Preserving History When Moving Files in Git

The What

I recently decided that I needed to move a directory from one Git repository to another where it would be a better, long-term fit. I'd never had any luck with this before (in the same repository, no less) so, like any intrepid developer, I took to Google to see if it was even possible. As it turns out, this has been an issue for many people over many years and there are a myriad of opinions on how to accomplish it.

Having read through more Stack Overflow threads than I'd like to admit, I decided that I'd write about what I did because:

It worked(!) and
It will be here to remind me the next time I need it.

The How

I followed a promising-looking reference to a blog post by Carlos Alberto Lopez Perez from all the way back in 2012. I've posted an adapted version of his process in the gist included below.

I also saw several examples that talked about using a git filter-repo command. If you're like me and didn't know that it isn't a native git command until entering it on the command line, surprise! It turns out that this is a plugin script. See the installation page in the project repository for information on how to get it for your platform.

TL;DR

OK, enough preamble. Here's the process I followed:

mkdir ~/dirswap && cd ~/dirswap
git clone repo1.git && cd repo1
# My use case: repo1/chart -> repo2/appname (mv < migration)
mv chart appname
git commit -am "chore: migrating helm chart to charts repo"
git filter-repo --path-rename chart/:appname/ --force
mkdir /tmp/mergepatches
export REPOSRC=appname    # (or srcfile.go if moving a file)
git format-patch -o /tmp/mergepatches $(git log $REPOSRC|grep ^commit|tail -1|awk '{print $2}')^..HEAD $REPOSRC
cd ~/dirswap
git clone repo2.git && cd repo2
git am /tmp/mergepatches/*.patch

The Bottom Line

While I won't pretend to know if this truly represents the real history of the files, I like this solution in that I don't have to use git log --follow to see the history. Plus, I'm lazy and would rather use GitHub's UI to display the history (which would not be possible without editing the commits).