GPL3 project with EPL library

Question

I am making an opensource project and I would like to cover it with the GPL3 license. I also plan to use a library that is released under EPL license (https://github.com/forge/roaster). Is this possible?

More details: source code of my project and its resources would be covered with GPL3 license, but I would also like to include this EPL licensed library and some libraries under Apache 2 license and one library with BSD 3 license.

Answer 1

The GNU Project lists the EPL as a GPL-incompatible license which means that you cannot take EPL-licensed code and combine it in the same work as a GPL-licensed work.

However, since you are the author of the GPL work in question, you may license your work under the GPLv3 with exceptions. Section 7 of the GPLv3 allows you, the author, to introduce additional permissions, including the permission to link to specific libraries under GPL-incompatible licenses. The GPL FAQ has a tutorial on how to do this in a legally sound way. Therefore, you may include the EPL in your work licensed under the GPLv3-with-exceptions, and others may use, modify, and redistribute it without fear of legal complications.

Two important caveats about GPL exceptions:

• Per a comment below, the GPL-with-exceptions license you create by this process is itself incompatible with the regular GPL. This means that you cannot include anyone else's GPL code (nor can anyone else's GPL project include your code), unless the author of that code includes an identical exception to match yours.
• Any downstream recipient who modifies your code is free to remove the exception, at the cost of reintroducing incompatibility with the EPL component, but with the potential benefit of making the code compatible with the vanilla GPL.