Azure Pipelines循环内if条件失效问题排查与解决

问题场景 #

配置Azure Pipelines时遇到两个异常：

• 遍历branchMapping参数，尝试通过if条件匹配Build.SourceBranch为environment变量赋值，但变量输出为空
• 循环内判断Build.SourceBranchName与分支名的if语句无任何输出

原配置代码如下：

parameters:
  - name: containerRegistry
    displayName: Azure Container Registry Service Connection
    type: string
    default: 'acr-amaest'
    values:
      - acr-amaest

  - name: deploymentSteps
    type: stepList
    default:
      - script: echo "Add your deployment steps to your template"
        displayName: Empty deployment step

  - name: branchMapping
    type: object
    default:
      develop: build
      staging: staging
      main: release

variables:
  - name: environment
    ${{ each branch in parameters.branchMapping }}:
      ${{ if eq(variables['Build.SourceBranch'], 'refs/heads/${{ branch.Key }}') }}:
        value: ${{ branch.Value }}

stages:
- stage: Test
  displayName: 🚀 Test
  jobs:
    - job:
      steps:
        # Printing empty string
        - bash: |
            echo ${{ variables['environment'] }}
        # Works, prints everything
        - ${{ each branch in parameters.branchMapping }}:
          - bash: echo '${{ branch.Key }} -> ${{ branch.Value }} against ${{ variables['Build.SourceBranch'] }}'
        # Prints nothing    
        - ${{ each branch in parameters.branchMapping }}:
           - ${{ if eq(variables['Build.SourceBranchName'], '/${{ branch.Key }}') }}:
             - bash: echo "Coucou ${{ branch.Key }}"

问题原因 #

1. 嵌套表达式写法错误：
   原变量配置中，'refs/heads/${{ branch.Key }}'属于在字符串中嵌套模板表达式的错误写法。Azure Pipelines模板引擎不会解析单引号内的${{ ... }}表达式，会把整个内容当成普通字符串，导致eq判断永远不成立，environment变量无法被赋值。

2. Build.SourceBranchName匹配错误：
   Build.SourceBranchName变量本身就是分支名称（比如develop、main），不需要在前面加斜杠/，原代码中eq(variables['Build.SourceBranchName'], '/${{ branch.Key }}')的匹配条件永远不满足，所以不会执行对应的bash步骤。

修复方案 #

1. 修正environment变量赋值 #

使用Azure Pipelines内置的format函数来拼接分支路径字符串，确保表达式能正确解析branch.Key的值：

variables:
  - name: environment
    ${{ each branch in parameters.branchMapping }}:
      ${{ if eq(variables['Build.SourceBranch'], format('refs/heads/{0}', branch.Key)) }}:
        value: ${{ branch.Value }}

2. 修正Build.SourceBranchName的判断逻辑 #

去掉分支名前的斜杠，直接比较Build.SourceBranchName和branch.Key：

- ${{ each branch in parameters.branchMapping }}:
   - ${{ if eq(variables['Build.SourceBranchName'], branch.Key) }}:
     - bash: echo "Coucou ${{ branch.Key }}"

完整修复后示例 #

parameters:
  - name: containerRegistry
    displayName: Azure Container Registry Service Connection
    type: string
    default: 'acr-amaest'
    values:
      - acr-amaest

  - name: deploymentSteps
    type: stepList
    default:
      - script: echo "Add your deployment steps to your template"
        displayName: Empty deployment step

  - name: branchMapping
    type: object
    default:
      develop: build
      staging: staging
      main: release

variables:
  - name: environment
    ${{ each branch in parameters.branchMapping }}:
      ${{ if eq(variables['Build.SourceBranch'], format('refs/heads/{0}', branch.Key)) }}:
        value: ${{ branch.Value }}

stages:
- stage: Test
  displayName: 🚀 Test
  jobs:
    - job:
      steps:
        - bash: |
            echo ${{ variables['environment'] }}
        - ${{ each branch in parameters.branchMapping }}:
          - bash: echo '${{ branch.Key }} -> ${{ branch.Value }} against ${{ variables['Build.SourceBranch'] }}'
        - ${{ each branch in parameters.branchMapping }}:
           - ${{ if eq(variables['Build.SourceBranchName'], branch.Key) }}:
             - bash: echo "Coucou ${{ branch.Key }}"

内容的提问来源于stack exchange，提问作者Arnaud F.