Log

This is the optional configuration section for structured event logs. It cannot be reloaded. If present, the root value described below must appear in the main configuration file.

Root Value

The root value may be a simple string naming the log driver, for example:

  • discard

    Drop all logs. This is the default.

  • journal

    Send logs directly to journald.

  • syslog

    Send logs directly to syslog.

  • stdout

    Write logs to standard output.

    Added in version 0.3.5.

In this form, the selected driver becomes the default configuration for all loggers.

The root value may also be a map with the following keys:

  • default

    optional, type: log config

    Set the default log configuration for loggers without an explicit override.

    default: discard

  • syslog

    optional, type: syslog

    Define the reusable syslog driver configuration.

    default: not set

    Added in version 0.3.7.

  • fluentd

    optional, type: fluentd

    Define the reusable fluentd driver configuration.

    default: not set

    Added in version 0.3.7.

  • task

    optional, type: log config

    Set the log configuration for task loggers.

    default: not set

Log Config Value

Each detailed logger configuration may be a simple driver name or a map with the following keys:

  • journal

    optional, type: map

    Use the journal driver. The map is currently empty because no driver-specific keys are defined.

  • syslog

    optional, type: syslog

    Use the syslog driver.

  • fluentd

    optional, type: fluentd

    Use the fluentd driver.

  • async_channel_size

    optional, type: usize

    Set the internal async channel size.

    default: 4096

  • async_thread_number

    optional, type: usize

    Set the number of asynchronous worker threads.

    This has no effect on the discard and journal drivers.

    default: 1

  • io_error_sampling_offset

    optional, type: usize, max: 16

    I/O errors can occur while writing logs. This setting controls sampling by logging one error out of every 2^n occurrences.

    This has no effect on the discard and journal drivers.

    default: 10

Note

The discard driver has no configuration fields, so it does not have a corresponding map entry.

Drivers