Suppose I have a repo parent and a repo child, where the latest is a submodule of the first one.
My child repo is being maintained by a third party. I would like to keep track of the most recent updates made by this third-party while also doing my own specific changes to this submodule to make it compatible with my parent repo.
What is the proper way to do this?
This may not be the most elegant way to use submodules, but I have this exact situation and I handle it by cd-ing into the submodule and handling it from there as a classic Git repo.
This way, it is easy to set my own fork of the child project as origin and the original child project as upstream. I can pull from upstream to get the latest updates from the original project (maintained by a third party), make my own changes and push them to origin so that they can be shared.
To update the parent repo, I simply stage and commit the changes to the submodule.
In order to know what changes were made to the submodule from the parent project when I commit those changes, I have, in my git config file:
[diff]
submodule = log
This will show the log of the submodule when running diff operations from within the parent project. It is not necessary, but it is convenient as I don't have to go down to the submodule to know what I have done, etc.
You can set this locally by running git config diff.submodule log from your parent repo or you can set it globally with git config --global diff.submodule log.
Note that you get the same result by running git diff --submodule from your parent repo instead of git diff (if you don't want to play with your config files).