如何根据 System.PullRequest.TargetBranch 和 System.PullRequest.SourceBranch 的值决定在扩展模板中运行某个步骤

Question

我有三级嵌套的 Azure DevOps yaml 模板。在我的第二级嵌套模板中，我想根据拉取请求的目标分支有条件地调用第三级模板。

例如仅当拉取请求目标分支是 Main 时才应调用 level3@templates。

我知道 System.PullRequestTargetBranch 在模板中不可用。我也很熟悉

https://learn.microsoft.com/en-us/azure/devops/pipelines/process/variables?view=azure-devops&tabs=yaml%2Cbatch#runtime-expression-syntax

以及预定义变量对嵌套模板的限制

https://learn.microsoft.com/en-us/azure/devops/pipelines/build/variables?view=azure-devops&tabs=yaml#system-variables-devops-services

我希望有人能够提出一些解决方法来解决这个问题。

感谢所有帮助。

我的yaml结构如下

main.yaml

resources:
  repositories:
    - repository: templates
      type: git
      name: MyProj/templates
      ref: refs/heads/main

extends:  
  template: extends/level1.yaml@templates
  parameters:     
    MY_STAGES:
      BUILD:
        displayName: "Build"
      L1Config:
          config1: "config1"

Level1.yaml

parameters:
  - name: MY_STAGES
    type: object
    default: {}
  - name: L1Config
    type: object
    default: {}
  
    
variables:  
  - name: var1
    value: "value1"
  - name: var2    
    value: "val2"

stages:
  - ${{ each MY_STAGE in parameters.MY_STAGES }}:
      - stage: ${{ MY_STAGE.key }}
        displayName: "Build"        
        jobs:
          - job: build_dev
            displayName: Build
            steps:
              - template: /jobs/level2@templates
                parameters:
                  L2Config: ${{ MY_STAGE.value.L1Config }}        

level2.yaml

parameters:
  - name: L2Config
    type: object
    default: {}
        
steps:
  - pwsh: Write-Host "Hello World!"   
  
  # This is the template I want to call conditionally, based on the PullRequest Target
  - ${{ if eq(variable['System.PullRequest.TargetBranch'], 'refs/heads/main') }}: 
    # I know above syntax does not work, I have just written it down as an example of what I wish had worked. 
    - template: /steps/level3@templates
      parameters:
        param1: value1

Answer 1

正如你所说，System.PullRequest.TargetBranch 和 System.PullRequest.SourceBranch 无法在编译时扩展。

没有现成的方法可以完全满足您的要求。 If 表达式无法获取 Pull Request Branch 的正确值。

您可以参考以下方法：

您可以将 Pipeline 拆分为两个 Pipeline。第一个 Pipeline 将用于获取 System.PullRequest.TargetBranch，然后使用 Powershell 脚本将值传递给第二个 Pipeline 中的参数值。

这是一个例子：

第一条管道：

pool:
  vmImage: windows-latest



steps:
- task: PowerShell@2
  inputs:
    targetType: 'inline'
    script: |
      $token = "$(pat)"      
      $url="https://dev.azure.com/{Orgname}/{Projectname}/_apis/pipelines/{PipelineRunID}/runs?api-version=5.1-preview"
      
      $token = [System.Convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes(":$($token)"))
      
      $JSON = "
      {
        
      
      
        `"resources`": {
          `"repositories`": {
            `"self`": {
              `"ref`": `"refs/heads/main`"
            }
          }
        },
        `"templateParameters`": {
          `"PullRequestref`":`"$(System.PullRequest.TargetBranch)`"
         },
      
      
      
      }"
      
      
      $response = Invoke-RestMethod -Uri $url -Headers @{Authorization = "Basic $token"} -Method Post -Body $JSON -ContentType application/json

第二条管道：

主要

resources:
  repositories:
    - repository: templates
      type: git
      name: MyProj/templates
      ref: refs/heads/main
parameters:
  - name: PullRequestref
    type: string
    default: refs/heads/test
extends:  
  template: extends/level1.yaml@templates
  parameters:     
    MY_STAGES:
      BUILD:
        displayName: "Build"
      L1Config:
          config1: "config1"

2级：

parameters:
  - name: L2Config
    type: object
    default: {}
        
steps:
  - pwsh: Write-Host "Hello World!"   
  

  - ${{ if eq(parameters.PullRequestref, 'refs/heads/main') }}: 
    
    - template: /steps/level3@templates
      parameters:
        param1: value1