Blue/Green deployment

Blue/Green deployment is a software release strategy used in deployment pipelines to minimize downtime and reduce the risk associated with deploying new versions of an application. Primarily purpose of Blue/Green deployment is to ensure smooth transitions between different versions of software and allow easy rollbacks if any issues arise during deployment.

In a blue/green deployment, two separate environments are maintained: the “blue” environment (current live version) and the “green” environment (new version).

1. Blue Environment: This is the currently active and stable version of the application that is serving live traffic.
2. Green Environment: This is the new version of the application that you want to deploy. It is set up and configured in parallel with the blue environment but does not receive live traffic initially.

Typical Blue/Green deployment has following steps:

1. Deployment: The new version of the application is deployed to the green environment. This deployment is done without directing any live traffic to the green environment, so it doesn’t affect users.
2. Testing Phase: Once the deployment is complete, complete testing is conducted in the green environment. This can include automated tests, manual tests, performance tests, and any other relevant tests to ensure the new version functions correctly and meets quality standards.
3. Switching Traffic: If the testing phase is successful, the traffic routing is switched from the blue environment to the green environment. This can be done using various methods, such as updating DNS records, load balancer configurations, or routing rules.
4. Validation: After switching traffic, the green environment becomes the new live environment, serving user requests. This phase involves monitoring the application closely to ensure that everything is functioning as expected in the production environment.
5. Rollback: If any issues arise in the green environment after switching traffic, you can quickly revert to the blue environment to minimize downtime. This rollback mechanism is a significant advantage of the blue/green deployment strategy.
6. Cleanup: Depending on your setup and policies, the old blue environment can either be kept as a backup or decommissioned.

The main benefits of blue/green deployment include:

• Reduced Downtime: Users experience minimal to no downtime during the deployment process, as the switch between environments is typically quick.
• Reduced Risk: The ability to quickly switch back to the previous environment if issues are detected in the new version helps mitigate risks associated with deployments.
• Easier Rollbacks: Rolling back to the previous version is straightforward, promoting a safer and more reliable deployment process.
• Thorough Testing: The green environment provides an isolated space for comprehensive testing before exposing the new version to users.
• Scalability Testing: Blue/green deployments can also be used to test scalability by gradually routing more traffic to the green environment.

Implementing blue/green deployment might require specific tools, infrastructure, and automation, depending on the complexity of your application and deployment pipeline. Blue/Green deployment pipelines minimize downtime and reduce the risk associated with deploying new versions of an application. Primarily purpose of Blue/Green deployment is to ensure smooth transitions between different versions of software and allow easy rollbacks if any issues arise during deployment.