Hadoop is a software platform that lets one easily write and run applications that process vast amounts of data. This charm manages the HDFS master node (NameNode).
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 2.4.1, which manages the distribution and replication of data among the various DataNode components.
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
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
juju action do 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
juju action fetch <action-id>
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
- Enable the
juju add-relation hdfs-master ganglia:master juju set hdfs-master 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.
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.
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.
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-plugin, etc) into a single
directory and serve them all with a single
juju-resources serve instance.
- (int) The default block size for new files (default to 64MB). Increase this in larger deployments for better large data set performance.
- (int) Default block replication. The actual number of replications can be specified when the file is created. The default is used if replication is not specified at file creation time.
- (boolean) Enable metrics using Ganglia. Note that enabling this option will have no effect if the service is not related to a ganglia service via the ganglia:master relation. Enabling this option with the relation will issue a restart to the NameNode and all DataNode components on all related compute-slaves. See the README for more information.
- (string) URL from which to fetch resources (e.g., Hadoop binaries) instead of Launchpad.