Flume is a distributed, reliable, and available service for efficiently collecting, aggregating, and moving large amounts of log data. It has a simple and flexible architecture based on streaming data flows. It is robust and fault tolerant with tunable reliability mechanisms and many failover and recovery mechanisms. It uses a simple extensible data model that allows for online analytic application. Learn more at flume.apache.org.

This charm provides a Flume agent designed to ingest events into the shared filesystem (HDFS) of a connected Hadoop cluster. It is meant to relate to other Flume agents such as apache-flume-syslog and apache-flume-twitter.

This charm is uses the hadoob base layer and the hdfs interface to pull its dependencies and act as a client to a hadoop namenode:

You may manually deploy the recommended environment as follows:

juju deploy apache-hadoop-namenode namenode
juju deploy apache-hadoop-resourcemanager resourcemgr
juju deploy apache-hadoop-slave slave
juju deploy apache-hadoop-plugin plugin

juju add-relation namenode slave
juju add-relation resourcemgr slave
juju add-relation resourcemgr namenode
juju add-relation plugin resourcemgr
juju add-relation plugin namenode

Deploy Flume HDFS:

juju deploy apache-flume-hdfs flume-hdfs
juju add-relation flume-hdfs plugin

The deployment at this stage isn't very exciting, as the flume-hdfs service is waiting for other Flume agents to connect and send data. You'll probably want to check out apache-flume-syslog or apache-flume-twitter to provide additional functionality for this deployment.

When flume-hdfs receives data, it is stored in a /user/flume/<event_dir> HDFS subdirectory (configured by the connected Flume charm). You can quickly verify the data written to HDFS using the command line. SSH to the flume-hdfs unit, locate an event, and cat it:

juju ssh flume-hdfs/0
hdfs dfs -ls /user/flume/<event_dir>               # <-- find a date
hdfs dfs -ls /user/flume/<event_dir>/<yyyy-mm-dd>  # <-- find an event
hdfs dfs -cat /user/flume/<event_dir>/<yyyy-mm-dd>/FlumeData.<id>

This process works well for data serialized in text format (the default). For data serialized in avro format, you'll need to copy the file locally and use the dfs -text command. For example, replace the dfs -cat command from above with the following to view files stored in avro format:

hdfs dfs -copyToLocal /user/flume/<event_dir>/<yyyy-mm-dd>/FlumeData.<id> /home/ubuntu/myFile.txt
hdfs dfs -text file:///home/ubuntu/myFile.txt

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