What is Blue-Green Deployment? Software development using the “blue environment” and a “green environment” is called “blue-green deployment,” and it’s a method for making software deployment safer and easier. There are two separate production environments, and new code gets pushed to the inactive one whenever it’s ready to be deployed. Following a successful test in production, a router can be set up to point at the environment that has been updated, ensuring a seamless transition. Use cases for Blue-Green Deployment Load balancing Load balancing is another potential use case for blue-green deployment. As long as the two production environments are on different servers (rather than virtual machines), a router can simply balance traffic between the two versions of the production environment because they are functionally identical. A/B testing A/B testing is yet another possible application for blue-green deployments. The updated version of your code would be loaded onto the blue environment and 50% of your user traffic would be directed to the blue version instead of the green version. Your new application will have an impact on your important KPIs, so you’ll be able to analyze how the two environments compare. Canary deployment A canary deployment is the process of releasing new features to a limited group of users before distributing them to the rest of the user base. This simple controlled test, like a canary in a coal mine, can be used to determine whether the new version of your code contains any catastrophic flaws. This can be done by directing a portion of your traffic to a new version of the code to observe how it performs with real traffic, before deploying the update to all of your users at once. Testing in production Even if every effort is taken to ensure that the staging environment and the production are similar, there will always be minor variances. As a result, there may be issues and bugs that aren’t found until after the code has been deployed to the live system. Code may be tested in production by deploying it to the production environment and observing how it works before easily moving it to production traffic and real users. Continuous Integration/Continuous Delivery (CI/CD) As a DevOps technique, continuous integration aims to expedite the development process by automating testing and integrating new code often. By allowing more code to be pushed to production while reducing the risk of new releases, the blue-green deployment method can assist achieve this goal. Rollbacks Disaster recovery is a major advantage of blue-green deployments. For example, if new modifications are implemented in one environment (say, blue) but problems arise in another (green), a router can simply switch back to the old version of the code in the other environment with no downtime. Examples of Blue-Green Deployment In the case of a web application, your development team may be working on a new feature, but they want to avoid any downtime and make the transition to the new code as easy as possible. With a router directing traffic to the green version, you would set up two identical production environments (the “blue version” and the “green version”). After that, you’ll be able to apply the new changes to the production environment’s blue version and see how they work in action. You may discover that your production environment is plagued with issues that can be readily remedied by returning to development. To run a canary test on real users, you must first have confidence in the new version of the application’s performance and be able to direct a portion of your user traffic to the blue environment. To ensure a smooth feature release, you can move all of your traffic to the new environment without any concerns. The green environment can be readily rerouted to the previous version of your code if any errors are identified after the cutover has been completed. As soon as you are certain that the new code is error-free, you can copy the blue environment over to the green environment, resulting in two completely identical production settings once more. The second server can then be used as a load balancer if you see a sudden increase in traffic. Blue-Green Deployment vs. Feature flags Feature flags or feature toggles can be used as an alternative to blue-green deployment. Code can be wrapped in conditional code and turned on or off remotely with feature flags. There is no longer any need for two separate environments in which new features can be tested and rolled out in production. Additionally, feature flags can also be utilized for targeted rollouts, in which a feature is activated exclusively for a specified segment of your user traffic. Canary deployments and A/B testing, for example, are now possible without the need to manage two separate production systems.