Overview
The Apache Hadoop software library is a framework that allows for the distributed processing of large data sets across clusters of computers using a simple programming model.
This charm deploys an HDFS master node running the NameNode component of Apache Hadoop 2.7.1, which manages the distribution and replication of data among the various DataNode components.
Usage
This charm is intended to be deployed via one of the apache bundles. For example:
juju quickstart apache-analytics-sql
This will deploy the Apache Hadoop platform with Apache Hive available to perform SQL-like queries against your data.
You can also manually load and run map-reduce jobs via the plugin charm included in the bigdata bundles linked above:
juju scp my-job.jar plugin/0:
juju ssh plugin/0
hadoop jar my-job.jar
Benchmarking
This charm provides several benchmarks to gauge the performance of your environment.
The easiest way to run the benchmarks on this service is to relate it to the Benchmark GUI. You will likely also want to relate it to the Benchmark Collector to have machine-level information collected during the benchmark, for a more complete picture of how the machine performed.
However, each benchmark is also an action that can be called manually:
$ juju action do namenode/0 nnbench
Action queued with id: 55887b40-116c-4020-8b35-1e28a54cc622
$ juju action fetch --wait 0 55887b40-116c-4020-8b35-1e28a54cc622
results:
meta:
composite:
direction: asc
units: secs
value: "128"
start: 2016-02-04T14:55:39Z
stop: 2016-02-04T14:57:47Z
results:
raw: '{"BAD_ID": "0", "FILE: Number of read operations": "0", "Reduce input groups":
"8", "Reduce input records": "95", "Map output bytes": "1823", "Map input records":
"12", "Combine input records": "0", "HDFS: Number of bytes read": "18635", "FILE:
Number of bytes written": "32999982", "HDFS: Number of write operations": "330",
"Combine output records": "0", "Total committed heap usage (bytes)": "3144749056",
"Bytes Written": "164", "WRONG_LENGTH": "0", "Failed Shuffles": "0", "FILE:
Number of bytes read": "27879457", "WRONG_MAP": "0", "Spilled Records": "190",
"Merged Map outputs": "72", "HDFS: Number of large read operations": "0", "Reduce
shuffle bytes": "2445", "FILE: Number of large read operations": "0", "Map output
materialized bytes": "2445", "IO_ERROR": "0", "CONNECTION": "0", "HDFS: Number
of read operations": "567", "Map output records": "95", "Reduce output records":
"8", "WRONG_REDUCE": "0", "HDFS: Number of bytes written": "27412", "GC time
elapsed (ms)": "603", "Input split bytes": "1610", "Shuffled Maps ": "72", "FILE:
Number of write operations": "0", "Bytes Read": "1490"}'
status: completed
timing:
completed: 2016-02-04 14:57:48 +0000 UTC
enqueued: 2016-02-04 14:55:14 +0000 UTC
started: 2016-02-04 14:55:27 +0000 UTC
Status and Smoke Test
The services provide extended status reporting to indicate when they are ready:
juju status --format=tabular
This is particularly useful when combined with watch to track the on-going
progress of the deployment:
watch -n 0.5 juju status --format=tabular
The message for each unit will provide information about that unit's state.
Once they all indicate that they are ready, you can perform a "smoke test"
to verify that HDFS is working as expected using the built-in smoke-test
action:
juju action do namenode/0 smoke-test
After a few seconds or so, you can check the results of the smoke test:
juju action status
You will see status: completed if the smoke test was successful, or
status: failed if it was not. You can get more information on why it failed
via:
juju action fetch <action-id>
Monitoring
This charm supports monitoring via Ganglia. To enable monitoring, you must do both of the following (the order does not matter):
- Add a relation to the [Ganglia charm][] via the
:masterrelation - Enable the
ganglia_metricsconfig option
For example:
juju add-relation namenode ganglia:master
juju set namenode ganglia_metrics=true
Enabling monitoring will issue restart the NameNode and all DataNode components on all of the related compute-slaves. Take care to ensure that there are no running jobs when enabling monitoring.
Backup / HDFS export
This charm has an action called 'backup-hdfs' which will perform a distcp to a destination hadoop namenode. By default, the entire hdfs fs will be copied with the -update flag, meaning any non-existing files will be copied, and any different files will be overwritten. If the destination namenode is another juju deployment, be sure to run the command: 'juju expose namenode/?'. Otherwise make sure any firewalls are opened.
- The 'dest' param is mandatory and contains an ip or resolvable hostname for the destination hadoop namenode.
Example usage:
juju action do namenode/0 backup-hdfs dest='10.0.0.100'
This will run the following hadoop command as the hdfs user:
hadoop distcp -update hdfs://namenode-0:8020/ hdfs://10.0.0.100:8020/o
Other supported params are:
- srcpath: Specify a different source path to the default of /
- srcport: Specify a different HDFS port to the default of 8020
- destpath: Equivalent to srcpath for the destination
- destport: Equivalent to srcport for the destination
- update: Boolean, defaults to true, update files and create new files
- overwrite: Boolean, defaults to false, overrides update, copies everything
- options: Additional command line params to pass to the hadoop distcp command
If both update and overwrite are false, a standard distcp job will run.
Refer to apache distcp docs for further details: Hadoop 2.7.2 distcp docs.
Deploying in Network-Restricted Environments
The Apache Hadoop charms can be deployed in environments with limited network access. To deploy in this environment, you will need a local mirror to serve the packages and resources required by these charms.
Mirroring Packages
You can setup a local mirror for apt packages using squid-deb-proxy. For instructions on configuring juju to use this, see the Juju Proxy Documentation.
Mirroring Resources
In addition to apt packages, the Apache Hadoop charms require a few binary
resources, which are normally hosted on Launchpad. If access to Launchpad
is not available, the jujuresources library makes it easy to create a mirror
of these resources:
sudo pip install jujuresources
juju-resources fetch --all /path/to/resources.yaml -d /tmp/resources
juju-resources serve -d /tmp/resources
This will fetch all of the resources needed by this charm and serve them via a
simple HTTP server. The output from juju-resources serve will give you a
URL that you can set as the resources_mirror config option for this charm.
Setting this option will cause all resources required by this charm to be
downloaded from the configured URL.
You can fetch the resources for all of the Apache Hadoop charms
(apache-hadoop-namenode, apache-hadoop-resourcemanager,
apache-hadoop-slave, apache-hadoop-plugin, etc) into a single
directory and serve them all with a single juju-resources serve instance.
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