GitHub provides mirrors of Eclipse projects.
GitHub populates the mirrors from a script that generates a list of repositories from project metadata:
Only valid Git repositories specified in the "source repositories" metadata field will be replicated.
The script is run manually on a periodic basis. We nudge GitHub every once-in-a-while (monthly or so) to run the script and update the mirrors. If your repository has not been mirrored, open a bug against Eclipse Foundation/Community/Git to ask us to initiate a nudge. Do not expect us to badger the nice folks at GitHub daily or in a piecemeal manner. We won't do it.
There is really very little for you to do to make this mirroring happen. Every repository under
/gitroot/ (with the exception of website repositories found under
/gitroot/www.eclipse.org) is included by our script.
If you actually want to push and pull into a GitHub repository, we'll need to make a team for your project. Open a bug against Community/Git and we'll help you out. Note that we can set up a GitHub team and can make changes here and there, but we are unable to automatically mirror changes in the project committers at this time.
The GitHub mirror is not strictly subject to the same access restrictions as the eclipse.org repositories. The Eclipse Foundation considers the GitHub teams to be self-regulating. We will help where we can, but the GitHub mirrors are not considered to be eclipse.org property. If there are problems within the teams, they can be addressed by the Eclipse Organization's GitHub administrators (one of whom is conveniently a member of the Eclipse Foundation staff).
For Eclipse projects, the Git repository on eclipse.org must be considered the "central" or "main" repository for the project code. Contributions can be accepted into the GitHub mirror, but anything that flows back into the equivalent eclipse.org repository is subject to the Eclipse IP Due Diligence Process.