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Apache Chukwa User Guide

  This chapter is the detailed configuration guide to Apache Chukwa configuration.

  Please read this chapter carefully and ensure that all requirements have 
been satisfied. Failure to do so will cause you (and us) grief debugging 
strange errors and/or data loss.

  Apache Chukwa uses the same configuration system as Apache Hadoop. To configure a deploy, 
edit a file of environment variables in etc/chukwa/chukwa-env.sh -- this 
configuration is used mostly by the launcher shell scripts getting the 
cluster off the ground -- and then add configuration to an XML file to do 
things like override Apache Chukwa defaults, tell Apache Chukwa what Filesystem to use, 
or the location of the HBase configuration.

  When running in distributed mode, after you make an edit to an Apache Chukwa 
configuration, make sure you copy the content of the conf directory to all 
nodes of the cluster. Apache Chukwa will not do this for you. Use rsync.

Pre-requisites

  Apache Chukwa should work on any POSIX platform, but GNU/Linux is the only
production platform that has been tested extensively. Apache Chukwa has also been used
successfully on Mac OS X, which several members of Apache Chukwa team use for 
development.

  The only absolute software requirements are Java 1.6 or better,
Apache ZooKeeper {{${zookeeperVersion}}}, Apache HBase {{${hbaseVersion}}} and Apache Hadoop {{${hadoopVersion}}}.
  
  Apache Chukwa cluster management scripts rely on <ssh>; these scripts, however,
are not required if you have some alternate mechanism for starting and stopping
daemons.

Installing Apache Chukwa

  A minimal Apache Chukwa deployment has five components:

  * A Apache Hadoop and Apache HBase cluster on which Apache Chukwa will process data (referred to as Apache  Chukwa cluster).

  * One or more agent processes, that send monitoring data to HBase.
    The nodes with active agent processes are referred to as the monitored 
    source nodes.

  * Data analytics script, summarize Apache Hadoop Cluster Health.

  * HICC, Apache Chukwa visualization tool.

[]

[./images/chukwa_architecture.png] Apache Chukwa Components

* First Steps

  * Obtain a copy of Apache Chukwa. You can find the latest release on the 
    {{{http://hadoop.apache.org/chukwa/releases.html} Apache Chukwa release page}}.

  * Un-tar the release, via <tar xzf>.

  * Make sure a copy of Apache Chukwa is available on each node being monitored.

  * We refer to the directory containing Apache Chukwa as <CHUKWA_HOME>. It may
be helpful to set <CHUKWA_HOME> explicitly in your environment,
but Apache Chukwa does not require that you do so.

* General Configuration

  * Make sure that <JAVA_HOME> is set correctly and points to a Java 1.6 JRE. 
It's generally best to set this in <CHUKWA_HOME/etc/chukwa/chukwa-env.sh>.

  * In <CHUKWA_HOME/etc/chukwa/chukwa-env.sh>, set <CHUKWA_LOG_DIR> and
<CHUKWA_PID_DIR> to the directories where Apache Chukwa should store its
console logs and pid files.  The pid directory must not be shared between
different Apache Chukwa instances: it should be local, not NFS-mounted.

  * Optionally, set CHUKWA_IDENT_STRING. This string is
 used to name Apache Chukwa's own console log files.

Agents

  Agents are the Apache Chukwa processes that actually produce data. This section
describes how to configure and run them. More details are available in the
{{{./agent.html} Agent configuration guide}}.

* Configuration

  First, edit <$CHUKWA_HOME/etc/chukwa/chukwa-env.sh> In addition to 
the general directions given above, you should set <HADOOP_CONF_DIR> and
<HBASE_CONF_DIR>.  This should be Apache Hadoop deployment Apache Chukwa will use to 
store collected data.  You will get a version mismatch error if this is 
configured incorrectly.

  Edit the <CHUKWA_HOME/etc/chukwa/initial_adaptors> configuration file. 
This is where you tell Apache Chukwa what log files to monitor. See
{{{./agent.html#Adaptors} the adaptor configuration guide}} for
a list of available adaptors.

  There are a number of optional settings in 
<$CHUKWA_HOME/etc/chukwa/chukwa-agent-conf.xml>:

  * The most important of these is the cluster/group name that identifies the
monitored source nodes. This value is stored in each Chunk of collected data;
you can therefore use it to distinguish data coming from different groups of 
machines.

