Fuseki Logging

Fuseki logs operation details and also provides a standard NCSA request log.

Logging is via slj4j over Apache Log4J. Logging output is controlled via log4j.

Server Logs¶

NCSA request Log.¶

This log is in NCSA extended/combined log format.
Many web log analysers can process this format.

This log is normally off.

When run as a WAR file inside a webapp container (e.g. Apache Tomcat), the webapp container or reverse proxy will log access requests anyway.

Setting logging¶

The Fuseki engine looks for the log4j configuration as follows:

• Use system property log4j.configuration if defined (as usual for log4j).
• Use file:log4j.properties (current directory) if it exists
• Use file log4j.properties is the directory defined by FUSEKI_BASE
• Use java resource log4j.properties on the classpath.
• Use java resource org/apache/jena/fuseki/log4j.properties on the classpath.
• Use a built-in configuration.

The last step is a fallback to catch the case where Fuseki has been repackaged into a new WAR file and org/apache/jena/fuseki/log4j.properties omitted, or run from the base jar. It is better to include org/apache/jena/fuseki/log4j.properties.

The preferred customization is to use a custom log4j.properties file in FUSEKI_BASE. For the WAR file, FUSEKI_BASE defaults to /etc/fuseki on Linux. For the standalone server, FUSEKI_BASE defaults to directory run/ within the directory where the server is run.

Default setting¶

The default log4j.properties.

Logrotate¶

Below is an example logrotate(1) configuration (to go in /etc/logrotate.d) assuming the log file has been put in /etc/fuseki/logs/fuseki.log.

It rotates the logs once a month, compresses logs on rotation and keeps them for 6 months.

It uses copytruncate. This may lead to at most one broken log file line.

/etc/fuseki/logs/fuseki.log
{
    compress
    monthly
    rotate 6
    create
    missingok
    copytruncate
    # Date in extension.
    dateext
    # No need
    # delaycompress
}