Blue-green deployment pattern

In the blue-green deployment, you must keep two identical copies of the application's production infrastructure, one labelled blue and the other labelled green. At any given time, just one environment, say blue, is active. When planning a new release for deployment in a green environment, test it, route traffic to green, and go live. If something goes wrong after going live, you can easily switch to blue. One advantage of the blue-green deployment is the ability to quickly move between environments, making it more resilient to failure. However, this can result in additional costs and maintenance for your organisation. You must now manage two independent identical environments, one of which is idle.

In AWS, the developers use cloud formation to create an infrastructure template. The formation template is Infrastructure as Code (IaC) that contains all the resources with

configurations needed for your application. Using the cloud formation, you can maintain a different version of your organization's infrastructure in source control and use it to

quickly spawn up your application production infrastructure in AWS. Cloud formation templates can be used efficiently in case of blue-green deployment. You can delete your idle environment (which reduces cost) once the release is done. For subsequent release, run the cloud formation template to provision a new environment and follow blue-green deployment. It is good to create environments in separate VPCs because deleting VPC

will remove all the services provisioned underlying it.

The Blue-Green Deployment pattern is a software release management method that is used to minimise downtime and risk during the deployment of new application versions or updates. Two identical surroundings, referred known as "blue" and "green," coexist in this arrangement. This is how it works:

Current and New Environment: The "blue" environment represents the current production environment with the existing version of the application. The "green" environment is a duplicate of the "blue" but represents the new version to be deployed.

Testing and Verification: The new version is deployed to the "green" environment, which is separate from the production environment. This allows testing, verification, and validation of the new release without impacting end-users.

Switch Over: Once the new version in the "green" environment is tested and deemed stable, a "switch" is performed to redirect traffic from the "blue" environment to the "green" one. This transition is rapid and minimizes downtime.

Rollback: If issues are encountered after the switch, a rollback is straightforward by redirecting traffic back to the "blue" environment. This ensures that the production environment can be quickly restored in case of problems.

Environment Recycling: After the switch, the "green" environment becomes the new production environment, while the "blue" environment can be updated with the next version for future deployments. This recycling ensures that the two environments remain identical.

The figure below shows the swapping of stable and tested servers interacting with customers after each update.

Summary

The Blue-Green Deployment pattern is a software release strategy that maintains two identical environments: "blue" for the current production version and "green" for the new release. The new version is deployed to the "green" environment, enabling thorough testing and validation while the "blue" environment serves end-users. When the new version proves stable, a rapid switch redirects traffic to "green," minimizing downtime. If issues arise, a straightforward rollback to "blue" is possible. This pattern reduces downtime, offers a controlled testing environment, and simplifies the recovery process, making it a valuable approach in continuous delivery for safe and seamless application updates.