Graylog Extended Format logging driver

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The gelf logging driver is a convenient format that is understood by a number of tools such as Graylog,Logstash, and Fluentd. Many tools use this format.

In GELF, every log message is a dict with the following fields:

version
host (who sent the message in the first place)
timestamp
short and long version of the message
any custom fields you configure yourself

Usage

To use the gelf driver as the default logging driver, set the log-driver and log-opt keys to appropriate values in the daemon.json file, which is located in /etc/docker/ on Linux hosts or C:\ProgramData\docker\config\daemon.json on Windows Server. For more about configuring Docker using daemon.json, see daemon.json.

The following example sets the log driver to gelf and sets the gelf-address option.

{
  "log-driver": "gelf",
  "log-opts": {
    "gelf-address": "udp://1.2.3.4:12201"
  }
}

Restart Docker for the changes to take effect.

To use gelf as the default logging driver for new containers, pass the --log-driver and --log-opt options to the Docker daemon:

dockerd
  -–log-driver gelf –-log-opt gelf-address=udp://1.2.3.4:12201 \

To make the configuration permanent, you can configure it in /etc/docker/daemon.json:

{
  "log-driver": "gelf",
  "log-opts":  {
    "gelf-address": "udp://1.2.3.4:12201"
  }
}

You can set the logging driver for a specific container by setting the --log-driver flag when using docker create or docker run:

$ docker run \
      -–log-driver gelf –-log-opt gelf-address=udp://1.2.3.4:12201 \
      alpine echo hello world

GELF Options

The gelf logging driver supports the following options:

Option	Description	Example value
`gelf-address`	The address of the GELF server. `udp` is the only supported URI specifier and you must specify the port.	`--log-opt gelf-address=udp://192.168.0.42:12201`
`gelf-compression-type`	The type of compression the GELF driver uses to compress each log message. Allowed values are `gzip`, `zlib` and `none`. The default is `gzip`.	`--log-opt gelf-compression-type=gzip`
`gelf-compression-level`	The level of compression when `gzip` or `zlib` is the `gelf-compression-type`. An integer in the range of `-1` to `9` (BestCompression). Default value is 1 (BestSpeed). Higher levels provide more compression at lower speed. Either `-1` or `0` disables compression.	`--log-opt gelf-compression-level=2`
`tag`	A string that is appended to the `APP-NAME` in the `gelf` message. By default, Docker uses the first 12 characters of the container ID to tag log messages. Refer to the log tag option documentation for customizing the log tag format.	`--log-opt tag=mailer`
`labels`	Applies when starting the Docker daemon. A comma-separated list of logging-related labels this daemon will accept. Adds additional key on the `extra` fields, prefixed by an underscore (`_`). Used for advanced log tag options.	`--log-opt labels=production_status,geo`
`env`	Applies when starting the Docker daemon. A comma-separated list of logging-related environment variables this daemon will accept. Adds additional key on the `extra` fields, prefixed by an underscore (`_`). Used for advanced log tag options.	`--log-opt env=os,customer`
`env-regex`	Similar to and compatible with `env`. A regular expression to match logging-related environment variables. Used for advanced log tag options.	`--log-opt env-regex=^(os \| customer).`

Examples

This example configures the container to use the GELF server running at 192.168.0.42 on port 12201.

$ docker run -dit \
             --log-driver=gelf \
             --log-opt gelf-address=udp://192.168.0.42:12201 \
             alpine sh

graylog, gelf, logging, driver