Cloudera Plugin
===============

The cloudera plugin is a Sahara plugin which allows the user to deploy and
operate a cluster with Cloudera Manager.

The cloudera plugin is not enabled in Sahara by default. To enable it you should
manually modify the Sahara configuration file (default /etc/sahara/sahara.conf)
to add "cdh" in "plugins" value.

.. sourcecode:: cfg

    plugins=cdh,vanilla,hdp,fake

To use the cloudera plugin, you should have cm_api (version >=8.0.0) installed
on the server where Sahara is running. To install cm_api, simply use pip:

.. sourcecode:: console

    sudo pip install cm_api

You need to build images using :doc:`cdh_imagebuilder` to produce images used
to provision cluster. They already have Cloudera Express 5.2.0 installed.

The cloudera plugin requires an image to be tagged in Sahara Image Registry with
two tags: 'cdh' and '<cloudera version>' (e.g. '5').

The default username specified for these images is different for each
distribution:

+--------------+------------+
| OS           | username   |
+==============+============+
| Ubuntu 12.04 | ubuntu     |
+--------------+------------+
| CentOS 6.5   | cloud-user |
+--------------+------------+


Cluster Validation
------------------

When the user creates or scales a Hadoop cluster using a cloudera plugin, the
cluster topology requested by the user is verified for consistency.

The following limitations are required in the cluster topology for the cloudera
plugin:

  + Cluster must contain exactly one manager.
  + Cluster must contain exactly one namenode.
  + Cluster must contain exactly one secondarynamenode.
  + Cluster can contain at most one resourcemanager and this process is also
    required by nodemanager.
  + Cluster can contain at most one jobhistory and this process is also
    requried for resourcemanager.
  + Cluster can contain at most one oozie and this process is also required
    for EDP.
  + Cluster can't contain oozie without datanode.
  + Cluster can't contain oozie without nodemanager.
  + Cluster can't contain oozie without jobhistory.