This is a collection of tidbits I’ve picked up as I’ve worked through the last few posts about working with Amazon EC2. Nothing’s big enough to deserve its own post, so I’ve decided to lump them all together here.
Homebrew
If you’re running on Mac OS X, you can install the EC2 API command-line tools via Homebrew:
$ brew install ec2-api-tools
==> Downloading http://ec2-downloads.s3.amazonaws.com/ec2-api-tools-1.4.2.2.zip
######################################################################## 100.0%
==> Caveats
Before you can use these tools you must export some variables to your $SHELL
and download your X.509 certificate and private key from Amazon Web Services.
Your certificate and private key are available at:
http://aws-portal.amazon.com/gp/aws/developer/account/index.html?action=access-key
Download two ".pem" files, one starting with `pk-`, and one starting with `cert-`.
You need to put both into a folder in your home directory, `~/.ec2`.
To export the needed variables, add them to your dotfiles.
* On Bash, add them to `~/.bash_profile`.
* On Zsh, add them to `~/.zprofile` instead.
export JAVA_HOME="/System/Library/Frameworks/JavaVM.framework/Home"
export EC2_PRIVATE_KEY="$(/bin/ls $HOME/.ec2/pk-*.pem)"
export EC2_CERT="$(/bin/ls $HOME/.ec2/cert-*.pem)"
export EC2_HOME="/usr/local/Cellar/ec2-api-tools/1.4.2.2/jars"
Elastic IP addresses
If you’ve been following along at home, you probably noticed that when you start an EC2 instance it is assigned a new IP address by AWS. This isn’t much of a problem for S3-backed instances, as they pretty much restart from scratch every time you start them, but for EBS-backed instances it would be handy if we could get the same IP address every time. AWS gives us a way to do this, with elastic IP addresses.
First, you allocate a static IP address from AWS.
$ ec2-allocate-address
ADDRESS 50.17.204.89
As with EBS volumes, once you allocate an address, you start paying for it. The good news is, you don’t pay extra for it as long as it’s associated with a running EC2 instance.
$ ec2-describe-instances
RESERVATION r-f2b7df9f 331055354537 default
INSTANCE i-56857039 ami-76f0061f ec2-50-17-140-20.compute-1.amazonaws.com \
ip-10-212-170-227.internal running hrworx-keypair 0 \
m1.small 2011-03-16T22:35:15+0000 us-east-1a aki-407d9529 \
monitoring-disabled 50.17.140.20 10.212.170.227 ebs paravirtual \
xen
BLOCKDEVICE /dev/sda1 vol-90a783f8 2011-03-16T22:35:39.000Z
$ ec2-associate-address 50.17.204.89 -i i-56857039
ADDRESS 50.17.204.89 i-56857039
$ ec2-describe-instances
RESERVATION r-f2b7df9f 331055354537 default
INSTANCE i-56857039 ami-76f0061f ec2-50-17-204-89.compute-1.amazonaws.com \
ip-10-212-170-227.internal running hrworx-keypair 0 \
m1.small 2011-03-16T22:35:15+0000 us-east-1a aki-407d9529 \
monitoring-disabled 50.17.204.89 10.212.170.227 ebs paravirtual \
xen
BLOCKDEVICE /dev/sda1 vol-90a783f8 2011-03-16T22:35:39.000Z
Note that both the external IP address and the external name changed, to
50.17.204.89 and ec2-50-17-204-89.compute-1.amazonaws.com respectively.
When the EC2 instance is stopped or terminated, the IP address is disassociated, and you can associate it with a different EC2 instance (or the same one, if you restart it).