title: Logging layout: website-normal

Brooklyn uses the SLF4J logging facade, which allows use of many popular frameworks including logback, java.util.logging and log4j.

The convention for log levels is as follows:

  • ERROR and above: exceptional situations which indicate that something has unexpectedly failed or some other problem has occurred which the user is expected to attend to
  • WARN: exceptional situations which the user may which to know about but which do not necessarily indicate failure or require a response
  • INFO: a synopsis of activity, but which should not generate large volumes of events nor overwhelm a human observer
  • DEBUG and lower: detail of activity which is not normally of interest, but which might merit closer inspection under certain circumstances.

Loggers follow the package.ClassName naming standard.

The default logging is to write INFO+ messages to brooklyn.info.log, and DEBUG+ to brooklyn.debug.log. Each is a rolling log file, where the past 10 files will be kept. INFO level, and above, messages will be logged to the karaf console. Use the log: commands in the karaf client, e.g. log:tail, to read these messages.

Using Logback through OSGi Pax Logging

In the OSGi based Apache Brooklyn logging is configured from ops4j pax logging.

See: Logging - OSGi based Apache Brooklyn
https://ops4j1.jira.com/wiki/display/paxlogging/Configuration

Standard Configuration

A org.ops4j.pax.logging.cfg file is included in the etc/ directly of the Brooklyn distro; this is read by brooklyn at launch time. Changes to the logging configuration, such as new appenders or different log levels, can be made directly in this file.

Karaf logging is highly configurable. For example enable the sift appender to log to separate log files for each bundle as described here: Advanced configuration

Advanced Configuration

The default logback.xml file references a collection of other log configuration files included in the Brooklyn jars. It is necessary to understand the source structure in the [logback-includes]({{ site.brooklyn.url.git }}/logging/logback-includes) project.

For example, to change the debug log inclusions, create a folder brooklyn under conf and create a file logback-debug.xml based on the [brooklyn/logback-debug.xml]({{ site.brooklyn.url.git }}/logging/logback-includes/src/main/resources/brooklyn/logback-debug.xml) from that project.

A full explanation of logging in karaf is available here.

Log File Backup

This sub-section is a work in progress; feedback from the community is extremely welcome.

The default rolling log files can be backed up periodically, e.g. using a CRON job.

Note however that the rolling log file naming scheme will rename the historic zipped log files such that brooklyn.debug-1.log.zip is the most recent zipped log file. When the current brooklyn.debug.log is to be zipped, the previous zip file will be renamed brooklyn.debug-2.log.zip. This renaming of files can make RSYNC or backups tricky.

An option is to covert/move the file to a name that includes the last-modified timestamp. For example (on mac):

LOG_FILE=brooklyn.debug-1.log.zip
TIMESTAMP=`stat -f '%Um' $LOG_FILE`
mv $LOG_FILE /path/to/archive/brooklyn.debug-$TIMESTAMP.log.zip

Logging aggregators

Integration with systems like Logstash and Splunk is possible using standard log4j configuration. Log4j can be configured to write to syslog using the SyslogAppender which can then feed its logs to Logstash.

Logbook

The logbook offers the possibility to query and view logs in the UI. By default, logs are stored in files as per configuration in etc/org.ops4j.pax.logging.cfg. The logbook can be configured against different log aggregation sources by adding the following parameters in brooklyn.cfg:

  • plain log files

      brooklyn.logbook.logStore=org.apache.brooklyn.util.core.logbook.file.FileLogStore
  brooklyn.logbook.fileLogStore.path=/var/logs/brooklyn/brooklyn.debug.log

  • or Elasticsearch released under the Apache License, version 2.0 fork created by AWS

      brooklyn.logbook.logStore=org.apache.brooklyn.util.core.logbook.opensearch.OpenSearchLogStore
  brooklyn.logbook.openSearchLogStore.host=https://localhost:9200
  brooklyn.logbook.openSearchLogStore.index=brooklyn
  brooklyn.logbook.openSearchLogStore.user=admin
  brooklyn.logbook.openSearchLogStore.password=admin
  brooklyn.logbook.openSearchLogStore.verifySsl=false

Users with root entitlement only can query and view logs in the logbook.

Logbook UI widget can be found in About section where all logs can be viewed, as well as in App Inspector Entity view and Activity view where logs filtered by entity ID and activity ID respectively.

Elasticsearch setup

Refer to the official documentation for installation guide. Fluentd daemon can be configured to read the log files for Elasticsearch. See example of Fluentd td-agent.conf below:

<source>
 @type tail
 @id input_tail_brooklyn
 @log_level debug
 <parse>
  @type multiline
  format1 /^(?<timestamp>\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}.\d{3}) (?<taskId>\S+)?-(?<entityIds>\S+)? (?<level>\w{4} |\w{5})\W{1,4}(?<bundleId>\d{1,3}) (?<class>(?:\S\.)*\S*) \[(?<threadName>\S+)\] (?<message>.*)/
  time_format %Y-%m-%dT%H:%M:%S,%L
 </parse>
 path /var/logs/brooklyn/brooklyn.debug.log
 pos_file /var/log/td-agent/brooklyn.debug.log.pos
 tag td.apachebrokyn.debug
</source>
<match td.apachebrokyn.*>
  @type elasticsearch
  hosts https://localhost:9200
  user admin
  password admin
  ssl_verify false
  logstash_format false
  index_name brooklyn
</match>

For More Information

The following resources may be useful when configuring logging: