Very quick and easy Cassandra (1.2) Installation on an EC2 (or really any) Ubuntu offering.

datastax_cassandra.sh

#!/bin/bash

###
#
# Find out which ami to use on http://www.alestic.com
#
# at the time of this writing, Ubuntu 12.04 (Precise) was ami-23d9a94a
# with EBS boot
#
# In order for this to work, tuned your firewall for the following:
# 
# 7000-7001
# 1024 - 65535
# 7199 TCP (JMX)
# 8012 TCP
# 8983 TCP
# 9042 TCP (BINARY PROTOCOL --- CQL3)
# 9160 TCP (THRIFT PROTOCOL)
# 22
# 8443
# 8888 (OPSCENTER)
#
###
#

### If this is going to be DEV --- probably just LVM, rather than a ton of disks
# install LVM, ntp
sudo apt-get -y -qq install lvm2 ntp

# fix date
sudo /etc/init.d/ntp stop && sudo ntpdate pool.ntp.org && sudo /etc/init.d/ntp start

# AWS Ubuntu instances take one of your ephemeral disks and mount it to /mnt by default
if [ "`mount | grep xvdb`" ]; then
  mntpoint=$(mount | grep xvdb | awk '{print $3}')
  sudo umount $(mount | grep xvdb | awk '{print $1}')
  sudo rm -rf $mntpoint
fi
if [ "`grep xvdb /etc/fstab`" ]; then
  sudo sed -i -e '/xvdb/d' /etc/fstab
fi

###
# Now let's find out which disk(s) we can use for LVM
#
# will end up with one (or multiple) listings such as:
#    202       32  440366080 xvdc
###
cat /proc/partitions | grep -vP "($(df -lh | grep -oP '(s|xv)d.\d?' | tr '\n' '|' | sed -e 's/|$//')|^$|major)"

###
# if you want to automate instead
# UNCOMMENT THE NEXT SET OF LINES JUST BELOW
###
OIFS=$IFS
IFS='$\n'
for disk in $(cat /proc/partitions | grep -vP "($(df -lh | grep -oP '(s|xv)d.\d?' | tr '\n' '|' | sed -e 's/|$//')|^$|major)"); do
#  size=$(echo $disk | awk '{printf "%0.f", $(NF-1)/1024/1024}')
#  echo "CREATING PHYSICAL GROUP FOR: /dev/$(echo $disk | awk '{print $NF}') --- SIZE: ${size}GB"
  sudo pvcreate /dev/$(echo $disk | awk '{print $NF}')
done
IFS=$OIFS

# total size available for LVM
data_size=$(cat /proc/partitions | grep -vP "($(df -lh | grep -oP '(s|xv)d.\d?' | tr '\n' '|' | sed -e 's/|$//')|^$|major)" | awk '{print $(NF-1)}' | awk '{sum+=$1} END {print sum*.6/1024/1024}')
clog_size=$(cat /proc/partitions | grep -vP "($(df -lh | grep -oP '(s|xv)d.\d?' | tr '\n' '|' | sed -e 's/|$//')|^$|major)" | awk '{print $(NF-1)}' | awk '{sum+=$1} END {print sum*.2/1024/1024}')

# Now create volume groups & logical volumes
sudo vgcreate cassandra $(for disk in $(cat /proc/partitions | grep -vP "($(df -lh | grep -oP '(s|xv)d.\d?' | tr '\n' '|' | sed -e 's/|$//')|^$|major)" | awk '{print $NF}'); do echo -n "/dev/$disk "; done)
sudo lvcreate --size ${data_size}G -n data cassandra
sudo lvcreate --size ${clog_size}G -n clog cassandra
#block_num=$(sudo lvdisplay /dev/cassandra/data | grep Block | awk '{print $NF}' | awk -F: '{print $1}')
#data_minor=$(sudo lvdisplay /dev/cassandra/data | grep Block | awk '{print $NF}' | awk -F: '{print $2}')
#clog_minor=$(sudo lvdisplay /dev/cassandra/clog | grep Block | awk '{print $NF}' | awk -F: '{print $2}')

