Log

This section describes event-log configuration. It is optional and cannot be reloaded. If present, the root value must be defined in the main configuration file.

The section may also be set to YAML null to leave the built-in defaults in place.

Root Value

The root value can 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 syslogd.

  • stdout

    Send logs to standard output.

    Added in version 1.9.8.

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

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

  • default

    optional, type: log config

    Default log configuration for loggers without an explicit override.

    default: discard

  • syslog

    optional, type: syslog

    Shorthand for making syslog the default logger configuration for all log categories.

    default: not set

    Added in version 1.11.0.

  • fluentd

    optional, type: fluentd

    Shorthand for making fluentd the default logger configuration for all log categories.

    default: not set

    Added in version 1.11.0.

  • task

    optional, type: log config

    Log configuration for task loggers.

    default: not set

  • escape

    optional, type: log config

    Log configuration for escape loggers.

    default: not set

  • resolve

    optional, type: log config

    Log configuration for resolve loggers.

    default: not set

  • audit

    optional, type: log config

    Log configuration for audit loggers.

    default: not set

Log Config Value

Each detailed log configuration can be either a simple driver name or a map with the following keys:

  • journal

    optional, type: map

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

  • syslog

    optional, type: syslog

    Use the syslog log driver.

  • fluentd

    optional, type: fluentd

    Use the fluentd log driver.

  • async_channel_size

    optional, type: usize

    Size of the internal async channel.

    default: 4096

  • async_thread_number

    optional, type: usize

    Number of async worker threads.

    This setting has no effect for the discard and journal drivers.

    default: 1

  • io_error_sampling_offset

    optional, type: usize, max: 16

    Loggers may encounter repeated I/O errors. This setting controls exponential sampling of those errors: an error is logged every 2^n occurrences, where n is the configured value.

    This setting has no effect for the discard and journal drivers.

    default: 10

Note

The discard driver has no configuration options, so it has no corresponding map field.

Example:

log:
  default:
    syslog:
      target_udp: 192.0.2.20:514
      format_rfc5424:
        enterprise_id: 32473
    async_channel_size: 8192
  task: stdout
  audit:
    fluentd:
      address: 127.0.0.1:24224

Drivers