Openflowplugin Event Logging Using Log4j

Openflowplugin Event Logging Reviews

Openflowplugin event logger is the feature which is used to log some important events of openflowplugin into a separate file using log4j.

User should configure log4j appender configuration for openflowplugin event logger in etc/org.ops4j.pax.logging.cfg file to achieve this.

Problem Description

When many log events are available in karaf.log file, it will be difficult for user to quickly find the main events with respect to openflow southbound connection. And also, as there will be huge amount of karaf logs, there are chances of log events getting rolled out in karaf.log files. Due to which we may tend to miss some of the events related to openflowplugin.

Openflowplugin event logger feature is intended to overcome this problem by logging important events of openflowplugin into a separate file using log4j appender, so that user can quickly refer to these event logs to identify important events of openflowplugin related to connection, disconnection, reconciliation, port events, errors, failures, etc.

Use Cases

  1. By default openflowplugin event logging feature will not be enabled without any configuration changes in logging configuration file.

  2. User can configure log4j appender for openflowplugin event logger(as mentioned in the configuration section) to log the important logs of openflowplugin in a separate file at the path mentioned in configuration file.

Proposed Change

  1. A log4j logger with name OfEventLog will be created and used to log the event at the time of connection, disconnection, reconciliation, etc.

  2. By default the event logger logging level is fixed to DEBUG level. Unless there will be a appender configuration present in logging configuration file, the events will not be in enqueued for logging.

  3. The openflowplugin event logs will be having a pattern consisting of time stamp of the event, description of event followed by the datapathId of the switch for which events are related.

  4. The event logs will be moved to a separate file(data/events/openflow/openflow.log file as per the configuration mentioned in configuration section) and this can be configured to different path as per the need.

  5. The file roll over strategy is chosen as to roll events into other file if the current file reaches maximum size(10MB as per configuration) and the event logs will be overwritten if such 10 files(as per configuration) are completed.

Command Line Interface (CLI)


Other Changes

Pipeline changes


Yang changes


Configuration impact

Below log4j configuration changes should be added in etc/org.ops4j.pax.logging.cfg file for logging openflowplugin events into a separate file.

org.ops4j.pax.logging.cfg = OfEventLog
log4j2.logger.ofp.level = DEBUG
log4j2.logger.ofp.additivity = false
log4j2.logger.ofp.appenderRef.OfEventRollingFile.ref = OfEventRollingFile

log4j2.appender.ofp.type = RollingRandomAccessFile = OfEventRollingFile
log4j2.appender.ofp.fileName = \${}/events/openflow/openflow.log
log4j2.appender.ofp.filePattern = \${}/events/openflow/openflow.log.%i
log4j2.appender.ofp.append = true
log4j2.appender.ofp.layout.type = PatternLayout
log4j2.appender.ofp.layout.pattern = %d{ISO8601} | %m%n
log4j2.appender.ofp.policies.type = Policies
log4j2.appender.ofp.policies.size.type = SizeBasedTriggeringPolicy
log4j2.appender.ofp.policies.size.size = 10MB
log4j2.appender.ofp.strategy.type = DefaultRolloverStrategy
log4j2.appender.ofp.strategy.max = 10
log4j2.appender.ofp.strategy.fileIndex = min

Clustering considerations

The openflowplugin event logger will be configured in the controller and are related to log events only in that controller. This will not be affecting cluster environment in any way.

Other Infra considerations


Security considerations


Scale and Performance Impact


Targeted Release





Features to Install

included with common openflowplugin features.







Primary assignee:
Other contributors:

Work Items



This doesn’t add any new dependencies.


  1. Verifying the event logs in karaf.log file, when there is no appender configuration added in logger configuration file.

  2. Making appender configuration in logger configuration file and verifying the important events of openflowplugin in the log file specified in configuration.

Unit Tests

None added newly.

Integration Tests




Documentation Impact