blue-green

## What I do - Design and implement blue-green deployment architectures - Manage environment switching and traffic routing - Create automated rollback procedures - Build deployment automation pipelines - Monitor environment health during transitions - Coordinate database and state changes across environments ## When to use me - When deploying applications requiring zero downtime - When you need quick rollback capabilities - When testing in production-equivalent environments - When managing stateful applications with complex data requirements - When implementing disaster recovery strategies - When performing infrastructure migrations ## Key Concepts ### Environment Setup ```yaml # Terraform example for blue-green infrastructure resource "aws_lb" "main" { name = "main-lb" load_balancer_type = "application" subnets = aws_subnet.public[*].id } resource "aws_lb_target_group" "blue" { name = "blue-tg" port = 80 protocol = "HTTP" vpc_id = aws_vpc.main.id } resource "aws_lb_target_group" "green" { name = "green-tg" port = 80 protocol = "HTTP" vpc_id = aws_vpc.main.id } ``` ### Deployment Workflow 1. **Deploy** new version to inactive environment (green) 2. **Verify** green environment passes health checks 3. **Route** traffic from blue to green 4. **Monitor** green environment under production load 5. **Keep** blue environment running for rollback 6. **Decommission** old environment after verification ### Key Patterns - **Immutable Infrastructure**: Recreate environments from scratch each deployment - **Feature Flags**: Toggle features independently of deployments - **Database Migrations**: Use backward-compatible schemas - **Connection Draining**: Gracefully move connections during switch - **Canary Analysis**: Start with small traffic percentage before full switch