Can you explain what is meant by the term 'blue deployment' in the context of CI/CD?

Blue-Green Deployment is a deployment strategy where there are two identical environments: the current live environment (e.g., blue) and a new version of the application (green). The new version is deployed in the 'green' environment, parallel to the 'blue' environment, which serves users.

After successful testing and verification of the new version, traffic is switched from the blue environment to the green one. If something goes wrong, it can be quickly rolled back by switching traffic back to the blue environment. This minimizes downtime and risks during updates.

Example:

• Blue environment — the current version of the application serving users.
• Green environment — the new version deployed in parallel.
• The switch occurs at the load balancer or DNS level.

Thus, blue-green deployment provides a safe and controlled process for updates in CI/CD.