Cloud Application Architectures

Machine Image Design

Two indirect benefits of the cloud are:

• It forces discipline in deployment planning

• It forces discipline in disaster recovery

Thanks to the way virtualized servers launch from machine images, your first step in moving into any cloud infrastructure is to create a repeatable deployment process that handles all the issues that could come up as the system starts up. To ensure that it does, you need to do some deployment planning.

The machine image (in Amazon, the AMI) is a raw copy of your operating system and core software for a particular environment on a specific platform. When you start a virtual server, it copies its operating environment from the machine image and boots up. If your machine image contains your installed application, deployment is nothing more than the process of starting up a new virtual instance.

Amazon Machine Image Data Security

When you create an Amazon machine image, it is encrypted and stored in an Amazon S3 bundle. One of two keys can subsequently decrypt the AMI:

• Your Amazon key

• A key that Amazon holds

Only your user credentials have access to the AMI. Amazon needs the ability to decrypt the AMI so it can actually boot an instance from the AMI.

Don’t Store Sensitive Data in an AMI

Even though your AMI is encrypted, I strongly recommend never storing any sensitive information in an AMI. Not only does Amazon have theoretical access to decrypt the AMI, but there also are mechanisms that enable you to make your AMI public and thus perhaps accidentally ...