[[logging-service]]
== Logging service
Allows a plugin to provide status and diagnostic information.

NOTE: The Logging service is only available server side. 

[source,typescript]
----
import type { PluginInitializerContext, CoreSetup, Plugin, Logger } from '@kbn/core/server';

export class MyPlugin implements Plugin {
  private readonly logger: Logger;

  constructor(initializerContext: PluginInitializerContext) {
    this.logger = initializerContext.logger.get();
  }

  public setup(core: CoreSetup) {
    try {
      this.logger.debug('doing something...');
      // …
    } catch (e) {
      this.logger.error('failed doing something...');
    }
  }
}
----
=== Usage

Usage is very straightforward, one should just get a logger for a specific context and use it to log messages with
different log level.

[source,typescript]
----
const logger = kibana.logger.get('server');

logger.trace('Message with `trace` log level.');
logger.debug('Message with `debug` log level.');
logger.info('Message with `info` log level.');
logger.warn('Message with `warn` log level.');
logger.error('Message with `error` log level.');
logger.fatal('Message with `fatal` log level.');

const loggerWithNestedContext = kibana.logger.get('server', 'http');
loggerWithNestedContext.trace('Message with `trace` log level.');
loggerWithNestedContext.debug('Message with `debug` log level.');
----

And assuming logger for `server` name with `console` appender and `trace` level was used, console output will look like this:
[source,bash]
----
[2017-07-25T11:54:41.639-07:00][TRACE][server] Message with `trace` log level.
[2017-07-25T11:54:41.639-07:00][DEBUG][server] Message with `debug` log level.
[2017-07-25T11:54:41.639-07:00][INFO ][server] Message with `info` log level.
[2017-07-25T11:54:41.639-07:00][WARN ][server] Message with `warn` log level.
[2017-07-25T11:54:41.639-07:00][ERROR][server] Message with `error` log level.
[2017-07-25T11:54:41.639-07:00][FATAL][server] Message with `fatal` log level.

[2017-07-25T11:54:41.639-07:00][TRACE][server.http] Message with `trace` log level.
[2017-07-25T11:54:41.639-07:00][DEBUG][server.http] Message with `debug` log level.
----

The log will be less verbose with `warn` level for the `server` logger:
[source,bash]
----
[2017-07-25T11:54:41.639-07:00][WARN ][server] Message with `warn` log level.
[2017-07-25T11:54:41.639-07:00][ERROR][server] Message with `error` log level.
[2017-07-25T11:54:41.639-07:00][FATAL][server] Message with `fatal` log level.
----
