#git-subtree

Fixed How do you merge two git repositories? #dev #it #asnwer

How do you merge two git repositories?

Consider the following scenario: I have developed small experimental project A in its own git repo. It has now matured, and I’d like A to be part of larger project B, which has its own big repository. I’d now like to add A as a subdirectory of B.

How do I merge A into B, without losing history on any side?

Answer: How do you merge two git repositories?

You…

Fixed Detach subdirectory into separate Git repository #dev #it #asnwer

Detach subdirectory into separate Git repository

I have a Git repository which contains a number of subdirectories. Now I have found that one of the subdirectories is unrelated to the other and should be detached to a separate repository.

How can I do this while keeping the history of the files within the subdirectory?

I guess I could make a clone and remove the unwanted parts of each clone, but…

How to: How do you merge two git repositories?

How do you merge two git repositories?

Consider the following scenario: I have developed small experimental project A in its own git repo. It has now matured, and I’d like A to be part of larger project B, which has its own big repository. I’d now like to add A as a subdirectory of B.

How do I merge A into B, without losing history on any side?

Answer: How do you merge two git repositories?

You…

How to: Detach subdirectory into separate Git repository

Detach subdirectory into separate Git repository

I have a Git repository which contains a number of subdirectories. Now I have found that one of the subdirectories is unrelated to the other and should be detached to a separate repository.

How can I do this while keeping the history of the files within the subdirectory?

I guess I could make a clone and remove the unwanted parts of each clone, but…

引言

git subtree命令是在git之上，用shell脚本编写的一个子命令。 与git submodule相比，它提供了更方便的子仓库管理； 与filter-branch相比，它确保了每次检出节点的一致性。

原则上，git subtree应该是一个很流畅透明的使用流程， 但是因为我们有过squash/no-squash混用，加之push --force的行为， 在没有理解git subtree实现原理之前，一度给我们带来很大的困惑。

接下来我先将subtree命令做简单剖析，再分析我们项目中的错误使用，望读者对git subtree能有更深入的理解。

更新本地命令 merge/pull

pull本质上也是fetch + merge。 在squash下，merge会查找最近一次squash节点，并在此基础上做squash。

推送远端 split/push

push的本质是split新历史并推送到指定远端的分支。 注意：split接受的参数不能直接传递给push，所以遇到特殊需求，先手动split -b吧。

参数

squash （no-squash）

在引入时将多个commits压缩为一个

squash commit message:

Squashed 'prefix/dir' changes from 69bd276..da8167e da8167e msg... dfafdae msg2... ... 69bd276 msgN... git-subtree-dir: prefix/dir git-subtree-split: da8167ea0ad433f5abb102d12b4bb78e9f823fe3

建议不要混用squash/no-squash，从一而终。 这个commit的message也是十分重要的，应为merge的时候会查找检验。

rejoin (no-rejoin)

将子仓库的历史切分出来后，使用git merge -s ours将新的节点更新至当前分支信息。 这样，merge命令可以很快的定位上一次节点，做增量的更新。

rejoin commit message:

Split 'prefix/dir' into commit '511145b80ecbdf471cbe0371a1619909a1e6a3a2' git-subtree-dir: prefix/dir git-subtree-mainline: 0b28ce2dbd843caf1b5cd5623b427ed6a17cca33 git-subtree-split: 511145b80ecbdf471cbe0371a1619909a1e6a3a2

ignore-joins (no-ignore-joins)

忽略上面squash/rejoin提交的节点信息，使用当前主仓库所有的历史信息，重做subtree的历史。

问题

在某一次squash后，我们强推了我们的子仓库代码，导致历史不一致，无法push.

git subtree push --prefix prefix/dir sub-remote maseter

经典的错误提示： fatal: bad object da8167ea0ad433f5abb102d12b4bb78e9f823fe3

git log --grep da8167ea0ad433f5abb102d12b4bb78e9f823fe3查找到出错的commit:

commit 8c8bfb0ffb6475c0e23a9b4aac803ccaf0f3e235 Squashed 'prefix/dir' changes from 69bd276..da8167e ... git-subtree-split: da8167ea0ad433f5abb102d12b4bb78e9f823fe3

是我们的某一个squash节点。

之前的解决方案（每次推到远端都需要如此）：

git subtree split --prefix prefix/dir 8c8bfb0ffb6475c0e23a9b4aac803ccaf0f3e235.. -b new-sub-tree git push sub-remote new-sub-tree:master

现在的解决方案（之后可正常subtree push）:

git subtree split --prefix prefix/dir -b new-sub-tree --ignore-joins --rejoin git push sub-remote new-sub-tree:master

Happy Coding!

Today I was needing to split a git repo into multiple repositories without loosing the commit history.

After searching a little bit, I have found git subtree and it was fairly easy to do it.