Navigating Azure Pipelines Output Variables Across Stages

In an advanced Azure Pipeline, managing stage dependencies and output variables is crucial for orchestration. For instance, when setting up a pipeline that operates on different test environments determined by the targetBranchName from incoming pull requests (PRs), capturing this information in one stage before proceeding with others can be beneficial.

Here’s how to refer output variables across stages and use them for branch-specific environmental setups:

Preparation Stage Setup of targetBranchName Variable

stages:
- stage: PrepareEnvironment
  jobs:
  - job: CaptureTargetBranch
    steps:
      - script: echo "Capturing target branch name for environment setup."
        continueOnError: true # Ensures the pipeline continues despite possible errors.
      
      - pwsh: Write-Output "[##vso[task.setvariable variable=targetEnvironmentName;isOutput=true]$(System.PullRequest.TargetBranch)]" 

In this snippet, we use PowerShell to set an output variable within the CaptureTargetBranch job under a preparation stage called PrepareEnvironment. The $(system.pullRequest.targetBranchName) is captured and stored as the environment’s target branch name for subsequent stages using its value in variables defined with [##vso[task.setvariable].

Note: Always ensure to check your pipeline’s documentation or a reliable resource, such as Microsoft DevOps guide on setting output variable (https://learn.microsoft.com/en-us/azure/devops/pipelines/process/variables?view=azure-devops&tabs=batch), for precise syntax and usage.

Referencing the Output Variable in Later Stage Conditions & Jobs

stages:
...
   - stage: DeployTestEnvironment
     dependsOn: PrepareEnvironment
     
     variables:
       branchNameVariable: $[stageDependencies.PrepareEnvironment.CaptureTargetBranch.outputs['targetEnvironmentName']]
       
     jobs:
       - job: DetermineAndSetVariables
         condition: and(not(contains(variables, 'branchNameVariable')), eq(parameters.envType, 'testing'))  # Assuming an environment type parameter is provided for conditional testing environments setup  
         
           steps:
             ...       
             
       - job: ExecuteTestJobs   
         dependsOn: DetermineAndSetVariables     
           

In the DeployTestEnvironment stage, we are setting up a condition and variable (branchNameVariable) that relies on output from previous stages. Here you can see how $(stageDependencies) syntax is used to access variables set in earlier jobs within your pipeline’s context: specifically retrieving our previously captured target branch name for environment setup using the stage-specific variables section under a conditional job named DetermineAndSetVariables.

Then, we have another dependent step with $(branchNameVariable) which allows us to further process and deploy tests specific only when certain environmental conditions are met (e.g., testing branch type parameter is given). The condition ensures that this stage runs exclusively for the intended test environments defined by envType parameters or absent branches, adding an extra layer of logic control within your CI/CD pipeline’dicts

Remember to replace any placeholders with actual variable names and conditions relevant to your workflow. This way, you maintain a clean separation between stage jobs while enabling the flow-dependent data handling necessary for complex deployment scenarios in Azure Pipelines.