Simple Cassandra Instance In AWS EC2
I’ve been doing Cassandra development in an enterprise setting for quite a while now. And being a good little development shop (Expedia), we had Chef set up to deploy stuff for us, including Cassandra installation. Chef is great at doing just that. The downside to that is that you forgot the details of how to install Cassandra manually. Here are the steps to spin up an EC2 instance and getting a single instance of Cassandra running on it.
AWS setup
First of all, you must have an Amazon Web Services (AWS) account to do this. Just do it, you’ll thank me once you see all the cool things you can do with it. Once you’re signed up, log into the AWS console and go to the EC2 dashboard. Click on the big “Launch Instance” button (I know, they make it easy, huh). My personal preference is CentOS, but you can pick whatever flavor of Unix you like. I typically go to the AMI Marketplace over the Community AMI area. I know I can trust the marketplace, whereas the other, I can’t trust to not have extra bloat pre-installed. From the Marketplace, I select the latest version of CentOS. In this case, CentOS 6.5.
The next step is to select your instance size. This decision can affect your wallet greatly. AWS offers a free tier for new users to have a micro instance running non-stop for free for the first year. Now, since I’m way past the first year on my AWS usage, I’ll only pay a couple cents per hour for use. But if you’re not careful, you can rack up a pretty good sized bill. I went with a m1.small instance.
Connect to EC2
Once you have your Linux VM up and running in EC2, you’ll need to connect to it. If you’re on a Mac, you can simply “ssh” into it. If you are on a PC, then you’ll need to download a third-party tool to connect. I like using “cmder”, available here. It’s probably the most similar to “ssh-ing” from a Mac. The following is my connection. Note, I have a pem file that I’m passing to it. This is the public/private key that you can set up. Highly advise using this method to get in and out of EC2 instances.
ssh -i c:\adamhutson.pem root@ec2-54-91-46-126.compute-1.amazonaws.comJava setup
First thing, does your VM have Java 7 installed on it? Run the following to find out:
java -versionIf it’s not installed, as is the case with most vanilla CentOS images, you’ll receive the following response:
-bash: java: command not foundSo we’ll need to download the JDK for Java 7 and install it. Run the following:
cd /opt/
curl -b oraclelicense=accept-securebackup-cookie -O -L http://download.oracle.com/otn-pub/java/jdk/7u67-b01/jdk-7u67-linux-x64.tar.gz
tar xzf jdk-7u67-linux-x64.tar.gz
cd /opt/jdk1.7.0_67/So now, we’ve downloaded and unzipped the JDK to the cd/opt/ folder, and then navigated into the new JDK folder.
alternatives --install /usr/bin/java java /opt/jdk1.7.0_67/bin/java 2
alternatives --config java
alternatives --install /usr/bin/jar jar /opt/jdk1.7.0_67/bin/jar 2
alternatives --install /usr/bin/javac javac /opt/jdk1.7.0_67/bin/javac 2
alternatives --set jar /opt/jdk1.7.0_67/bin/jar
alternatives --set javac /opt/jdk1.7.0_67/bin/javacLet’s re-check the version of Java now that we have the JDK 7 installed:
java -versionShould receive the following now:
java version "1.7.0_67"
Java(TM) SE Runtime Environment (build 1.7.0_67-b01)
Java HotSpot(TM) 64-Bit Server VM (build 24.65-b04, mixed mode)Now we need to set up some environment variables:
export JAVA_HOME=/opt/jdk1.7.0_67
export JRE_HOME=/opt/jdk1.7.0_67/jre
export PATH=$PATH:/opt/jdk1.7.0_67/bin:/opt/jdk1.7.0_67/jre/binCassandra install
We need a place to store our Cassandra files that we will be downloading. I choose to have a generic “cassandra” folder in the root.
mkdir /cassandra
cd /cassandraThere are two different ways to run Cassandra. The first is to download the tar and run it manually. The other is to get an rpm and install it as a service.
Option 1: Manually
curl -OL http://www.apache.org/dist/cassandra/2.1.0/apache-cassandra-2.1.0-bin.tar.gz
tar xzf apache-cassandra-2.1.0-bin.tar.gz
cd apache-cassandra-2.1.0
bin/cassandra -fNote the -f option that we passed the Cassandra binary. This tell Cassandra to run and output messages to the foreground. This is really nice to see what is going on. You can also leave that -f option off and not see any output. With it, you should receive a ton of output messages. However, it will stop outputting and the last couple lines should be like the following: (Note the last line that it is “Listening for thrift clients”)
INFO 14:33:44 Starting listening for CQL clients on localhost/127.0.0.1:9042...
INFO 14:33:44 Binding thrift service to localhost/127.0.0.1:9160
INFO 14:33:44 Listening for thrift clients...Now we have Cassandra running in the foreground, we’ll need to open a new tab and ssh into the box again. If we hadn’t used that -f, you could have reused the same ssh connection as above.
cd /cassandra/apache-cassandra-2.1.0
bin/cqlshWe are now connected to that running instance of Cassandra via the cqlsh interface. The following is the first part of the response for the cqlsh command line.
Connected to Test Cluster at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 2.1.0 | CQL spec 3.2.0 | Native protocol v3]
Use HELP for help.
cqlsh>To stop this installation of Cassandra from running, it’s a two-step procedure. First we grep to get the pid that it’s running under and then kill the pid.
ps aux | grep cassandra
kill 1234Option 2: As a service
curl -OL http://rpm.datastax.com/community /noarch/cassandra21-2.1.0-1.noarch.rpm
rpm -i cassandra21-2.1.0-1.noarch.rpmShould receive the following, letting you know that the service has started.
service cassandra start
Starting Cassandra: OKYou can also query the service to see if it’s running:
service cassandra statusShould receive the following, with a different pid, of course:
cassandra (pid 24356) is running...Let’s connect to it to see if it responds:
cd /usr/bin
cqlshShould receive the following to know that you are now inside the cqlsh prompt interact with Cassandra data models:
Connected to Test Cluster at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 2.1.0 | CQL spec 3.2.0 | Native protocol v3]
Use HELP for help.
cqlsh>It’s a service, so the normal service command are what you will use to stop it.
service cassandra stopStart using Cassandra
That’s it. Now go on your merry way and spin up your own.