If you have read my previous post, “Map-Reduce With Ruby Using Hadoop“, then you will know that firing up a Hadoop cluster is really simple when you use Whirr. Without even ssh’ing on the machines in the cloud you can start-up your cluster and interact with it. In this post I’ll show you that it is just as easy to fire up a Cassandra cluster on Amazon EC2.

Install Whirr

I will fly through the setup of Whirr quite quickly. All the commands you need are here, but if you want a more thorough explanation then see my other post, “Map-Reduce With Ruby Using Hadoop“.

I am assuming that you have Homebrew installed.

sudo brew update
sudo brew install maven
mkdir ~/src/cloudera
cd ~/src/cloudera
wget http://archive.cloudera.com/cdh/3/whirr-0.1.0+23.tar.gz
tar -xvzf whirr-0.1.0+23.tar.gz
cd whirr-0.1.0+23
mvn clean install
mvn package -Ppackage

Be patient with the above. There is a lot to install, so it will take some time. Maven installs a lot of dependencies if it is your first time using it.

The good news is that from here on you are setup to easily fire-up your Amazon EC2 cluster for Cassandra, or Hadoop if you choose.

Whirr Configuration File

We will need to make a configuration file for Whirr to tell it that we want to launch a Cassandra cluster with 3 nodes. If you are brave, patient and have the cash, then you could just as easily fire-up a 100 node cluster (leave a comment if you do – there may be prizes!).

You will need to create a cassandra.properties file with the following contents…

whirr.service-name=cassandra
whirr.cluster-name=mycassandracluster
whirr.instance-templates=3 cassandra
whirr.provider=ec2
whirr.identity=<YOUR_AMAZON_EC2_ACCESS_KEY_ID_GOES_HERE>
whirr.credential=<YOUR_AMAZON_EC2_SECRET_ACCESS_KEY_GOES_HERE>
whirr.private-key-file=${sys:user.home}/.ssh/id_rsa

Replace the obvious fields with your Amazon EC2 Access Key ID and Amazon EC2 Secret Access Key.

Launch Your Cluster

Now you are ready to fire-up your Cassandra cluster. Simply use the following command and then be prepared to wait 5-10 minutes while Amazon builds your machines. This time is variable. Sometimes Amazon is quick, sometimes not so quick.

bin/whirr launch-cluster --config cassandra.properties


Launching mycassandracluster cluster
Configuring template
Starting 3 node(s)
Nodes started: [[id=us-east-1/i-13f25e7f, providerId=i-13f25e7f, tag=mycassandracluster, name=null, location=[id=us-east-1d, scope=ZONE, description=us-east-1d, parent=us-east-1], uri=null, imageId=us-east-1/ami-74f0061d, os=[name=null, family=amzn-linux, version=2010.11.1-beta, arch=paravirtual, is64Bit=true, description=amazon/amzn-ami-2010.11.1-beta.x86_64-ebs], userMetadata={}, state=RUNNING, privateAddresses=[10.204.99.163], publicAddresses=[50.16.155.106], hardware=[id=t1.micro, providerId=t1.micro, name=t1.micro, processors=[[cores=1.0, speed=1.0]], ram=630, volumes=[[id=vol-1657d47e, type=SAN, size=null, device=/dev/sda1, durable=true, isBootDevice=true]], supportsImage=hasRootDeviceType(ebs)]], [id=us-east-1/i-17f25e7b, providerId=i-17f25e7b, tag=mycassandracluster, name=null, location=[id=us-east-1d, scope=ZONE, description=us-east-1d, parent=us-east-1], uri=null, imageId=us-east-1/ami-74f0061d, os=[name=null, family=amzn-linux, version=2010.11.1-beta, arch=paravirtual, is64Bit=true, description=amazon/amzn-ami-2010.11.1-beta.x86_64-ebs], userMetadata={}, state=RUNNING, privateAddresses=[10.117.43.129], publicAddresses=[50.16.85.79], hardware=[id=t1.micro, providerId=t1.micro, name=t1.micro, processors=[[cores=1.0, speed=1.0]], ram=630, volumes=[[id=vol-1457d47c, type=SAN, size=null, device=/dev/sda1, durable=true, isBootDevice=true]], supportsImage=hasRootDeviceType(ebs)]], [id=us-east-1/i-11f25e7d, providerId=i-11f25e7d, tag=mycassandracluster, name=null, location=[id=us-east-1d, scope=ZONE, description=us-east-1d, parent=us-east-1], uri=null, imageId=us-east-1/ami-74f0061d, os=[name=null, family=amzn-linux, version=2010.11.1-beta, arch=paravirtual, is64Bit=true, description=amazon/amzn-ami-2010.11.1-beta.x86_64-ebs], userMetadata={}, state=RUNNING, privateAddresses=[10.117.46.170], publicAddresses=[184.73.100.203], hardware=[id=t1.micro, providerId=t1.micro, name=t1.micro, processors=[[cores=1.0, speed=1.0]], ram=630, volumes=[[id=vol-e857d480, type=SAN, size=null, device=/dev/sda1, durable=true, isBootDevice=true]], supportsImage=hasRootDeviceType(ebs)]]]
Authorizing firewall
Running configuration script
Completed launch of mycassandracluster
Started cluster of 3 instances
Cluster{instances=[Instance{roles=[cassandra], publicAddress=/50.16.85.79, privateAddress=/10.117.43.129}, Instance{roles=[cassandra], publicAddress=/50.16.155.106, privateAddress=/10.204.99.163}, Instance{roles=[cassandra], publicAddress=/184.73.100.203, privateAddress=/10.117.46.170}], configuration={}}

You now have your very own Cassandra cluster running in the cloud. Not so hard, hey!

Connect From Ruby

I will be following this post with step-by-step guide on how you can interact with your new cluster from your Ruby On Rails application. I recommend subscribing to the RSS feed to get updates to the blog.

Shutdown The Cluster

Here is how you can shutdown your cluster.

bin/whirr destroy-cluster --config cassandra.properties

Destroying mycassandracluster cluster
Cluster mycassandracluster destroyed

Conclusion

Whirr makes it very easy to start and stop a Cassandra cluster in the cloud without leaving the comfort of your laptop. What you do with that cluster is up to you, but I will be give you some ideas of what you could do in future posts.