Windows自托管Runner替换::set-output后跨Job输出为空的问题

在Windows自托管Github Actions Runner上，需获取前一个Job中步骤的执行结果。原本使用已废弃的::set-output命令可正常实现需求（最后步骤打印"success"），但替换为写入GITHUB_ENV的两种方式后，出现输出变量OUTPUT1为空、打印步骤报错的情况。

原工作流代码：

name: Debug workflow

on: workflow_dispatch
jobs:
  job1:
    runs-on: tester-1
    outputs:
      output1: ${{ steps.step1.outputs.MY_OUTPUT }}
    steps:
      - name: Checkout with submodules
        id: checkout_step
        uses: actions/checkout@v3
      - name: Write variable to output
        id: step1
        run: echo '::set-output name=MY_OUTPUT::${{ steps.checkout_step.outcome }}'
  job2:
    runs-on: tester-1
    needs: job1
    env:
      OUTPUT1: '${{needs.job1.outputs.output1}}'
    steps:
    - name: Print outputs from previous 
      run: echo ${{ env.OUTPUT1 }}

尝试替换的命令：

1. echo "MY_OUTPUT=${{ steps.checkout_step.outcome }}" >> $env:GITHUB_ENV
2. echo "MY_OUTPUT=${{ steps.checkout_step.outcome }}" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append

报错信息：

Run echo 
  echo 
  shell: C:\Windows\System32\WindowsPowerShell\v1.0\powershell.EXE -command ". '{0}'"
  env:
    OUTPUT1: 
Write-Output : Cannot process command because of one or more missing mandatory parameters: InputObject.
At C:\tester-1-runner\_work\_temp\a19d4f45-cf0e-4ddb-b62e-4f05a2f00461.ps1:2 char:1
+ echo
+ ~~~~
    + CategoryInfo          : InvalidArgument: (:) [Write-Output], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : MissingMandatoryParameter,Microsoft.PowerShell.Commands.WriteOutputCommand
 
Error: Process completed with exit code 1.

核心原因 #

混淆了GITHUB_ENV和GITHUB_OUTPUT的用途：

• 原::set-output的作用是给步骤的outputs赋值，供后续步骤、跨Job引用；
• 写入GITHUB_ENV仅能设置当前Job内的环境变量，无法被steps.step1.outputs.MY_OUTPUT读取，导致job1的outputs为空，进而使job2的OUTPUT1变量无值。

报错的直接触发点：当OUTPUT1为空时，PowerShell的echo（即Write-Output）命令缺少必填输入对象，因此抛出错误。

正确替换方案 #

要给步骤outputs传值，需写入GITHUB_OUTPUT文件，Windows PowerShell下推荐以下两种写法：

1. 使用Out-File避免编码问题：

echo "MY_OUTPUT=${{ steps.checkout_step.outcome }}" | Out-File -FilePath $env:GITHUB_OUTPUT -Encoding utf8 -Append

2. 使用Add-Content命令：

Add-Content -Path $env:GITHUB_OUTPUT -Value "MY_OUTPUT=${{ steps.checkout_step.outcome }}" -Encoding utf8

修正后的完整工作流 #

name: Debug workflow

on: workflow_dispatch
jobs:
  job1:
    runs-on: tester-1
    outputs:
      output1: ${{ steps.step1.outputs.MY_OUTPUT }}
    steps:
      - name: Checkout with submodules
        id: checkout_step
        uses: actions/checkout@v3
      - name: Write variable to output
        id: step1
        run: Add-Content -Path $env:GITHUB_OUTPUT -Value "MY_OUTPUT=${{ steps.checkout_step.outcome }}" -Encoding utf8
  job2:
    runs-on: tester-1
    needs: job1
    env:
      OUTPUT1: '${{needs.job1.outputs.output1}}'
    steps:
    - name: Print outputs from previous 
      run: echo ${{ env.OUTPUT1 }}

内容的提问来源于stack exchange，提问作者YogoWafel