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Monitoring API-level Logs

The advantage of having per-API log files is that it is very easy to analyze/monitor what went wrong in a particular REST API defined in WSO2 Micro Integrator by looking at the log files. The API log is an additional log file, which will contain a copy of the logs to a particular REST API.

Below are the configuration details to configure the logs of a REST API called TestAPI using log4j properties.

Open MI_HOME/conf/ file using your favorite text editor to configure log4j to log the API specific logs to a file. You can configure the logger for either INFO level logs or DEBUG level logs as follows:

Enabling log4j for an API

Follow the instructions below to enable log4j2 logs for a sample REST API (named TestAPI).

  1. Open up the file (stored in the MI_HOME/conf ) directory. 
  2. Let's define a new appender for the TestAPI API by adding the following section to the end of the file (starting in a new line).


    This configuration creates a log file named TestAPI.log in the folder MI_HOME/repository/logs folder.

    # API_APPENDER is set to be a DailyRollingFileAppender using a PatternLayout.
    appender.API_APPENDER.type = RollingFile = API_APPENDER
    appender.API_APPENDER.fileName = ${sys:carbon.home}/repository/logs/TestAPI.log
    appender.API_APPENDER.filePattern = ${sys:carbon.home}/repository/logs/wso2-ei-api-%d{MM-dd-yyyy}.log
    appender.API_APPENDER.layout.type = PatternLayout
    appender.API_APPENDER.layout.pattern = TID: [%d] %5p {%c} [%logger] - %m%ex%n
    appender.API_APPENDER.policies.type = Policies
    appender.API_APPENDER.policies.time.type = TimeBasedTriggeringPolicy
    appender.API_APPENDER.policies.time.interval = 1
    appender.API_APPENDER.policies.time.modulate = true
    appender.API_APPENDER.policies.size.type = SizeBasedTriggeringPolicy
    appender.API_APPENDER.strategy.type = DefaultRolloverStrategy
    appender.API_APPENDER.strategy.max = 20
    appender.API_APPENDER.filter.threshold.type = ThresholdFilter
    appender.API_APPENDER.filter.threshold.level = INFO
  3. Register the appender (named API_APPENDER):

  4. Define a new logger to filter out TestAPI related logs:
    logger.API_LOG.appenderRef.API_APPENDER.ref = API_APPENDER
  5. Register the API_LOG logger:

  6. Save the file.

Configuring the REST API

The log4j2 configurations in the file does not create logs for the REST API by default. Add a Log mediator to the REST API's in-sequence and configure it to log messages at INFO log level.

Dynamically changing log level

You can update the log level of the REST API in a running Micro Integrator instance by using the CLI Tool. For exmaple, to change the log level to DEBUG, execute the following command on the CLI tool:

mi log-level API_LOG DEBUG

Learn more about using the command line interface.


If you change the log4j2 configuration directly from the file (without using the CLI), the Micro Integrator needs to be restarted for the changes to become effective.