I have a simple web application deployed on a large instance with EC2. I now want to deploy the latest code to this server but I want to do this in a way which minimizes downtime and is a smooth as possible for the end user. Here is my plan:
- Fire up another large instance
- Install all the software layers on that instance
- Restore and attach an EBS drive to the instance
- Deploy our latest production ready code on the new instance
- Run all tests (including manual testing of the application)
- (If tests pass) Put a "Site Under Maintenance" notice on the live site.
- Backup the EBS instance on the live site
- Detach the EBS instance from the new server and replace with the latest backup
- Use ec2-associate-address to move the IP address to the new instance
- Sit back and wait for traffic to start flowing though the new instance
- Terminate the old instance
Does this seem like a good strategy? Are there any tutorials or books that might cover this topic? I have already read Cloud Application Architectures by George Reese, which is an excellent book, but does not cover deployment. Additionally, I know that there are tools that can help with this like RightScale or enStratus which I will use when I start using more than one instance.
Best Answer
This looks like a good overall approach. You could cut out step 2, and thus bring down the launch time, by creating a custom AMI that includes all the software layers you need; having said that, I would still update all of the packages at startup to make sure that you get all the latest security updates.
You might also want to think about using an EBS-backed instance - that way you could have the boot volume, the software stack and your application all on EBS, which would cut out a few of the steps above.