CCM (for Cassandra Cluster Manager ... or something)
====================================================

A script to create, launch and remove a Apache Cassandra cluster on localhost.

The goal of ccm is to make is easy to create, manage and destroy a small
cluster on a local box. It is meant for quick testing of a Cassandra cluster.


Install
-------

This requires a working python installation (tested with 2.7) with the pyYAML
module (http://pyyaml.org/ -- 'sudo easy_install pyYaml').

Once this repository cloned, you'll probably want to create a symbolic link to
the ccm executable script somewhere in your path (The following examples
assume that much).

ccm is only for cluster on localhost so if you want more than one node, you
will likely need multiple loopback interface aliases. On mac os x for
instance, you can create such aliases with
  sudo ifconfig lo0 alias 127.0.0.2 up
  sudo ifconfig lo0 alias 127.0.0.3 up
  ...

I'll assume you have at least 127.0.0.1, 127.0.0.2 and 127.0.0.3 set up in
the next section.


Usage
-----

ccm works from a Cassandra source tree (not the jars). So in the following
example, I assume that 'ccm' is in the path and that the current directory is
a Cassandra source directory (either 0.7 or trunk, this doesn't work with 0.6,
though that could be added easily if there is some interest). It also assumes
that Cassandra has been compiled (with 'ant build').

ccm works with the notion of a current cluster. To create a cluster and
'switch' to it:
> ccm create test

Then add some node:
> ccm add node1 -i 127.0.0.1 -j 7100 -s
> ccm add node2 -i 127.0.0.2 -j 7200 -s

This add 2 nodes on 127.0.0.1 and 127.0.0.2 using default thrift and storage
port using JMX port 7100 and 7200 (JMX binds itself to all interfaces by
default, so you want 2 separate ports here).
Moreover, those nodes are set as seeds ('-s' flag; you need at least one seed
node).

You can then start the whole cluster:
> ccm start

You can check that everything is working fine:
> ccm node1 ring

which simply calls nodetool ring on node1.

You can now bootstrap a new node and start it with:
> ccm add node3 -i 127.0.0.3 -j 7300 -b
> ccm node3 start

This will wait for node3 to be fully bootstrapped, so this will take around 90
seconds. You can use --no-wait to avoid this.

ccm then provides a few conveniences, like flushing a full cluster:
> ccm flush
or a single node:
> ccm node2 flush

You can also look at the log file of a given node with:
> ccm node1 showlog
(this exec 'less' on the log file)

And you can remove the whole cluster with:
> ccm remove

There is a bunch of other commands (some of nodetool commands are provided, just so that
you don't have to remember the IP addresses and port number). Just try 'ccm'
to get a list of available command. Then each command options are documented:
for instance 'ccm add -h' describe the option for 'ccm add'.


Where are things stored
-----------------------

By default, ccm stores all the node data and configuration files under ~/.ccm/cluster_name/.
This can be overridden using the --config-dir option with each command.


Notes
-----

I use this script almost daily for quick Cassandra testing, but this is *not*
heavily tested. You have been warned. I do welcome suggestions however.


Sylvain Lebresne <sylvain@datastax.com>