Blue/green deployments with Amazon EC2 Auto Scaling Groups

AWS EC2 Auto Scaling Groups (ASGs) are a fundamental tool for cloud deployments, enabling virtual machines to scale according to demand and replace failed instances. Blue/green deployments, which utilize two stacks—one active and one inactive—minimize downtime and mitigate deployment risks by allowing the inactive stack to be updated with new application versions. This setup becomes live only after successful health checks, with the ability to revert if issues arise. Implementing blue/green deployments with ASGs involves creating necessary AWS infrastructure, such as Virtual Private Clouds (VPCs), subnets, load balancers, security groups, and AMIs. The process is further streamlined using Octopus Deploy to automate steps like determining active/inactive target groups, updating ASG launch templates with new AMIs, initiating instance refreshes, and adjusting listener rules to shift traffic. This methodology ensures a seamless and automated deployment process, reducing the potential for errors and allowing for easy rollback if needed.