#+date: <2025-04-05 Sat 23:04:54>
#+title: Mirroring my Repositories from GitHub to GitLab
#+description: Read to learn how I was able to efficiently make sure all of my repositories are mirrored from GitHub to GitLab.
#+filetags: :git:
#+slug: git-mirror

This is a short post detailing how I maintained repositories on GitHub and
mirrors on GitLab - including both public and private repositories.

Since GitLab locks pull-only mirrors behing their Premium and Ultimate tiers, I
found a different solution.

* Creating Mirrors

I'll skip the setup and just hit the bullet points:

- I have a plethora of GitHub repositories.
- I used GitLab's mass-import functionality to do the initial import of my
  repositories from GitHub.
- I made sure all of my GitHub repositories were cloned locally in my =~/git=
  directory.

* Setting up Mirror Connections

To start, I navigated to the =~/git= directory, which holds all of the
repositories I have on GitHub and created a shell script.

#+begin_src shell
cd ~/git
nano setup_mirrors.sh
#+end_src

Within this shell script, I created a loop that will open each repository and
add both the GitHub and GitLab SSH-style clone URIs to the =origin= remote.

#+begin_src shell
for repo in */
do
    cd $repo
    git remote set-url origin --push --add git@github.com:ccleberg/${repo%*/}.git
    git remote set-url origin --push --add git@gitlab.com:ccleberg/${repo%*/}.git
    git remote -v
    cd ..
done
#+end_src

Once complete, I created another shell script to open each repository, pull any
remote commits, and push local commits to both remotes.

#+begin_src shell
nano mirror.sh
#+end_src

#+begin_src shell
for repo in */;
do
    cd $repo
    git pull --rebase origin HEAD
    git push
    cd ..
done
#+end_src

Finally, enable execution of both scripts before moving on.

#+begin_src shell
chmod +x setup_mirrors.sh
chmod +x mirror.sh
#+end_src

* Initialize Mirrors

To use the =setup_mirrors.sh= script above, simply execute it from a terminal.

#+begin_src shell
./setup_mirrors.sh
#+end_src

Once complete, each repository /should/ have one fetch URI (GitHub) and two push
URIs (GitHub & GitLab). At this point, any =git pull= or =git fetch= commands
will pull from GitHub and any =git push= commands will send updates to both
GitHub and GitLab.

* Schedule Periodic Checks

To utilize the =mirror.sh= script from the previous step, let's use crontab.

#+begin_src shell
crontab -e
#+end_src

Within crontab, I used the schedule below to ensure the script is executed
daily.

#+begin_src text
0 0 * * * /Users/cmc/git/mirror.sh
#+end_src

This ensures that the =mirror.sh= file is executed daily and will push any local
or GitHub commits to GitLab.

I have tested this by manually running =mirror.sh= and watching the results.
There are edge cases where I will need to intervene and manually resolve merge
conflicts, but it's largely autonomous, so I'm happy with the results.