How to pass output variables to multiple stages in Azure Pipelines?

In any continuous integration and deployment (CI/CD) pipeline, there are various stages that the code goes through before being deployed to production. Each stage may require input from the previous stage and may also produce output that needs to be passed on to the next stage. In Azure Pipelines, this can be achieved using output variables.

Output variables are variables that are set in a stage and passed on to the subsequent stages as input variables. This enables the different stages of the pipeline to communicate with each other and work together seamlessly. In this blog post, we will discuss how to pass output variables to multiple stages in Azure Pipelines.

Step 1: Define Output Variables in the Stage

The first step is to define the output variables in the stage where they are being set. This can be done using the syntax $(variableName). For example, if we want to set an output variable named "buildVersion" with a value of "1.0.0", we can add the following line in our YAML file:

- script: |

    echo "##vso[task.setvariable variable=buildVersion]1.0.0"

This will set the output variable "buildVersion" with the value "1.0.0".

Step 2: Pass Output Variables to Subsequent Stages

Once the output variables have been defined in the stage, they need to be passed on to the subsequent stages. This can be done by adding a dependency between the stages and specifying the input variables.

For example, let's say we have three stages in our pipeline: "Build", "Test", and "Deploy". We want to pass the output variable "buildVersion" from the "Build" stage to the "Test" and "Deploy" stages.

stages:

- stage: Build

  jobs:

  - job: BuildJob

    steps:

    - script: |

        echo "##vso[task.setvariable variable=buildVersion]1.0.0"

- stage: Test

  dependsOn: Build

  variables:

    buildVersion: $[ stageDependencies.Build.BuildJob.outputs['BuildJob.buildVersion'] ]

  jobs:

  - job: TestJob

    steps:

    - script: |

        echo "Build version: $(buildVersion)"

- stage: Deploy

  dependsOn: Test

  variables:

    buildVersion: $[ stageDependencies.Test.TestJob.outputs['TestJob.buildVersion'] ]

  jobs:

  - job: DeployJob

    steps:

    - script: |

        echo "Deploying version: $(buildVersion)"

In the above example, the "Test" stage depends on the "Build" stage and sets the input variable "buildVersion" to the output variable of the "Build" stage. Similarly, the "Deploy" stage depends on the "Test" stage and sets the input variable "buildVersion" to the output variable of the "Test" stage.

Step 3: Use Input Variables in the Subsequent Stages

Once the output variables have been passed on to the subsequent stages as input variables, they can be used in the subsequent stages using the syntax $(variableName).

In the above example, the input variable "buildVersion" is used in the "Test" and "Deploy" stages using the syntax $(buildVersion). This will use the value of the output variable "buildVersion" that was set in the previous stage.

Conclusion

In conclusion, passing output variables to multiple stages in Azure Pipelines is a straightforward process that involves defining output variables in the stage where they are set and passing them on to the subsequent stages as input variables. This enables the different stages of the pipeline to communicate with each other and work together seamlessly.

Setup Output Variables in Azure Pipelines for downstream Jobs