Is there a way to use a Mercurial repository as Git submodule?

Question

I been happily using submodules to track all the libraries my project depends from. The thing is I'm using a library called core-plot that only has a public mercurial repository. I can probably mirror it in a readonly Git repository, but is this the best option I got? I had seen there is modules in Mercurial to track things in Git. Someone know if the other way around exists?

It may be simplest to just put the whole checked out mercurial repository under git version control. That way you can update the library via hg whenever you want and still have it under git source control in your project. — Clemens
The problem with that is you are downloading it when you clone the main repository while submodules are fetched on demand. — dvicino
Lol, then you create a new git repository and put the whole mercurial stuff in. This git repo can be used as regular git submodule.. problem solved — Clemens
That what mirroring means, also you can add a hook to your git mirror to fetch from the hg before replying, just was checking if someone had any solution that didn't need a server mirroring. — dvicino

Jim DeLaHunt Jim DeLaHunt · Accepted Answer · 2012-02-01T17:42:53

Using git-hg.

First, make sure there is a (non-Mercurial) git submodule under your main repository. If you don't have other submodules yet, just create a dummy submodule for some library other than core-plot, for instance:

main-repo $ git submodule add https://repo.url.com/repo.git repo

Second, clone the core-plot library into some directory.

main-repo $ git-hg clone  https://code.google.com/p/core-plot/ core-plot

Add the new repo to the submodule list.

main-repo $ git submodule add ./core-plot core-plot
main-repo $ git commit -am "added core-plot submodule"

From now on, any clone from this repo will pull both repositories. (After submodule init and update).

Some problems I found out so far are:

If you push to a bare, then the repo link and the directory will be created in the bare, but the repository will not be cloned inside it and others pulling from that bare will not be able to get the core-plot lib.
If core-plot needs to be updated the one with the git-hg will have to git-hg pull.

The converse question git submodule from Hg repo? is also asked on StackOverflow. The best answer mentions projects hg-git and git-hg. Another related converse question is, How to deal with Git submodules on a repo that is converted to Mercurial.

Is there a way to use a Mercurial repository as Git submodule?

2 Answers