Introduction

As a seasoned C# and PowerShell developer, you’re likely familiar with the challenges of managing templates and their output variables in different pipelines within Azure DevOps. In this article, we’ll explore a common issue: how to pass outputs between discreet pipeline files, which isn’t directly supported by Azure DevOps. We’ll delve into a practical workaround involving the use of the Azure DevOps REST API to update a variable group, enabling seamless access across pipelines.

Problem Statement

Azure DevOps pipelines are powerful, but managing template output variables across different pipelines can be challenging. You might find that passing outputs directly between separate pipeline files isn’t supported out-of-the-box.

Scope of Output Variables in Azure DevOps

It’s crucial to understand that the scope of output variables in Azure DevOps is limited to the job in which they were set. This means that accessing output variables across different pipeline files directly is currently not supported in Azure DevOps. This limitation can pose a challenge when you need to share data or outputs between distinct pipelines.

jobs:
- job: Build
  steps:
    - script: |
        # Your build steps here
      displayName: 'Build'
- job: Deploy
  steps:
    - script: |
        # Your deploy steps here
      displayName: 'Deploy'

Workarounds for Sharing Data Across Pipelines

To address this limitation, you’ll need to employ alternative methods for sharing data across multiple pipelines. Three commonly used approaches are:

1. Updating a Variable Group

One effective method is to leverage variable groups in Azure DevOps. Variable groups allow you to define a set of variables that can be used across multiple pipelines. By updating the variable group using the Azure DevOps REST API, you can dynamically adjust the values of these variables, ensuring they are accessible in various pipelines.

- task: PowerShell@2
  displayName: 'Update Variable Group'
  inputs:
    targetType: 'inline'
    script: |
      $url = "$(System.CollectionUri)$(System.TeamProject)/_apis/distributedtask/variablegroups/{variableGroupId}?api-version=6.0-preview.2"
      $token = "YOUR_PERSONAL_ACCESS_TOKEN"
      $headers = @{
        "Content-Type" = "application/json"
        "Authorization" = "Basic $(System.AccessToken)"
      }
      $body = @{
        variables = @{
          'VariableName' = 'NewValue'
          # Add more variables as needed
        }
      } | ConvertTo-Json

      Invoke-RestMethod -Uri $url -Method PUT -Headers $headers -Body $body -UseBasicParsing
  • Replace YOUR_PERSONAL_ACCESS_TOKEN with the generated Personal Access Token.
  • Replace {variableGroupId} with the ID of the variable group you want to update.

2. Using Azure Redis Cache with Output Variable

You can leverage Azure Redis Cache and Azure Storage Account to store and retrieve output variables in your pipelines. This approach provides a reliable and scalable solution for sharing data across pipelines.

- task: PowerShell@2
  displayName: 'Use Azure Redis Cache'
  inputs:
    targetType: 'inline'
    script: |
      # Connect to Azure Redis Cache
      $redisHost = "your-redis-host.redis.cache.windows.net"
      $redisPort = 6380
      $redisKey = "$(YourRedisCacheKey)"

      $redisConnection = [Microsoft.Azure.Commands.RedisCache.Models.RedisCacheManagementClient]::new($redisHost, $redisPort, $redisKey)

      # Set a value in Redis Cache using an output variable
      $myValue = "$(OutputValue)"
      $redisConnection.StringSet("myKey", $myValue)

3. Using Azure Storage Account to Store Output Variable

Storing output variables in an Azure Storage Table can be a valid approach, depending on your specific use case and requirements. Azure Storage Tables are a NoSQL data storage service provided by Microsoft Azure that can store large amounts of structured data.

steps:
- powershell: |
    # Define your output variable
    $outputVariable = "Hello, Azure Storage Table!"

    # Authenticate with Azure using a service principal or other method
    # For simplicity, this example uses a Personal Access Token (PAT)
    $token = "YOUR_PERSONAL_ACCESS_TOKEN"
    az login --output none --service-principal --username http://azure-cli-2016-08-05-14-31-15 --password $token --tenant YOUR_TENANT_ID

    # Define variables for storage account and table
    $storageAccount = "yourstorageaccount"
    $tableName = "yourtablename"

    # Create a new entity in the table with the output variable
    az storage entity insert -t $tableName --account-name $storageAccount --partition-key "PartitionKey" --row-key "RowKey" --property @{"OutputVariable"="$outputVariable"} --if-none-match "*"

  displayName: 'Store Output Variable in Azure Storage Table'

Additional Insights from Stack Overflow

How to pass variables from one pipeline to another pipeline in azure devops:

This discussion suggests using a variable group to store values that you want to control and make available across multiple pipelines. Variable groups can also be utilized for storing secrets and other values that might need to be passed into a YAML pipeline. It’s important to note that this method is more suitable for sharing static values across builds and release pipelines.

Example:

Consider a scenario where you have a variable that represents a version number. If you need to ensure this version number is consistent across multiple pipelines, using a variable group would be an effective approach.

variables:
  - group: MyVariableGroup

Share variables across stages in Azure DevOps Pipelines:

This thread focuses on how to share variables across stages within a single Azure DevOps Pipeline. It mentions that output variables may now be used across stages in a YAML-based pipeline. This capability allows you to pass useful information, such as a go/no-go decision or the ID of a generated output, from one stage to the next.

jobs:
- job: Build
  steps:
    - script: |
        # Your build steps here
        echo "##vso[task.setvariable variable=GeneratedOutput;isOutput

=true]OutputValue"
      displayName: 'Build'
- job: Deploy
  dependsOn: Build
  steps:
    - script: |
        echo "$(Build.GeneratedOutput)"
      displayName: 'Deploy'

Passing variables between release pipelines in azure:

This post explains that output variables are created by the pipeline and referenced by the other tasks in the pipeline. It emphasizes that these variables cannot be defined statically, and their value can only be known after running the task in the pipeline.

jobs:
- job: Build
  steps:
    - script: |
        # Your build steps here
        echo "##vso[task.setvariable variable=GeneratedOutput;isOutput=true]OutputValue"
      displayName: 'Build'
- job: Deploy
  dependsOn: Build
  steps:
    - script: |
        echo "$(Build.GeneratedOutput)"
      displayName: 'Deploy'

Summary

In conclusion, we covered different scenarios where sharing data or variables is essential in the CI/CD process. It’s important to note that while Azure DevOps provides mechanisms for sharing data within a pipeline, passing variables directly between different pipeline files is currently not supported. As a workaround, methods like updating a variable group or utilizing external services or storage can be employed to achieve the desired outcome.

It’s essential to carefully evaluate your pipeline architecture and choose the approach that best suits your specific requirements. By adopting these workarounds, you can effectively manage template output variables across Azure DevOps pipelines, ensuring smooth and reliable CI/CD processes.

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