---
  <property>
    <name>chukwaAgent.tags</name>
    <value>cluster="demo"</value>
    <description>The cluster's name for this agent</description>
  </property>
---

  * Another important option is <chukwaAgent.checkpoint.dir>.
This is the directory Apache Chukwa will use for its periodic checkpoints of 
running adaptors.  It <<must not>> be a shared directory; use a local, 
not NFS-mount, directory.

  * Setting the option <chukwaAgent.control.remote> will disallow remote 
connections to the agent control socket.

** Use HBase For Data Storage

  * Configuring the pipeline: set HBaseWriter as your writer, or add it 
    to the pipeline if you are using 

---
  <property>
    <name>chukwa.agent.connector</name>
    <value>org.apache.hadoop.chukwa.datacollection.connector.PipelineConnector</value>
  </property>

  <property>
    <name>chukwa.pipeline</name>
    <value>org.apache.hadoop.chukwa.datacollection.writer.hbase.HBaseWriter</value>
  </property>
---

** Use HDFS For Data Storage

  The one mandatory configuration parameter is <writer.hdfs.filesystem>.
This should be set to the HDFS root URL on which Apache Chukwa will store data.
Various optional configuration options are described in 
{{{./pipeline.html} the pipeline configuration guide}}.

* Starting, Stopping, And Monitoring

  To run an agent process on a single node, use:

---
  sbin/chukwa-daemon.sh start agent
---

  Typically, agents run as daemons. The script <bin/start-agents.sh> 
will ssh to each machine listed in <etc/chukwa/agents> and start an agent,
running in the background. The script <bin/stop-agents.sh> 
does the reverse.

  You can, of course, use any other daemon-management system you like. 
For instance, <tools/init.d> includes init scripts for running
Apache Chukwa agents.

  To check if an agent is working properly, you can telnet to the control
port (9093 by default) and hit "enter". You will get a status message if
the agent is running normally.

Configuring Apache Hadoop For Monitoring

  One of the key goals for Apache Chukwa is to collect logs from Apache Hadoop clusters. 
This section describes how to configure Apache Hadoop to send its logs to Apache Chukwa. 
Note that these directions require Apache Hadoop 0.205.0+.  Earlier versions of 
Apache Hadoop do not have the hooks that Apache Chukwa requires in order to grab 
MapReduce job logs.

  Apache  Hadoop configuration files are located in <HADOOP_HOME/etc/hadoop>.
To setup Apache Chukwa to collect logs from Apache Hadoop, you need to change some of 
Apache Hadoop configuration files.

  * Copy CHUKWA_HOME/etc/chukwa/hadoop-log4j.properties file to HADOOP_CONF_DIR/log4j.properties

  * Copy CHUKWA_HOME/etc/chukwa/hadoop-metrics2.properties file to HADOOP_CONF_DIR/hadoop-metrics2.properties

  * Edit HADOOP_HOME/etc/hadoop/hadoop-metrics2.properties file and change $CHUKWA_LOG_DIR to your actual CHUKWA log dirctory (ie, CHUKWA_HOME/var/log)

Setup HBase Table

  Apache Chukwa is moving towards a model of using HBase to store metrics data to 
allow real-time charting. This section describes how to configure HBase and 
HICC to work together.

  * Presently, we support HBase 0.96+. If you have older HBase jars anywhere, 
they will cause linkage errors.  Check for and remove them.

  * Setting up tables:

---
  hbase/bin/hbase shell < etc/chukwa/hbase.schema
---

HICC

* Configuration

  Edit <etc/chukwa/auth.conf> and add authorized user to the list.

* Starting, Stopping, And Monitoring

  Hadoop Infrastructure Care Center (HICC) is Apache Chukwa web user interface.
HICC is started by invoking

---
  sbin/chukwa-daemon.sh start hicc
---

  Once the webcontainer with HICC has been started, point your favorite 
browser to:

---
  http://<server>:4080/hicc
---

Troubleshooting Tips

* UNIX Processes For Apache Chukwa Data Processes

  Apache Chukwa Data Processors are identified by:

---
  org.apache.hadoop.chukwa.datacollection.agent.ChukwaAgent
  org.apache.hadoop.chukwa.hicc.HiccWebServer
---

  The processes are scheduled execution, therefore they are not always 
visible from the process list.

* Emergency Shutdown Procedure

  If the system is not functioning properly and you cannot find an answer in 
the Administration Guide, execute the kill command.  The current state of 
the java process will be written to the log files. You can analyze 
these files to determine the cause of the problem.

---
kill -3 <pid>
---