如何为Docker Cloud在Dockerfile中正确初始化git子模块

Question

我们正在Docker Cloud上构建一个Docker容器。构建过程需要git子模块。

要为本地构建初始化子模块，我们将以下行添加到了Dockerfile中：

RUN git submodule update --init --recursive

请参阅：https://github.com/open62541/open62541/blob/master/Dockerfile#L9

相应的提交：https://github.com/open62541/open62541/commit/ee9c18a6a05722edfe7c0d8d8e140d802fa2e5f2和拉取请求：https://github.com/open62541/open62541/pull/3191

注意：与类似的问题相反，所有子模块都是github上的公共存储库，无需身份验证。

没有子模块初始化行的情况：

• 基于Docker Cloud构建：成功https://cloud.docker.com/u/open62541/repository/registry-1.docker.io/open62541/open62541/builds/dcd3283c-76af-4f6b-bb00-cecbaaffc82f
• 本地构建：失败

git clone https://github.com/open62541/open62541.git
cd open62541
# Parent commit without git submodule update
git checkout e97abd591a159ce894488d93796b858d9f0d00b9
# This will fail because the submodules are obviously not initialized
docker build .

错误：

CMake Error at CMakeLists.txt:830 (message):
  File /opt/open62541/deps/ua-nodeset/Schema/Opc.Ua.NodeSet2.xml not found.
  You probably need to initialize the git submodule for deps/ua-nodeset.

Dockerfile中子模块初始化的情况：

• 在Docker Cloud上构建：失败https://cloud.docker.com/u/open62541/repository/registry-1.docker.io/open62541/open62541/builds/28663705-c324-4c7f-a084-f94eb80057bc

Step 7/18 : RUN git submodule update --init --recursive
---> Running in b358c21c4d53
fatal: not a git repository: /src/b6tohshrfzzntavvhek3zna/.git/modules/deps/mdnsd
Unable to find current revision in submodule path 'deps/mdnsd'

• 在本地构建：成功

git clone https://github.com/open62541/open62541.git
cd open62541
# Commit which added git submodule init in Dockerfile
git checkout ee9c18a6a05722edfe7c0d8d8e140d802fa2e5f2
# This will succeed
docker build .

如何正确初始化dockerfile中的子模块，以便它可以在Docker云上运行，同时可以只提取主存储库并构建docker容器？

---

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Answer 1

请参阅我在此处给出的答案：https://stackoverflow.com/a/59640438/1021344

为简单起见，在此复制：您需要使用钩子：https://docs.docker.com/docker-hub/builds/advanced/#custom-build-phase-hooks

TL; DR：将此放置在hooks/post_checkout：]中>

#!/bin/bash
# Docker hub does a recursive clone, then checks the branch out,
# so when a PR adds a submodule (or updates it), it fails.
git submodule update --init