# enable multiverse
OIFS=$IFS
IFS=$'\n'
for line in `grep multiverse$ /etc/apt/sources.list`; do
  newline=$(echo $line | sed 's/# //')
  sudo sed -i -e 's,'"$line"','"$newline"',' /etc/apt/sources.list
done
IFS=$OIFS
sudo apt-get -qq update

### install XFS and MDADM to RAID0 ephemeral disks
sudo DEBIAN_FRONTEND=noninteractive apt-get -y -qq install mdadm xfsprogs

# RAIIIIIIIIIIIIIID
# sudo /sbin/mdadm --create -l0 -n2 -c 256 /dev/md0 /dev/xvdc /dev/xvdd
# sudo mkdir /var/lib/cassandra
# echo "/dev/md0 /var/lib/cassandra xfs noatime,comment=raid-eph-cassandra 0 0" | sudo tee -a /etc/fstab
# echo DEVICE /dev/xvdb /dev/xvdc | sudo tee /etc/mdadm/mdadm.conf
# sudo mkfs.xfs /dev/md0
# sudo mount /var/lib/cassandra
# sudo blockdev --setra 65536 /dev/md0

# Make sure our newly made LVMs are XFS
sudo mkfs.xfs /dev/cassandra/data
sudo mkfs.xfs /dev/cassandra/clog
sudo mkdir -p /var/lib/cassandra/data
sudo mkdir -p /var/lib/cassandra/commitlog
echo "/dev/cassandra/data /var/lib/cassandra/data xfs noatime,comment=raid-eph-cassandra 0 0" | sudo tee -a /etc/fstab
echo "/dev/cassandra/clog /var/lib/cassandra/commitlog xfs noatime,comment=raid-eph-cassandra 0 0" | sudo tee -a /etc/fstab
sudo mount -a
sudo chown -R cassandra:cassandra /var/lib/cassandra/

# allow installs of Datastax
echo "deb http://debian.datastax.com/community stable main" | sudo tee -a /etc/apt/sources.list
curl -L http://debian.datastax.com/debian/repo_key | sudo apt-key add -

# Install Opscenter
sudo apt-get -qq update
sudo apt-get -y -qq install libssl0.9.8 opscenter-free

# allow it to listen on public interface
sudo sed -i -e 's/interface = 127.0.0.1/interface = 0.0.0.0/' /etc/opscenter/opscenterd.conf

### START'ER UP!
sudo service opscenterd start

###
#
# And you're just about ready to go.  You can now use OpsCenter to install any cluster
# of machines you'd like.  By giving it your EC2 credentials, it will launch a whole
# new set of machines for you, OR you can point already existing machines to it.
#
###

###
#
# Installing Cassandra 1.2.x on this machine
#
###

# let's install DSC12 (DataStax Cassandra 1.2)
sudo apt-get -y -qq install dsc12

###
#
# Now that it's installed... Configure it just a wee bit
#
# Change /etc/default/dse (for hadoop - HADOOP_ENABLED=1, for Solr - SOLR_ENABLED=1, Each node should be ONE role
#
###

# There are a lot of Cassandra options, so look them up, but bare minimum:
sudo sed -i -e "/^rpc_address/c\rpc_address: 0.0.0.0" -e "/^initial_token/c# initial_token:" /etc/cassandra/cassandra.yaml

# start cassandra up
sudo service cassandra start

###
# For opscenter-agent installs to work, must have installed your own ssh key:
#   using ssh-keygen -t rsa (to create one)
# into the authorized_keys file...
#
# ssh-keygen -t rsa
# cat ~/.ssh/id_rsa.pub | tee -a ~/.ssh/authorized_keys
####
ssh-keygen -q -t rsa -f ~/.ssh/id_rsa -N ""
cat ~/.ssh/id_rsa.pub | tee -a ~/.ssh/authorized_keys

# add this when trying to install opscenter-agent through opscenter
cat ~/.ssh/id_rsa