systemd plugin for Fluentd

Overview

systemd input plugin reads logs from the systemd journal
systemd filter plugin allows for basic manipulation of systemd journal entries

Support

Join the #plugin-systemd channel on the Fluentd Slack

Requirements

fluent-plugin-systemd	fluentd	td-agent	ruby
> 0.1.0	>= 0.14.11, < 2	3	>= 2.1
0.0.x	~> 0.12.0	2	>= 1.9

The 0.x.x series is developed from this branch (master)
The 0.0.x series (compatible with fluentd v0.12, and td-agent 2) is developed on the 0.0.x branch

Installation

Simply use RubyGems:

gem install fluent-plugin-systemd -v 0.3.1

td-agent-gem install fluent-plugin-systemd -v 0.3.1

Input Plugin Configuration

<source>
  @type systemd
  tag kube-proxy
  path /var/log/journal
  filters [{ "_SYSTEMD_UNIT": "kube-proxy.service" }]
  read_from_head true
  <storage>
    @type local
    persistent true
    path kube-proxy.pos
  </storage>
  <entry>
    field_map {"MESSAGE": "log", "_PID": ["process", "pid"], "_CMDLINE": "process", "_COMM": "cmd"}
    fields_strip_underscores true
    fields_lowercase true
  </entry>
</source>

<match kube-proxy>
  @type stdout
</match>

path

Path to the systemd journal, defaults to /var/log/journal

filters

Array of filters, see here for further documentation, defaults to no filtering.

pos_file

This parameter is deprecated and will be removed in favour of storage in v1.0.

Path to pos file, stores the journald cursor. File is created if does not exist.

storage

Configuration for a storage plugin used to store the journald cursor.

Upgrading from pos_file

If pos_file is specified in addition to a storage plugin with persistent set to true, the cursor will be copied from the pos_file on startup, and the old pos_file removed.

read_from_head

If true reads all available journal from head, otherwise starts reading from tail, ignored if pos file exists (and is valid). Defaults to false.

strip_underscores

This parameter is deprecated and will be removed in favour of entry in v1.0.

If true strips underscores from the beginning of systemd field names. May be useful if outputting to kibana, as underscore prefixed fields are unindexed there.

entry

Optional configuration for an embeded systemd entry filter. See the Filter Plugin Configuration for config reference.

tag

Required

A tag that will be added to events generated by this input.

Example

For an example of a full working setup including the plugin, take a look at

Filter Plugin Configuration

<filter kube-proxy>
  @type systemd_entry
  field_map {"MESSAGE": "log", "_PID": ["process", "pid"], "_CMDLINE": "process", "_COMM": "cmd"}
  field_map_strict false
  fields_lowercase true
  fields_strip_underscores true
</filter>

field_map

Object / hash defining a mapping of source fields to destination fields. Destination fields may be existing or new user-defined fields. If multiple source fields are mapped to the same destination field, the contents of the fields will be appended to the destination field in the order defined in the mapping. A field map declaration takes the form of:

{
  "<src_field1>": "<dst_field1>",
  "<src_field2>": ["<dst_field1>", "<dst_field2>"],
  ...
}

Defaults to an empty map.

field_map_strict

If true, only destination fields from field_map are included in the result. Defaults to false.

fields_lowercase

If true, lowercase all non-mapped fields. Defaults to false.

fields_strip_underscores

If true, strip leading underscores from all non-mapped fields. Defaults to false.

Example

Given a systemd journal source entry:

{
  "_MACHINE_ID": "bb9d0a52a41243829ecd729b40ac0bce"
  "_HOSTNAME": "arch"
  "MESSAGE": "this is a log message",
  "_PID": "123"
  "_CMDLINE": "login -- root"
  "_COMM": "login"
}

The resulting entry using the above sample configuration:

{
  "machine_id": "bb9d0a52a41243829ecd729b40ac0bce"
  "hostname": "arch",
  "msg": "this is a log message",
  "pid": "123"
  "cmd": "login"
  "process": "123 login -- root"
}

Common Issues

When I look at fluentd logs, everything looks fine but no journal logs are read

This is commonly caused when the user running fluentd does not have enough permisions to read the systemd journal.

Acording to the systemd documentation:

Journal files are, by default, owned and readable by the "systemd-journal" system group but are not writable. Adding a user to this group thus enables her/him to read the journal files.

Dependencies

This plugin depends on libsystemd

Running the tests

To run the tests with docker on several distros simply run rake

For systems with systemd installed you can run the tests against your installed libsystemd with rake test

Licence

MIT

Contributions

Issues and pull requests are very welcome.

If you want to make a contribution but need some help or advice feel free to message me @errm on the Fluentd Slack, or send me an email [email protected].

We have adopted the Contributor Covenant and thus expect anyone interacting with contributors, maintainers and users of this project to abide by it.

Maintainer

Ed Robinson

Contributors

Many thanks to our fantastic contributors