ASGs + Zookeeper is really easy, but you have to use https://github.com/soabase/exhibitor https://github.com/soabase/exhibitor. It coordinates replacing downed

ASGs + Zookeeper is really easy, but you have to use https://github.com/soabase/exhibitor https://github.com/soabase/exhibitor. It coordinates replacing downed ZK nodes using S3, and also provides a bunch of extra management tools. I had a single Zookeeper ASG running under load for over three years without maintenance. I pinged my old co-founder to see if he's willing to open source the CloudFormation template.