Advanced log configuration

GeoServer uses the Log4J framework for logging, which is configured by selecting a logging profile (in the global settings).

The GeoServer logging profiles assign logging levels to specific server operations:

  • GeoServer loggers record server function and the activity of individual services.

  • GeoWebCache loggers record the activity of the tile protocol library used by GeoServer.

  • GeoTools loggers record the activity of the data access and rendering library used by GeoServer.

  • The appender stdout is setup as a Console appender sending information to standard output, based on Log to Stdout global settings.

  • The appender geoserverlogfile is setup as a FileAppender or RollingFile appender sending information to the Log location global settings.

  • Logging levels range from:

    • Failure (FATAL, ERROR, WARN) levels

    • Operational (INFO, CONFIG) levels

    • Verbose (DEBUG, TRACE, FINEST) levels

In addition to the built-in profiles you may setup a custom logging profile, or override the logging configuration completely (even to use another logging library altogether).

Custom logging profiles

Anyone can write a new logging profile by adding a Log4J configuration file to the list of files already available in the $GEOSERVER_DATA_DIR/logs folder.

Profiles in this folder that match *_LOGGING.* will be listed on the global settings page as available for use. The name of the file, excluding the extension, will be presented as the profile name.

Here is an example, taken from the DEFAULT_LOGGING.xml configuration, which enables additional GeoServer log messages to be included in the logs:

<?xml version="1.0" encoding="UTF-8"?>
<!-- This log4j configuration file needs to stay here, and is used as the default logging setup -->
<!-- during data_dir upgrades and in case the chosen logging config isn't available.            -->
<Configuration name="DEFAULT_LOGGING" status="fatal" dest="out">
    <Appenders>
        <Console name="stdout" target="SYSTEM_OUT">
            <PatternLayout pattern="%date{dd mmm HH:mm:ss} %-6level [%logger{2}] - %msg%n%throwable{filters(org.junit,org.apache.maven,sun.reflect,java.lang.reflect)}"/>
        </Console>
        <RollingFile name="geoserverlogfile">
            <filename>logs/geoserver.log</filename>
            <filePattern>logs/geoserver-%i.log</filePattern>
            <PatternLayout pattern="%date{dd mmm HH:mm:ss} %-6level [%logger{2}] - %msg%n%throwable{filters(org.junit,org.apache.maven,sun.reflect,java.lang.reflect)}"/>
            <Policies>
                <SizeBasedTriggeringPolicy size="20 MB" />
            </Policies>
            <DefaultRolloverStrategy max="3" fileIndex="min"/>
        </RollingFile>
    </Appenders>
    <Loggers>
        <Logger name="org.geotools" level="warn" additivity="false">
            <AppenderRef ref="stdout"/>
            <AppenderRef ref="geoserverlogfile"/>
        </Logger>
        <Logger name="org.geotools.factory" level="warn" additivity="false">
            <AppenderRef ref="stdout"/>
            <AppenderRef ref="geoserverlogfile"/>
        </Logger>
        <Logger name="org.geoserver" level="CONFIG" additivity="false">
            <AppenderRef ref="stdout"/>
            <AppenderRef ref="geoserverlogfile"/>
        </Logger>
        <Logger name="org.vfny.geoserver" level="CONFIG" additivity="false">
            <AppenderRef ref="stdout"/>
            <AppenderRef ref="geoserverlogfile"/>
        </Logger>

        <Logger name="org.springframework" level="warn" additivity="false">
            <AppenderRef ref="stdout"/>
            <AppenderRef ref="geoserverlogfile"/>
        </Logger>

        <Logger name="org.geowebcache" level="CONFIG" additivity="false">
            <AppenderRef ref="stdout"/>
            <AppenderRef ref="geoserverlogfile"/>
        </Logger>
        <Logger name="org.geowebcache.seed" level="warn" additivity="false">
            <AppenderRef ref="stdout"/>
            <AppenderRef ref="geoserverlogfile"/>
        </Logger>
        <Root level="warn">
            <AppenderRef ref="stdout"/>
            <AppenderRef ref="geoserverlogfile"/>
        </Root>
    </Loggers>
</Configuration>

Any custom configuration can be setup to enable specific packages to emit logs at the desired logging level.

