Branched images
Once we had our base image ready to go we rolled two instances, each one to be shaped to the role it will server: frontend and backend.
Customizing each image was pretty straightforward, install Apache with PHP on the frontend, and MySQL on the backend. Copy the Drupal over to the frontend, set the location of user files to be on the S3 mounted filesystem.
Regarding MySQL we have a simple design, MySQL runs off the local drive and binary logs are written to the S3 mounted filesystem (a different filesystem than that one used for the frontend). At a later stage we will setup database replication across the backend server.
Since database servers are not going to be overwhelmed with requests we are keeping an active-inactive configuration for the database servers rather than go with a more complex design for the databases (KISS!!!)
Next:
