alt Hacker NewsEven for those who do this right, some things change under your feet because OSS maintainers of kernel feature A want to stop supporting V1 of A when V2 has been out for a decade. But the features missing in V2 are supposed to be provided by userspace B - and they are yet to tackle the functionality altogether. So now your app will just have to regress in features. It is very easy to ship OSS code as a maintainer of a project, it is very difficult to keep up with Linux as a developer unless you stick to libc. There is no one source of truth with regards to how things should work, there is no one roadmap, and maintainers care a lot more about complexity than maintaining feature parity of backwards compatibility. I do not blame them, but then it is difficult to target linux. Much easier to support a platform with guarantees and a shared vision. Saying this as someone who has only used Linux at home for 20 years.
Thanks to the Linux kernel's extremely high backward compatibility, and virtually all the libraries being open source, you can ship old or frozen versions of libraries with your application if you have to. You can defensively set shipped binaries as fallbacks in the event the application is running on a newer system that dropped critical functionality, while using the distro version if that's more up to date and still has the functionality. You can do the same for auxiliary programs your application uses.
I agree that sticking to libc is most reliable, if you can. But the experience is poor if you do that for desktop applications.
There's no singular source of truth, but there's a de facto frontier of only a few mainstream distros, as well as upstream heads for your dependencies.
It's extra work, but there are systematic workarounds to the feature drift over time and the tendancy of some open source projects to aggressively deprecate older functionality and older system compatilbilty.
You can, to an extent, automate testing on newer versions of distros to be alerted when something no longer works, and often you can do this before the official distro release date.
Unfortunately even libc is not reliable. Unless it's a static build, Glibc is often broken (with symbol version errors) when trying to run a binary compiled on one distro on another distro, or an older version of the same distro. Static binaries have other problems, though work very well if the application is self contained and isn't a GUI.
One thing that I find works very compatibly, though, is OpenGL / Vulkan binary-compatibility across distros and versions. There was a lot of work done on making libGL something you can link to or dynamically load reliably and take it from there. The OpenGL extension spaghetti is an interesting problem from then on, but that's more to do with the individual user's GPU and GPU drivers, independent of the Linux distro or even which OS it's running on.