Klogger is a simple service that listen on TCP ports and local files and uses Krackle to produce those messages to Kafka topics.

• Basic: Small code base with few dependencies and external requirements
• Efficient: Consideration placed on minimizing object instantiation to reduce effects of GC
• Configurable: Resource consumption can be configured to tune performance

• Security: Klogger is not intended to be distributed outside a trusted security administration domain--a fancy way of saying that Klogger should be deployed only to hosts intended to have direct access to produce for your Kafka topics. There is no built-in access control or authentication.

• Will Chartrand (original author)
• Dave Ariens (current maintainer)

Performing a Maven install produces both a Debian package that currently installs on Ubuntu based Linux distributions that support upstart-enabled services as well as an RPM that can be installed on distributions that support Red Hat packages.

Below is an example configuration for running a KLogger instance that receives messages for two topics (topic1, topic2) on ports 2001, 2002 respectively. It uses 200MB worth of heap and will buffer up to 150MB GB of messages for both topics (in the event Kafka cannot ack) before dropping.

Sample /opt/klogger/config/klogger-env.sh (defines runtime configuration and JVM properties)

JAVA=`which java`
BASEDIR=/opt/klogger
CONFIGDIR="$BASEDIR/config"
LOGDIR="$BASEDIR/logs"
PIDFILE="/var/run/klogger/klogger.pid"
KLOGGER_USER="kafka"
JMXPORT=9010
LOG4JPROPERTIES=$CONFIGDIR/log4j.properties
JAVA_OPTS=""
JAVA_OPTS="$JAVA_OPTS -server"
JAVA_OPTS="$JAVA_OPTS -Xms200M -Xmx200M"
JAVA_OPTS="$JAVA_OPTS -XX:+UseParNewGC -XX:+UseConcMarkSweepGC"
JAVA_OPTS="$JAVA_OPTS -XX:+UseCMSInitiatingOccupancyOnly -XX:+CMSConcurrentMTEnabled -XX:+CMSScavengeBeforeRemark"
JAVA_OPTS="$JAVA_OPTS -XX:CMSInitiatingOccupancyFraction=80"
JAVA_OPTS="$JAVA_OPTS -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintTenuringDistribution"
JAVA_OPTS="$JAVA_OPTS -Xloggc:$LOGDIR/gc.log"
JAVA_OPTS="$JAVA_OPTS -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=10 -XX:GCLogFileSize=10M"
JAVA_OPTS="$JAVA_OPTS -Djava.awt.headless=true"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.authenticate=false"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.ssl=false"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.port=$JMXPORT"
JAVA_OPTS="$JAVA_OPTS -Dlog4j.configuration=file:$LOG4JPROPERTIES"

CLASSPATH="$CONFIGDIR:$BASEDIR/lib/*"

Sample /opt/klogger/config/klogger.properties (defines Klogger configuration, topics, and ports)

metadata.broker.list=kafka1.site.dc1:9092,kafka2.site.dc1:9092,kafka3.site.dc1:9092
compression.codec=snappy
queue.enqueue.timeout.ms=0
use.shared.buffers=true
kafka.rotate=true
num.buffers=150
#This should be a unique character/string per klogger host.
kafka.key="
source.topic1.port=2001
source.topic2.port=2002

Sample /opt/klogger/config/log4j.properties (logging)

klogger.logs.dir=/var/log/klogger
log4j.rootLogger=INFO, kloggerAppender

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=[%d] %p %m (%c)n

log4j.appender.kloggerAppender=org.apache.log4j.RollingFileAppender
log4j.appender.kloggerAppender.maxFileSize=20MB
log4j.appender.kloggerAppender.maxBackupIndex=5
log4j.appender.kloggerAppender.layout=org.apache.log4j.PatternLayout
log4j.appender.kloggerAppender.layout.ConversionPattern=%5p [%t] %d{ISO8601} %m%n
log4j.appender.kloggerAppender.File=${klogger.logs.dir}/server.log

The following additional properties apply to any configured TCP port source:

The following additional properties apply to file based sources. Note: that some of these can be defined as a globla default and optionally overwritten on a per topic basis via pre-prending a literal "source" followed by dot, then the topic name.

Whenever file.position.persist.ms time elapses or file.position.persist.lines have been read, the timer/counters are reset. Which ever event occurs first will dictate when positions are cached and then each are reset.

KLogger has full support for both regular files and FIFO files however only regular files support caching positions. Disregard mention of cached position for non-regular file types through this documentation.

Files can be non-existent, moved, deleted/created, and truncated. Here's how KLogger will handle these events accordingly:

If a file does not exist then KLogger will watch the parent directory for a creation event. Once it's created it will prepare the source accordingly and start reading from the cached position (regular files only). KLogger will just resume reading from FIFO's non-regular files without any consideration of the cached position in the event the file was previously of a different type.

When a file is deleted or moved KLogger stops reading from it and persists the position in the cache and enters into the watching state for non-existent files.

If a file being read is truncated or emptied then KLogger resets it's reader to the size of the file, persists the new position and continues reading.

If a previously non-existent file is created KLogger will instantly start reading from it, resetting any position found in the cache to zero.

Please note that KLogger uses Krackle to produce messages to Kafka, so the Krackle properties are defined in the your KLogger configuration. Please see the Krackle project for a list of it's available properties

After configuration simply start the service 'klogger start' (on Ubuntu/upstart) or 'service klogger start' (on RPM/SysV init). The Debian package also creates a symbolic from /lib/init/upstart-job to /etc/init.d/klogger so existing 'service' configurations are respected.

Exposed via Coda Hale's Metric's are:

Klogger:

• Meter: bytesReceived
• Meter: bytesReceivedTotal

Krackle:

• Meter: received
• Meter: receivedTotal
• Meter: sent
• Meter: sentTotal
• Meter: doppedQueueFull
• Meter: doppedQueueFullTotal
• Meter: doppedSendFail
• Meter: droppedSendFailTotal

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