Blue/green deployment is a release strategy that reduces downtime and risk by running two identical production environments called Blue and Green. This approach is particularly valuable for AWS developers seeking to minimize deployment risks while maintaining application availability.
In this stra…Blue/green deployment is a release strategy that reduces downtime and risk by running two identical production environments called Blue and Green. This approach is particularly valuable for AWS developers seeking to minimize deployment risks while maintaining application availability.
In this strategy, the Blue environment represents the current production version serving live traffic, while the Green environment hosts the new application version. Both environments are identical in infrastructure configuration, ensuring consistency during the transition.
The deployment process works as follows: First, you deploy your new application version to the Green environment while Blue continues handling all production traffic. Next, you thoroughly test the Green environment to validate functionality, performance, and stability. Once testing confirms the new version works correctly, you switch traffic from Blue to Green using a router, load balancer, or DNS change.
AWS provides several services that support blue/green deployments. Elastic Beanstalk offers URL swapping between environments. Route 53 enables weighted routing policies to gradually shift traffic. Elastic Load Balancing allows you to register and deregister target groups. CodeDeploy supports blue/green deployments for EC2, ECS, and Lambda functions.
Key benefits include near-zero downtime during releases since traffic switching happens almost instantaneously. If issues arise in the Green environment, you can quickly roll back by redirecting traffic to the still-running Blue environment. This provides a reliable safety net for production deployments.
Cost considerations exist since you temporarily run duplicate infrastructure. However, you can terminate the old Blue environment after confirming the Green deployment is stable, reducing ongoing costs.
For Lambda functions, AWS CodeDeploy implements blue/green through traffic shifting between function versions using aliases. You can configure linear or canary deployment preferences to control how traffic moves between versions, providing granular control over the release process.
Blue/Green Deployment Strategy
What is Blue/Green Deployment?
Blue/Green deployment is a release strategy that reduces downtime and risk by running two identical production environments called Blue and Green. At any time, only one environment is live and serving all production traffic, while the other remains idle or is used for staging the next release.
How Blue/Green Deployment Works
1. Blue Environment (Current): This is your current production environment actively serving users.
2. Green Environment (New): This is an identical environment where you deploy and test your new application version.
3. Testing Phase: Once the new version is deployed to Green, you perform thorough testing, including smoke tests, integration tests, and validation.
4. Traffic Switch: After validation, you redirect all traffic from Blue to Green using a router, load balancer, or DNS change.
5. Rollback Capability: If issues arise, you can switch traffic back to the Blue environment, which still has the previous stable version.
Why Blue/Green Deployment is Important
• Zero Downtime: Users experience no interruption during deployments since traffic switching is nearly instantaneous.
• Easy Rollback: If the new version has problems, reverting to the previous version is as simple as redirecting traffic back.
• Risk Reduction: Testing can occur in a production-like environment before exposing real users.
• Disaster Recovery: The idle environment serves as a standby for quick recovery.
• CodeDeploy: Native Blue/Green deployment option for EC2, ECS, and Lambda
• Route 53: Weighted routing policies for gradual traffic shifting
• Elastic Load Balancing: Target group switching between Blue and Green
• ECS: Blue/Green deployments with Application Load Balancer
• Lambda: Traffic shifting between function versions using aliases
Exam Tips: Answering Questions on Blue/Green Deployment
• When a question mentions zero downtime deployment with instant rollback capability, Blue/Green is likely the answer.
• Remember that Blue/Green requires double the resources during deployment since both environments run simultaneously.
• For Elastic Beanstalk, look for keywords like swap URLs or environment swap - this indicates Blue/Green.
• CodeDeploy Blue/Green for EC2 creates new instances in the Green environment, unlike in-place deployments that update existing instances.
• For Lambda, Blue/Green is achieved through alias traffic shifting between two function versions.
• If the question emphasizes testing in production environment before release, Blue/Green allows this by testing the Green environment with production data.
• Compare with Rolling deployments: Rolling updates instances gradually, while Blue/Green switches all traffic at once.
• Compare with Canary deployments: Canary routes a small percentage of traffic first, while Blue/Green is an all-or-nothing switch.
• Questions about database migrations with Blue/Green should note that both environments must be compatible with the database schema during transition.
• Cost-related questions: Blue/Green is more expensive due to running duplicate infrastructure, but provides the safest rollback option.