Three days ago the Ubuntu Community Council released this document about the downstream distro agreement Canonical provides.
This is one of the worst documents i have seen released by the Council ever, it explains exactly nothing but tells you “Canonical is doing it right, trust them, we do too”. There is not a single piece of the technical background behind all this explained anywhere (while there is a lot to explain and if people read it they might even grasp why this agreement exists) or why it has nothing to do with licensing the ownership of anything to anyone, claiming debian copyrights, violating the GPL or any other such rubbish that gets claimed all around the net now. In this specific case i feel the Council has not done their homework … and why … oh why .. did you guys even have to put the word License into your headline at all. While the word might have some meaning to lawyers in this context, it must have been clear to you that this word will blow everything out of proportion .. the emphasis here needs to be that it is an agreement between both sides to protect the Mint users from technical breakage of their system …
So lets see if a proper technical explanation can probably calm the tempers a bit …
We’ll have to do some time travelling for this … come back with me to the year 2004 when a small developer team of less than 20 people grabbed the giant debian archive, made some changes to it, recompiled the whole thing and released it under the name Ubuntu.
Back then people read everywhere that this Ubuntu thing is based on debian and indeed when they found some third party packages built for debian (and not Ubuntu) they could sometimes even install them without breaking their system. Some people even went further and actually added debian repositories to their sources.list and were surprised to see their systems go up in flames.
Ubuntu packages aren’t at all the same as debian packages, Ubuntu might have made changes to some UI library where a binary symbol that offers the “draw rectangle” function actually draws an oval on your screen. Binary packages that were recompiled against this lib in the Ubuntu archive know about this change, binary packages from the debian archive that have been compiled against the debian version of the library will not know that, once they try to use the “draw rectangle” function, something unpredictable happens and the app falls over.
Today it is a known fact to most that you should not simply add a debian repo to your package sources, the info has spread across the net after 10 years, the generally established support answer if someone asks about adding plain debian binaries is “yes, you can and if you are lucky it even works, but if it breaks you have to keep both pieces”. The fact of binary incompatibility has caused lots of discussions and some anger on the debian side back then. “Why can’t you just do your work in the debian archive” was a question i remember hearing often from DDs back then. Ubuntu wanted to do stuff faster than debian and move ahead with some pieces. Debian is a rock solid tanker, it is gigantically big like a tanker but it is also as slow as one. Imagine that without Ubuntu doing this step things like developing upstart would not have been possible, imagine also that without Ubuntu moving forward with upstart and changing the init system there would most likely be no systemd today. Sometimes you need to move out of boundaries to get the whole thing to the next level.
Now lets fast forward back into presence again. Ubuntu has grown over ten years and there are many “in-archive” and also many “out-of-archive” downstream distros. It is facing something similar debian had to face back then. Downstream distros start to make changes out of the archive and provide their own binary packages for some bits. There is no problem at all with distros like Kubuntu, Xubuntu or Lubuntu here, their changes happen inside the Ubuntu archive packages in the archive will be linked against i.e. Kubuntu library changes. If it comes to the “out-of-archive” downstream distros there can indeed be the exact same problem that Ubuntu faced with debian back in 2004. These “out-of-archive” distros want to innovate the code, user experience or system design in a way that is either not appropriate for them to contribute back, or not appropriate for Ubuntu to take said contribution (because it breaks some existing functionality in Ubuntu or whatever). They feel they need to do their changes outside of the archive like Ubuntu felt back then with debian. Sadly these downstreams often enough do not have the resources to actually rebuild the whole archive so they start providing a mishmash of their re-done binary packages with the binaries from the Ubuntu archive which will leave you as a user with the same situation the early Ubuntu users.
For Mint you can find the list of changed packages on this page … you will see that for example libgtk is in the list, in case Mint decides to switch the “draw rectangle” function to actually draw triangles without bumping the ABI all Gtk apps that you use directly from the Ubuntu archive will possibly fall flat on their face. Users will be upset and blame either the bad Mint or the bad Ubuntu quality for their breakage. Now imagine what would happen if Mint decides to make any innovation of libc (like Valves SteamOS does very heavily with regard to debians libc), the library everything is linked against either directly or indirectly. Most likely the majority of original Ubuntu packages would just break and they would be limited to only use the packages listed in that linked document.
Lets do a short detour towards Trademarks now … Canonical owns the Ubuntu trademark, this means two things … one is Canonical can make money from it (yay, that luckily pays my salary so i can do paid work on my favorite OS all day !!!) … but that part is not involved in this agreement at all, nobody is asking Mint to pay anything. The agreement also does not mean that Canonical claims any ownership of any code from debian, violates the GPL or steals credit for any of the code in the Ubuntu archive.
Remember, I said owning the Trademark means two things … the second thing is that Ubuntu means a certain quality (be it good or bad is up to the beholder here, feel free to make your own judgement). If i install Ubuntu i can expect a certain level of quality and that the basic desktop largely works (yes, yes, i know there are enough bugs to make a lot of jokes over that statement). It also means that distros claiming to be “based on Ubuntu” inherit that archive quality of the binary packages. You can rely on the fact that the Kubuntu installer is using the same back ends and libs the Ubuntu installer uses for example. Bugs on the low level are shared and fixed for both. Now lets look back at the list of Mint packages and we will see that they provide their own “Ubiquity” package. I don’t know what changes are in there and I don’t know if it does not make the Mint installer completely incompatible to what Ubuntu, Xubuntu, Edubuntu or Lubuntu use, it will likely introduce different bugs and features into the binary resulting from that source. So this second part of owning the Trademark is about protecting the brand by guaranteeing a certain quality under this brand (which in turn indeed helps for the first part).
While the agreement with Mint kind of targets the second part here, it protects the reputation of Mint more than it does protect the Ubuntu reputation. It makes sure that Mint users will not have false expectations and that their systems will not suffer from technical breakage by Mint claiming it is 100% Ubuntu binary compatible … And while this whole agreement might technically be treated as License in front of a court (where it most likely will never go) IMHO the bigger info here is that there is an agreement between two distros to prevent Mint users from the same issues Ubuntu users faced back in 2004 with regards to debian. If this makes Canonical evil is up to you to judge, I personally think it does not and is a good thing for both sides in the end.
Please note that all the above is my personal opinion and should in no way be quoted as Canonical statement, I solely write all this as an Ubuntu developer independently of my employer (I would have written the same if i would work at Google and do Ubuntu development in my spare time). In case you want to re-share it on your news site, please get this differentiation straight !