> I'd draw a fine line between real application level debugging which should never happen on production and ops tooling
Sorry, but that's just plain wrong. One very common reason why people do that is, because performance debugging may give very different results on dev, staging and production systems that's why people want tooling that gives them as accurate as possible application level debugging information without impeding the behavior of the system. It's a very common problem in large scale systems.
I think that can be solved by good tracing and logging facilities. Both of which are already available in Linux (eBPF, ftrace, tracepoints, perf events...). You may have to customize them or polish them further though and provide more user friendly interfaces/frontends for them.
Maybe. But KGDB and friends do exist too in Linux. And (AFAIK) not everyone likes using those, some just like throwing a few printks here and there. That is not universal obviously :) My point is that yes, unikernels may not be as easy to debug etc at this point as regular usermode code, but it is something that can be worked around and I think if people begin to use them in-mass frameworks and solutions will emerge.
Sorry, but that's just plain wrong. One very common reason why people do that is, because performance debugging may give very different results on dev, staging and production systems that's why people want tooling that gives them as accurate as possible application level debugging information without impeding the behavior of the system. It's a very common problem in large scale systems.