What is HomeAssistant OS doing?

… this is a question I am asking so often.

These many layers of OS, supervisor, docker, add-ons make it so opaque what’s really happening under the hood.

Starting the system takes like 5-10 minutes and during that time I cannot reach anything. Yet, the CLI is fully functional. But I don’t know what to do with it.

I have no clue what takes so long to start, it’s completely unclear which process/add-on/step/container is blocking something and why.

So, my question is: How can I, with the help of the CLI, get insight into what’s happening right now? Which add-ons are running and in which state are they? Is anything blocking or failing? Which container/add-on/part uses lots of CPU?

After home assistant has started, go to Settings → System → Repairs → three dot icon top right → Integration start up times. This might throw some light on what is taking so long.

Home Assistant OS is the equivalent of Windows.
Home Assistant core (the actual HA you see) is the application, which in the Windows world could be something like Word or the game you might be playing.

Thanks, that’s a good pointer. But the times here are somewhat small/reasonable. Boot may take waaay longer.

My question is actually more general than that: Sometimes, it just takes so long and I can’t reach HA. I am also using the nginx proxy add-on, so maybe it takes much longer for this up and running than HA itself. So my question is, how can I debug when this happens? How can I figure out where it’s stuck or maybe if the whole thing is stuck and I should just do a hard reset? How can I check which add-ons are loaded, what add-ons or HA itself is doing (something like “tail -f /progress.log”) etc. I tried “top” in that situation but it doesn’t really show anything insightful.

If you connect a monitor to the HA server, then you can see when HAOS is up, which should be pretty fast.
HA core starts afte the HAOS and some integrations can take a while to start.
The guide tom_l gave you should help you there as well as looking into the logs for supervisor and HA core.