There’s an excellent and practical write-up on configuring an EC2 container to host a WordPress site here.  But there are a few minor amplifications I’d add.  So I thought I’d write them up here.

1.) As some folks noted in the comments, you should assign the Elastic IP address before you install WordPress.  Everything with WP just seems to work much better when you do it in that order.

2.) You’ll want to configure your instance to autostart both Apache and Mysql.  Credit where it’s due: I got this information from here.

• sudo /sbin/chkconfig –add mysqld
• sudo /sbin/chkconfig –list mysqld
• sudo /sbin/chkconfig mysqld on
• sudo /sbin/chkconfig –add httpd
• sudo /sbin/chkconfig –list httpd
• sudo /sbin/chkconfig httpd on

You really don’t need the –list step in either case.  It’s just a way to insure you’ve got chkconfig command right. Note that those commands are specific to the CentOS image that Amazon provides.  If you’re hosting a different flavor of Linux, you’ll need to figure out the commands for your flavor.

Other than those two minor corrections, his guide is sound and well-written.