There are however a few rules to follow:

  • Custom levels are available for CONFIG and FINEST levels.

  • Appenders are used to output logging information, with GeoServer providing external configuration for appenders named geoserverlogfile and stdout.

    • Always include a geoserverlogfile FileAppender or RollingFile appender that GeoServer will configure to work against the location configured in the global settings.

      Care is taken to preserve your file extension when updating <filename> location, so if you wish to log to access_logs.txt you may do so, and the txt extension will be preserved.

    • When setting geoserverlogfile appender as RollingFile appender, care is taken to preserve your <filePattern> extensions, which must align with the roll over strategies configured.

      As an example -%i is used with DefaultRolloverStrategy to produce a maximum of 3 backup files.

      <RollingFile name="geoserverlogfile">
          <filename>logs/geoserver.log</filename>
          <filePattern>logs/geoserver-%i.log</filePattern>
          <PatternLayout pattern="%date{dd mmm HH:mm:ss} %-6level [%logger{2}] - %msg%n%throwable{filters(org.junit,org.apache.maven,sun.reflect,java.lang.reflect)}"/>
          <Policies>
              <SizeBasedTriggeringPolicy size="20 MB" />
          </Policies>
          <DefaultRolloverStrategy max="3" fileIndex="min"/>
      </RollingFile>
      
    • a Console appender writing to the standard output should be called stdout and again GeoServer will enable/disable it according to the configuration set in the global settings

      <Console name="stdout" target="SYSTEM_OUT">
          <PatternLayout pattern="%date{dd mmm HH:mm:ss} %-6level [%logger{2}] - %msg%n%throwable{filters(org.junit,org.apache.maven,sun.reflect,java.lang.reflect)}"/>
      </Console>
      
  • Loggers are used to collect messages from geoserver components, and individual libraries used.

    • GeoServer Logger names match up with the package names in the project javadocs overview (available for download).

      As an example package org.geoserver.wms is listed, allowing level of WMS service logging to be controlled:

      <Logger name="org.geoserver.wms" level="debug" additivity="false">
          <AppenderRef ref="stdout"/>
          <AppenderRef ref="geoserverlogfile"/>
      </Logger>
      
    • GeoTools Logger names match up with the package names in the project javadocs overview.

      As an example package org.geotools.data.shapefile is listed, allowing level of shapefile logging to be controlled:

      <Logger name="org.geotools.data.shapefile" level="debug" additivity="false">
          <AppenderRef ref="stdout"/>
          <AppenderRef ref="geoserverlogfile"/>
      </Logger>
      
    • Assign a level to each logger indicating the level of detail you wish to record:

      Level

      Description

      OFF

      Turn off all logging

      FATAL

      A serious problem has occurred, application may be crashing or in need of restart

      ERROR

      Problem has occurred, application unable to perform requested operation

      WARN

      Potential problem, application will try and continue

      INFO

      Normal function indicating what application is doing.

      CONFIG

      Normal application function during application startup and configuration

      DEBUG

      Internal messages intended for debugging

      TRACE

      Metod by method tracing of execution

      FINEST

      Really detailed troubleshooting of an algorithm

      ALL

      Turn on all logging

      The more verbose logging levels potentially include a strack-trace showing where the message occurred.

    • Use additivity="false" to prevent a message collected from one logger from being passed to the next.

    If you end up with double log messages chances check for this common misconfiguration.

    • The Root logger is last in the list and should collect everything.

Example of console only logging

  1. Copy an example such as QUIET_LOGGING.xml to CONSOLE_LOGGING.xml:

  2. Update the initial part of CONSOLE_LOGGING.xml with the new name:

    <?xml version="1.0" encoding="UTF-8"?>
    <Configuration name="CONSOLE_LOGGING" status="fatal" dest="out">
    
  3. Double check the Console appender configuration:

    <Appenders>
        <Console name="stdout" target="SYSTEM_OUT">
            <PatternLayout pattern="%date{dd mmm HH:mm:ss} %-6level [%logger{2}] - %msg%n%"/>
        </Console>
    </Appenders>
    
  1. Add appenders for geoserver (and any others you wish to track):

    <Logger name="org.geoserver" level="ERROR" additivity="false">
        <AppenderRef ref="stdout"/>
    </Logger>
    <Logger name="org.vfny.geoserver" level="ERROR" additivity="false">
        <AppenderRef ref="stdout"/>
    </Logger>
    
  2. Double check the root logger:

    <Root level="FATAL">
        <AppenderRef ref="stdout"/>
    </Root>
    
  3. This result provides minimal feedback to the console, only reporting when GeoServer encounters an error.

Overriding the log location setup in the GeoServer configuration

When setting up a cluster of GeoServer machines it is common to share a single data directory among all the cluster nodes.

There is however a gotcha, all nodes would end up writing the logs in the same file, which would cause various kinds of troubles depending on the operating system file locking rules (a single server might be able to write, or all together in an uncontrolled manner resulting in an unreadable log file).

A common choice could be to use the machine name as a distinction, setting values such as logs/geoserver_node1.log, logs/geoserver_node2.log and so on: in this case all the log files would still be contained in the data directory and properly rotated, but each server would have its own separate log file to write on.

In this case it is convenient to set a separate log location for each GeoServer node:

  • The GEOSERVER_LOG_LOCATION parameter can be set as system property, environment variables, or servlet context parameters:

    GEOSERVER_LOG_LOCATION=<the location of the file>
    

    This setting overrides global setting, and is applied to geoserverlogfile appender as a template for filename and filePattern.

  • This same effect may be obtained using Log4J property substitution, where a wide range of property lookups are available.

    <RollingFile name="geoserverlogfile">
        <filename>logs/geoserver-${hostName}.log</filename>
        <filePattern>logs/geoserver-${hostName}-%d{yyyy-MM-dd-HH}-%i.zip</filePattern>
        <PatternLayout pattern="%date{dd mmm HH:mm:ss} %-6level [%logger{2}] - %msg%n"/>
        <Policies>
          <OnStartupTriggeringPolicy />
          <SizeBasedTriggeringPolicy size="20 MB" />
          <TimeBasedTriggeringPolicy />
        </Policies>
        <DefaultRolloverStrategy max="9" fileIndex="min"/>
    </RollingFile>
    

    Where ${hostName} is the current system host name or ip address.

Forcing GeoServer to relinquish Log4J control

GeoServer internally overrides the Log4J configuration by using the current logging configuration as a template and applying the log location and standard output settings configured by the administrator.

If you wish GeoServer not to override the normal Log4J behavior you can set the following parameter among the JVM system variables, environment variables, or servlet context parameters:

RELINQUISH_LOG4J_CONTROL=true

This can be combined with log4j2.configurationFile system property to configure Log4J externally :

-DRELINQUISH_LOG4J_CONTROL=true -Dlog4j2.configurationFile=logging_configuration.xml

Forcing GeoServer to use an alternate logging redirection

GeoServer uses the GeoTools logging framework, which in turn is based on Java Logging, but allowing to redirect all message to an alternate framework of users choice.

By default GeoServer setups a Log4J redirection, but it is possible to configure GeoServer to use plain Java Logging, or Commons Logging instead (support for other loggers is also possible by using some extra programming).

If you wish to force GeoServer to use a different logging mechanism set the following parameters among the JVM system variables, environment variables, or servlet context parameters:

GT2_LOGGING_REDIRECTION=[CommonsLogging,JavaLogging,Log4J,Log4J2,LogBack]
RELINQUISH_LOG4J_CONTROL=true

As noted in the example you’ll also have to demand that GeoServer does not exert control over the Log4J configuration.

Force java logging example

As an example to configure java logging:

-DRELINQUISH_LOG4J_CONTROL=true -DGT2_LOGGING_REDIRECTION=JavaLogging -Djava.util.logging.config.file=logging.properties

With java util logging configuration provided by logging.properties:

handlers=java.util.logging.ConsoleHandler

java.util.logging.ConsoleHandler.level = ALL
java.util.logging.ConsoleHandler.formatter = org.geotools.util.logging.MonolineFormatter
org.geotools.util.logging.MonolineFormatter.source = class:short

.level= ALL
org.geoserver.level = CONFIG
org.vfny.geoserver.level = WARN

org.geotools.level = WARN
org.geotools.factory.level = WARN