb6e73c0a
CONTAINER_ID_FULL=b6cbb6e73c0ad63ab820e4baa97cdc77cec729930e38a714826764ac0491341a
CONTAINER_NAME=k8s_registry.a49f5318_docker-registry-1-hhoj0_default_ae3a9bdc-1f66-11e6-80a2-fa163e2fff3a_799e4035
MESSAGE=172.17.0.1 - - [21/May/2016:16:52:05 +0000] "GET /healthz HTTP/1.1" 200 0 "" "Go-http-client/1.1"

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Test it (GEM_HOME=vendor bundle install; GEM_HOME=vendor bundle exec rake test)
5. Push to the branch (git push origin my-new-feature)
6. Create new Pull Request

Copyright

Copyright (c) 2015 jimmidyson