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

# 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