Working with multiple remotes in Git

goal

I want to push the same project to multiple git forges.

• one remote per git forge: codeberg, sleeping, tangled, maybe even github, etc
• a remote called all where git push all pushes to all the remotes

beforehand

You’ll need your git committer email address to be something all of the Git forges accept.

Generally this means you can’t use, say, github noreply faux-emails.

on remotes

Basically:

• Git remotes can have more than one push URL.
• There’s no rule against two different remotes sharing the same push URL.
• Git remotes can specify different URLs for fetching and pushing.

If you want to use multiple git forges, merging everything into a single mega-remote isn’t the best solution, since you usually want to pull from just one (checking out a contributor’s branch, manually syncing things back up, etc)

Being able to specify different fetch/push URLs is sort of a newer git feature I think. By default a remote contains one url which is used for fetching and pushing. You may also specify some pushUrls which will be used instead of url for pushing. The url option is mandatory, so all remotes have a fetch URL whether you want it or not. If you don’t want a fetch URL, something like file:///dev/null or https://google.com will satisfy the config schema but won’t actually work.

Commands

• git remote add <name> <url> to add a remote, as usual

• git remote set-url --add <name> <url> to add a new fetch URL (pulling)

  • add --push to add a push url

getting familiar with .git/config

After git remote add remoteone http://google.com:

[remote "remoteone"]
    url = http://google.com
    fetch = +refs/heads/*:refs/remotes/remoteone/*

google.com is currently the fetch and push URL of this remote.

fetch is a “refspec”, documented here.

• I don’t know what the + prefix means.
• Before the colon is refs/heads/* and after the colon is refs/remotes/remoteone/*. This defines a mapping between my local branches (in refs/heads/) and branches fetched from the remote (which would go in refs/remotes/remoteone/… if this was a real git remote)

After git remote -u remoteone/trunk (setting the upstream branch of trunk to remoteone/trunk)

[remote "remoteone"]
    url = http://google.com
    fetch = +refs/heads/*:refs/remotes/remoteone/*
[branch "trunk"]
    remote = remoteone
    merge = refs/heads/trunk

Branch “trunk” remote is documented here, merge is documented a few lines below.

(since google.com is not actually a git remote, this needed a plumbing command described below)

trying this on a real project

Here’s a project I’ve had set up for a while. It’s on github :pensive:

[remote "origin"]
    url = https://github.com/quat1024/mods
    fetch = +refs/heads/*:refs/remotes/origin/*
[branch "trunk"]
    remote = origin
    merge = refs/heads/trunk

Let’s start mirroring this to codeberg or something.

First i’ll rename the remote from origin to github with git remote rename origin github. Now the file looks like this.

[remote "github"]
    url = https://github.com/quat1024/mods
    fetch = +refs/heads/*:refs/remotes/github/*
[branch "trunk"]
    remote = github
    merge = refs/heads/trunk

and several refs have been updated on my local repo.

Next i’ll log into codeberg and create a new repository through the interface, then git remote add codeberg <url>.

[remote "github"]
    url = https://github.com/quat1024/mods
    fetch = +refs/heads/*:refs/remotes/github/*
[branch "trunk"]
    remote = github
    merge = refs/heads/trunk
[remote "codeberg"]
    url = https://codeberg.org/quat/mods.git
    fetch = +refs/heads/*:refs/remotes/codeberg/*

So trunk is still doing remote-tracking stuff from github. I guess I have to pick one?

Can push to codeberg with git push codeberg. Nice.

Did the same thing with tangled. Can push to tangled with git push tangled. Nice.

Clean this up: git remote remove github. This also removed the [branch "trunk"] section since it doesn’t know its remote-tracking branch.

making an all remote

Make the remote with a bogus fetch URL and add two push URLs to it.

git remote add all file:///dev/null
git remote set-url --add --push all "ssh://git@codeberg.org/quat/mods.git"
git remote set-url --add --push all "git@tangled.sh:highlysuspect.agency/mods"

[remote "codeberg"]
    url = ssh://git@codeberg.org/quat/mods.git
    fetch = +refs/heads/*:refs/remotes/codeberg/*
[remote "tangled"]
    url = git@tangled.sh:highlysuspect.agency/mods
    fetch = +refs/heads/*:refs/remotes/tangled/*
[remote "all"]
    url = file:///dev/null
    fetch = +refs/heads/*:refs/remotes/all/*
    pushurl = ssh://git@codeberg.org/quat/mods.git
    pushurl = git@tangled.sh:highlysuspect.agency/mods

Moment of truth:

quat@moon:~/dev/mc/mods$ git push -u all trunk
branch 'trunk' set up to track 'all/trunk'.
Everything up-to-date
Welcome to Tangled's hosted knot! 🧶
branch 'trunk' set up to track 'all/trunk'.
Everything up-to-date

Nice. Now my git config has this in it:

[branch "trunk"]
    remote = all
    merge = refs/heads/trunk

other commands i learned

i knew about git push -u <remote> <branch> which does two things

1. sets <remote> as the “upstream” for branch <branch> (locally)
2. pushes the branch to the remote (which creates the corresponding branch on the remote)

i didn’t know about git branch -u <remote>/<branch>, which only does the first one, iff the branch already exists on the remote. (specifically, the necessary condition is that your local git has to know about the remote’s branch, which may require a git fetch <remote> to refresh things)

there is a way to manually tell git yes, don’t worry kitten, there is a branch on that remote – but i really doubt it’d work on real git remotes

# do not use this
git update-ref refs/remotes/<remote>/<branch> HEAD