In Azure DevOps, a “stage” refers to a logical unit within a pipeline that represents a distinct phase or environment in your continuous integration and continuous deployment (CI/CD) process. Stages allow you to organize and manage the different steps of your CI/CD pipeline, providing control over how your software is built, tested, and deployed. Here are the key aspects of Azure DevOps stages:

1. Phases of CI/CD: Stages represent the various phases or steps in your CI/CD process. Common stages include “Build,” “Test,” “Dev,” “Staging,” and “Production,” but you can define stages that align with your specific workflow.

2. Parallel and Sequential Execution: Stages can be executed in parallel or sequentially, depending on your requirements. Parallel execution allows multiple stages to run concurrently, speeding up the overall pipeline. Sequential execution ensures that one stage completes before the next one starts.

3. Jobs: Each stage consists of one or more “jobs.” A job represents a collection of steps that run on the same agent. Jobs within a stage can be configured to run concurrently or sequentially.

4. Artifacts: Stages can pass artifacts (e.g., build outputs, deployment packages) between them. Artifacts generated in one stage can be consumed by subsequent stages in the pipeline. This allows for a smooth flow of code and resources throughout the pipeline.

5. Environment Variables: You can define environment-specific variables and secrets for each stage. This allows you to customize the behavior of your pipeline at each stage without modifying the code.

6. Deployment Targets: In deployment stages (e.g., “Staging” and “Production”), you specify the target environment where your application or service will be deployed. This can include Azure resources like Azure App Service, Kubernetes clusters, virtual machines, or other platforms.

7. Manual Intervention: Stages can include manual approval gates before proceeding to the next stage. This is useful for ensuring that deployments to critical environments like production are validated by team members.

8. Retries and Conditions: You can configure stages to retry failed jobs or set conditions that determine whether a stage should run based on specific criteria (e.g., trigger on a specific branch).

9. Post-deployment Actions: After a deployment stage, you can configure post-deployment actions such as running tests, sending notifications, or cleaning up resources.

10. Logging and Monitoring: Azure DevOps provides extensive logging and monitoring capabilities for each stage, allowing you to track the progress and status of each job and step.

11. Customization: Stages are highly customizable. You can define custom conditions, scripts, and steps to tailor each stage to your specific needs.

12. Artifact Retention: Azure DevOps allows you to specify how long artifacts generated in a stage should be retained, helping to manage storage costs.

Example Usage: Here’s a simplified example of a multi-stage Azure DevOps YAML pipeline for a .NET application:

In this example, the pipeline has stages for building, testing, and deploying the application to the development environment. Additional stages can be added for staging and production deployments. Each stage is defined in YAML, making it easy to version, maintain, and automate your CI/CD process.