.m2 的 Docker 缓存在本地不起作用 [英] Docker caching of .m2 doesn't work locally

问题描述

考虑一下.gitlab-ci.yml:

variables:
     MAVEN_OPTS: "-Dmaven.repo.local=/root/.m2/repository"

cache:
     key: "M2"
     paths:
        - /root/.m2/repository

直接在gitlab中运行时这样可以正常工作，但是在本地运行时就不行了:

This works correctly when running directly in gitlab, but it doesn't work locally when running as:

gitlab-runner exec docker test

如果我像这样在本地运行它，我可以看到像 成功提取缓存 这样的消息，但随后它会重新下载所有 maven 依赖项，这在我的情况下意味着下载数百兆字节.

If I run it locally like this, I can see messages like Successfully extracted cache, but then it re-downloads all the maven dependencies, which in my case meaning downloading hundreds of megabytes.

我看不出本地运行和远程运行之间的区别，我猜它们的工作方式应该一样?

I cannot see the difference between running it locally and remotely, both of them should work the same I guess?

这个缓存存储在哪里?我可以以某种方式验证确实存储了一些东西吗?

Where is this cache stored? Can I somehow verify there is actually something stored?

推荐答案

如 这个问题，你需要将你的m2缓存文件夹放入一个卷中，否则容器每次都会从头开始(空缓存)，提示maven重新下载所有内容.

As in this issue, you need to put your m2 cache folder into a volume, or the container would start from scratch (empty cache) every time, promting maven to download everything all over again.

该问题也会报告，而不是使用卷:

That issue also reports, instead of using volumes:

如果您将 repo 指向 /cache 中的某些内容，则不需要指定 cache.paths 值；我当前实际使用的版本如下，我没有看到 .m2 的Removing.."行:

The cache.paths value doesn't need to be specified if you point the repo to something in /cache; the version I'm actually using currently is below, and I don't see the 'Removing..' line for .m2:

image:
  maven:3.3.9-jdk-8

variables:
  MAVEN_OPTS: -Dmaven.repo.local=/cache/maven.repository

test:
  script: "mvn test" 

但使用卷仍然是最便携的解决方案:

But using a volume remains the most portable solution:

我们编辑我们的配置以包含一个名为 host-cache 的本地 docker 主机卷，我们只需将上面的 /cache 引用替换为 /host-cache 不依赖于任何未记录的运行器默认值.

We edit our config to include a local docker host volume named host-cache, and we just replace /cache references above with /host-cache which doesn't depend on any undocumented runner defaults.

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