I have a web application that explores other web applications in a particular way. It contains some web demos in a demos
folder and one of the demo should now have it's own repository. I would like to create a separate repository for this demo application and make it a subpackage submodule from main repository without losing its commit history.
Is it possible to keep the commit history from the files in a repository's folder and create a repository from it and use it as a submodule instead?
See the note at the end of this answer (last paragraph) for a quick alternative to git submodules using npm ;)
In the following answer, you will know how to extract a folder from a repository and make a git repository from it and then including it as a submodule instead of a folder.
Inspired from Gerg Bayer's article Moving Files from one Git Repository to Another, Preserving History
At the beginning, we have something like this:
<git repository A>
someFolders
someFiles
someLib <-- we want this to be a new repo and a git submodule!
some files
In the steps below, I will refer this someLib
as <directory 1>
.
At the end, we will have something like this:
<git repository A>
someFolders
someFiles
@submodule --> <git repository B>
<git repository B>
someFolders
someFiles
Get a fresh copy of the repository to split.
git clone <git repository A url>
cd <git repository A directory>
The current folder will be the new repository, so remove the current remote.
git remote rm origin
Extract history of the desired folder and commit it
git filter-branch --subdirectory-filter <directory 1> -- --all
You should now have a git repository with the files from directory 1
in your repo's root with all related commit history.
Create your online repository and push your new repository!
git remote add origin <git repository B url>
git push
You may need to set the upstream
branch for your first push
git push --set-upstream origin master
<git repository A>
(optional, see comments)We want to delete traces (files and commit history) of <git repository B>
from <git repository A>
so history for this folder is only there once.
This is based on Removing sensitive data from github.
Go to a new folder and
git clone <git repository A url>
cd <git repository A directory>
git filter-branch --force --index-filter 'git rm --cached --ignore-unmatch <directory 1> -r' --prune-empty --tag-name-filter cat -- --all
Replace <directory 1>
by the folder you want to remove. -r
will do it recursively inside the specified directory :). Now push to origin/master
with --force
git push origin master --force
Create a submodule from <git repository B>
into <git repository A>
git submodule add <git repository B url>
git submodule update
git commit
Verify if everything worked as expected and push
git push origin master
After doing all of this, I realized in my case that it was more appropriate to use npm to manage my own dependencies instead. We can specify git urls and versions, see the package.json git urls as dependencies.
If you do it this way, the repository you want to use as a requirement must be an npm module so it must contain a package.json
file or you'll get this error: Error: ENOENT, open 'tmp.tgz-unpack/package.json'
.
You may find it easier to use npm and manage dependencies with git urls:
npm init
inside both repositoriesnpm install --save git://github.com/user/project.git#commit-ish
where you want your dependencies installed