如何修复CodeBuild中DOWNLOAD_SOURCE阶段的YAML_FILE_ERROR错误

问题现象 #

构建时DOWNLOAD_SOURCE阶段失败，报错信息如下：

Running on CodeBuild On-demand
Waiting for agent ping
Waiting for DOWNLOAD_SOURCE
Phase is DOWNLOAD_SOURCE
CODEBUILD_SRC_DIR=/codebuild/output/src2136787222/src
YAML location is /codebuild/output/src2136787222/src/buildspec.yml
DOWNLOAD_SOURCE State: FAILED
Phase context status code: YAML_FILE_ERROR Message: did not find expected key at line 15

问题原因 #

查看提供的buildspec.yml文件，第15行的post_build存在缩进错误：它前面多了一个空格，无法与同级的install、build保持一致层级，YAML解析器无法识别该键的正确位置，从而抛出错误。

错误片段示例：

build:
    commands:
      - echo Building frontend
      - npm run build
   post_build:  # 此处缩进3个空格，与install、build的2个空格缩进不一致
    commands:

修正方案 #

将post_build的缩进调整为2个空格，与install、build保持一致。修正后的完整buildspec.yml如下：

version: 0.2

phases:
  install:
    runtime-versions:
      nodejs: 16
    commands:
      - echo Entering dashboardclient directory
      - cd dashboardclient
      - echo Installing frontend dependencies
      - npm install
  build:
    commands:
      - echo Building frontend
      - npm run build
  post_build:  # 修正为2个空格缩进
    commands:
      - echo Frontend build complete
      - echo Listing contents of dashboardclient directory
      - ls -la  # Check current directory
      - ls -la dashboardclient  # Check contents of dashboardclient directory
      - echo Listing contents of build directory
      - ls -la dashboardclient/dist  # Check contents of build directory

artifacts:
  files:
    - '**/*'
  base-directory: 'dashboardclient/dist'

关键说明 #

YAML是严格依赖缩进的配置语言，所有同级配置项必须使用相同数量的空格缩进（通常为2个），层级错误会直接导致解析失败。调整缩进后重新触发构建即可解决该问题。

内容的提问来源于stack exchange，提问作者Mitema Emmanuel