The trick is to have a environment where you can take the complex apart and examine each part in isolation, and then bring them together until you replicate the

The trick is to have a environment where you can take the complex apart and examine each part in isolation, and then bring them together until you replicate the error. With older _nix setups that was fully possible because daemons were pretty much (i am likely to get dogpiled on this) a user process without a shell to send output to. With systemd on the other hand the state inside a systemd-managed unit, and the state outside of said "black box" may be wildly different. And to debug the person doing so have to attempt to maintain a massive mental image of state. Frankly the kernel may well be the closest approximation, and it may well be better instrumented at this point. Never mind that building a second kernel in userspace is not a kudos point.