What is Blue/Green Deployment?
Blue/green deployment is a tried-and-true approach for reducing downtime during application changes in production situations. It also helps to reduce risk during application changes. The current active version servicing live traffic is denoted as “Blue.” Meanwhile, “Green” is a staging area for the upcoming deployment.
Blue/Green deployment strategy allows for a seamless transition between versions. Before switching traffic, test and confirm the new application in the green environment. Blue/Green deployment is practical for enterprises that prioritize high availability. It is also helpful for firms that focus on continuous delivery.
Advantages Over Traditional Deployments
| Feature | Blue/Green Deployment | Traditional Deployment |
|---|---|---|
| Downtime | Minimal to zero downtime during deployment | Potential for downtime during updates |
| Risk Mitigation | Rollback to the Blue environment if issues arise in Green | Higher risk of introducing bugs or regressions |
| Testing & Validation | Facilitates thorough testing in a production-like environment | Limited testing opportunities before pushing updates to production |
Understanding Blue Deployment
The blue environment represents the production application, actively handling user traffic. Here is a breakdown of the essential components:
- The Blue environment is the application’s established version. It responds to live queries reliably.
- This environment replicates the production infrastructure, which includes servers, databases, and settings.
- The blue environment should be an exact clone of the production system.
- Updates are not applied to the blue environment. Instead, modifications are evaluated and verified in a green environment.
- If problems occur in the Green environment, the Blue environment can be used for a swift rollback. This helps reduce downtime.
Understanding Green Deployment
The Green environment acts as a staging area for new application deployments. Key features include:
- The Green environment is the same as the production system used for testing. It is used to evaluate and validate new application versions.
- The setup, hardware, and software in this environment are identical to those in the Blue environment.
- The Green environment is configured to mirror the production system. This is done to ensure reliable testing results.
- New code is deployed in the Green environment for intensive testing. Following testing, settings, and upgrades are moved to the production environment.
- If problems emerge in the Green environment, return to the prior version in the Blue environment.
Comparing Blue vs. Green Deployment
| Feature | Blue Deployment | Green Deployment |
|---|---|---|
| State | Currently serving live traffic | Staging ground for new deployments |
| Risk Profile | Lower risk; established version | Higher risk; new, untested version |
| Downtime During Deployment | N/A (updates occur in Green) | N/A (updates occur in Green) |
| Downtime During Rollback | Potential downtime if rollback to Blue is necessary | Minimal downtime |
Best Practices for Blue/Green Deployment
Follow these best practices while deploying the Blue/Green strategy:
1. Integrate automation tools to streamline testing and deployment processes within the Green environment.
2. Monitor the health of Blue and Green environments. Perform continuous checks to identify issues in both environments.
3. Use Infrastructure as Code (IaC) tools to configure infrastructure in one consistent way for both environments.
4. Gradually roll out the new version to a small subset of users in the Green environment before complete migration.
5. Establish clear rollback procedures to ensure a swift reversion to the previous version if problems arise in Green.