如何修复Azure DevOps YAML管道中的“Unexpected state while attempting to read the mapping end”错误

在配置Azure DevOps多步骤YAML管道时，遇到Unexpected state while attempting to read the mapping end错误，报错指向steps区域，具体提示如下：

解析管道YAML时遇到错误：/azure-pipelines.yml
(行: 16, 列: 3): 映射中至少需要一个键值对 /azure-pipelines.yml: Unexpected state while attempting to read the mapping end. State:

MappingState: IsStart: True Index: 0 IsKey: False IsEnd: False

SequenceState: IsStart: False Index: 1 IsEnd: False

MappingState: IsStart: False Index: 3 IsKey: False

IsEnd: False

错误的YAML代码示例：

name: $(Date:yyyyMMdd)$(Rev:.r)

resources:
  repositories:
  - repository: Infrastructure
    type: git
    name: Infrastructure

trigger:
  paths:
    include:
    - source/project.test/**
    - source/project.test2/**

steps:
- ${{ if contains(variables['Build.SourceBranch'], 'refs/heads/main') }}:
    - template: Build/build-templateone.yml@Infrastructure
      parameters:
        appName: 'example'
  condition: eq(variables['Build.Reason'], 'IndividualCI')  

- ${{ if contains(variables['Build.SourceBranch'], 'refs/heads/main') }}:
    - template: Build/build-templatetwo.yml@Infrastructure
      parameters:
        appName: 'example'
  condition: eq(variables['Build.Reason'], 'IndividualCI')

错误原因 #

问题出在steps区域的结构写法：将condition字段放在了${{ if }}条件块的外部。YAML解析器无法识别这种结构，因为${{ if }}块本身是用来条件化插入步骤序列的，块外的condition没有对应的父级映射，导致解析时出现映射结构不完整的错误。

修复方案 #

方案1：合并条件到编译阶段判断

将分支判断和构建原因判断合并到${{ if }}的逻辑中，在编译阶段就决定是否插入步骤：

name: $(Date:yyyyMMdd)$(Rev:.r)

resources:
  repositories:
  - repository: Infrastructure
    type: git
    name: Infrastructure

trigger:
  paths:
    include:
    - source/project.test/**
    - source/project.test2/**

steps:
- ${{ if and(contains(variables['Build.SourceBranch'], 'refs/heads/main'), eq(variables['Build.Reason'], 'IndividualCI')) }}:
    - template: Build/build-templateone.yml@Infrastructure
      parameters:
        appName: 'example'

- ${{ if and(contains(variables['Build.SourceBranch'], 'refs/heads/main'), eq(variables['Build.Reason'], 'IndividualCI')) }}:
    - template: Build/build-templatetwo.yml@Infrastructure
      parameters:
        appName: 'example'

方案2：将condition作为步骤属性放在块内

保持${{ if }}的分支判断，同时把condition移到块内的步骤定义中，作为步骤的运行阶段判断条件：

name: $(Date:yyyyMMdd)$(Rev:.r)

resources:
  repositories:
  - repository: Infrastructure
    type: git
    name: Infrastructure

trigger:
  paths:
    include:
    - source/project.test/**
    - source/project.test2/**

steps:
- ${{ if contains(variables['Build.SourceBranch'], 'refs/heads/main') }}:
    - template: Build/build-templateone.yml@Infrastructure
      parameters:
        appName: 'example'
      condition: eq(variables['Build.Reason'], 'IndividualCI')  

- ${{ if contains(variables['Build.SourceBranch'], 'refs/heads/main') }}:
    - template: Build/build-templatetwo.yml@Infrastructure
      parameters:
        appName: 'example'
      condition: eq(variables['Build.Reason'], 'IndividualCI')

方案区别 #

• 方案1：编译阶段就完成条件判断，只有当两个条件都满足时，步骤才会被加入到管道中，不会在管道视图中显示被跳过的步骤。
• 方案2：步骤会先被插入管道，在运行阶段再通过condition判断是否执行，被跳过的步骤会在管道视图中显示为“已跳过”状态。

内容的提问来源于stack exchange，提问作者johnny3210