Minecraft is GPL
Minecraft is GPL🔗
I'm not a lawyer! This post is meant to be a fun history lesson and thought experiment, - or maybe a parable - around a complex licensing situation.
Preamble🔗
Bukkit was a very popular modded minecraft server licensed under GPLv3 and LGPL.
Throughout the first half of the 2010s it was the defacto standard minecraft server implementation in use, and its forks and api are still going strong today through projects like spigot, paper, and glowstone.
The Licensing Situation🔗
Bukkit was two projects, the API (licensed under GPLv3), and CraftBukkit (LGPL): a modded mincraft server wich exposed this API to enable making plugins.
If you know anything about Free Software licenses, you might be able to tell that this is already pretty problematic.
CraftBukkit - which depends on Bukkit is licenced under a more permissive license than Bukkit. Thus distributing CraftBukkit under the LGPL (as a whole) would be a violation of Bukkit's license.
Maybe this could be overlooked - I mean, it's the same project and no one contributing could be thinking their contributions weren't intended to end up in CraftBukkit. Besides in the worst case all that has to be done is for the whole to be released under GPLv3 - Something the LGPL generally allows.
Since the Bukkit API (and library) is GPLv3, techincally all plugins are probably also GPLv3?
Unfortunately CraftBukkit is more than just bukkit. The distribution is more like Bukkit (GPLv3)
- CraftBukkit (LGPL)
- Minecraft (Proprietary)
Not only does it link to Minecraft, it includes decompiled code, and most of it could definetly be construed as a derivative work of it.
This makes the distribution itself a straight copyright violation.
That would be that, and the argument is that CraftBukkit not being able to be released under the GPLv3 voids the license.
All authors have copyright for their contributions and have never had license from any other contributor - Just like they didn't have a license for Minecraft.
Anyone could at will DMCA anyone. Which as you will see, is what happened in the end.
How did this happen?🔗
The bukkit project was so successfull that eventually their core developers were hired my Mojang - the owners of Minecraft, just two years after the project was started.
After this, three out of the four core developers stopped working on bukkit. The one that remained active in the bukkit project left Mojang 20 months later.
Unfortunately the CraftBukkit repository is not available due to a DMCA, therefore I can't link to a more busy repository.
It's clear that Mojang is very much aware of the copyright infringements taking place at this point, and are really enabling and directly endorsing it.
This made Mojang and the ex-bukkit developers spring into action. Here's a summary from the mojang developers themselves, including tweets from the lead developer "Jeb_".
They were suddenly revealing that when the bukkit developers were hired two years earlier, they also "bought bukkit", and would be updating it themselves, insisting the project was not shut down. And that bukkit had a "special relationship" with regards to the EULA
This surprised and angered a lot of people who were working under the assumption that bukkit was a community lead project and not beholden to Mojang (apart from the copyright violations looming over them at all times). Including one developer who decided to DMCA the project
And now for the epilogue, or rather, the punchline🔗
However, CraftBukkit was released, as a whole under the LGPL (really GPLv3), for 2.5 years while being owned by Mojang. It might be fair to say that the copyright holder of minecraft was the one releasing it. This is even suggested at with the "special relationship" according to Jeb_.
The only legal way for this to be done is for minecraft to be at least LGPL-compatible. Such that CraftBukkit could be released by Mojang (or at least their subsidiary) as GPLv3.
Mojang certainly had the rights to publish minecraft under an LGPL-compatible license. Bukkit's LGPL code can be linked to in a work licensed as GPLv3. Thus Minecraft Java Edition 1.2 to 1.7 is free software.
Unfortunately (contrary to horrifyingly common practice in the free software community) licenses don't really act automatically like this, the most restrictive license in the chain (plus whatever ownership the distributor actually has) isn't what actually counts.
Post Scriptum🔗
The most glaring hole in this logic is that more than likely Mojang "owning bukkit" was limited to the trademark, and maybe the contributions of the developers who joined Mojang.
Bukkit was an informal organization, not a legal entity, and even if it was, a subsidiary does not automatically get the rights to their parent's assets.
The way Mojang communicated during the situation is hard to decipher in regards to exactly what "owning bukkit" means. And the tweets of some employees (even high ranking ones) might not have that much legal sway
So it's entirely possible that bukkit - even during this timeframe - did not actually have the right to publish CraftBukkit under a theoretical GPLv3.