GitLab CI构建失败：无法获取Docker镜像内容描述符

环境参数 #

• 运行器：GitLab.com 共享运行器
• 访问令牌：已激活
• 远程仓库（另一GitLab.com仓库）：正常可用
• 远程Docker镜像：已存在

问题描述 #

2小时前构建一切正常，现在出现以下错误：

#1 [internal] load .dockerignore
#1 transferring context: 2B done
#1 DONE 0.0s
#2 [internal] load build definition from Dockerfile
#2 transferring dockerfile: 462B done
#2 DONE 0.1s
#3 [internal] load metadata for registry.gitlab.com/my_profile/nginx...
#3 ERROR: failed to copy: httpReadSeeker: failed open: could not fetch content descriptor sha256:acfa0a241e8726b03df9ef0765ecddda7588cbc751cb07b53ac999046297dbda (application/vnd.docker.container.image.v1+json) from remote: not found
------
 > [internal] load metadata for registry.gitlab.com/my_profile/nginx-php:php-8.1:
------
registry.gitlab.com/my_profile/nginx-php:php-8.1: failed to copy: httpReadSeeker: failed open: could not fetch content descriptor sha256:acfa0a241e8726b03df9ef0765ecddda7588cbc751cb07b53ac999046297dbda (application/vnd.docker.container.image.v1+json) from remote: not found
Cleaning up project directory and file based variables
00:01
ERROR: Job failed: exit code 1

排查建议 #

1. 检查镜像标签与哈希一致性
   确认registry.gitlab.com/my_profile/nginx-php:php-8.1标签是否被重新推送过，导致原哈希sha256:acfa0a241e8726b03df9ef0765ecddda7588cbc751cb07b53ac999046297dbda对应的镜像被删除或替换。可直接用镜像哈希拉取测试：

   docker pull registry.gitlab.com/my_profile/nginx-php@sha256:acfa0a241e8726b03df9ef0765ecddda7588cbc751cb07b53ac999046297dbda
   

2. 验证GitLab容器仓库权限
   确认访问令牌拥有该镜像仓库的读取权限，且未过期或被撤销。可在本地用该令牌登录仓库测试拉取：

   docker login registry.gitlab.com -u <用户名> -p <访问令牌>
   docker pull registry.gitlab.com/my_profile/nginx-php:php-8.1
   

3. 排查共享运行器网络问题
   GitLab.com共享运行器可能存在临时网络波动，尝试重新触发CI构建，或切换至其他可用的共享运行器（若有选项）。

4. 强制刷新镜像元数据缓存
   在CI配置中添加--no-cache参数，强制Docker重新拉取镜像元数据，避免缓存旧数据导致的问题：

   script:
     - docker build --no-cache -t <目标镜像名> .
   

内容的提问来源于stack exchange，提问作者Arkadiusz G.