druid/docs/content/Peons.md

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Peons

Peons run a single task in a single JVM. MiddleManager is responsible for creating Peons for running tasks. Peons should rarely (if ever for testing purposes) be run on their own.

JVM Configuration

Although peons inherit the configurations of their parent middle managers, explicit child peon configs in middlemanager can be set by prefixing them with:

druid.indexer.fork.property

Additional peon configs include:

Property	Description	Default
druid.peon.mode	Choices are "local" and "remote". Setting this to local means you intend to run the peon as a standalone node (Not recommended).	remote
druid.indexer.task.baseDir	Base temporary working directory.	/tmp
druid.indexer.task.baseTaskDir	Base temporary working directory for tasks.	/tmp/persistent/tasks
druid.indexer.task.hadoopWorkingPath	Temporary working directory for Hadoop tasks.	/tmp/druid-indexing
druid.indexer.task.defaultRowFlushBoundary	Highest row count before persisting to disk. Used for indexing generating tasks.	50000
druid.indexer.task.defaultHadoopCoordinates	Hadoop version to use with HadoopIndexTasks that do not request a particular version.	org.apache.hadoop:hadoop-client:2.3.0
druid.indexer.task.chathandler.type	Choices are "noop" and "announce". Certain tasks will use service discovery to announce an HTTP endpoint that events can be posted to.	noop

If the peon is running in remote mode, there must be an overlord up and running. Running peons in remote mode require the following configurations:

Property	Description	Default
druid.peon.taskActionClient.retry.minWait	The minimum retry time to communicate with overlord.	PT1M
druid.peon.taskActionClient.retry.maxWait	The maximum retry time to communicate with overlord.	PT10M
druid.peon.taskActionClient.retry.maxRetryCount	The maximum number of retries to communicate with overlord.	10

Running

The peon should very rarely ever be run independent of the middle manager.

io.druid.cli.Main internal peon <task_file> <status_file>

The task file contains the task JSON object. The status file indicates where the task status will be output.