- Am I correct in thinking that if a service has properly configured timeout-kill and timeout-finish, timeout-down becomes unnecessary and even undesirable as it can leave services in an undefined state limbo? I know the documentation pretty much says so, but I'm still a bit confused by the existence of timeout-down to begin with, if it's redundant and unhelpful.
timeout-kill and timeout-finish are a s6 thing: if present, they're just copied as is to the service directory that will be managed by the s6 supervision tree. timeout-up and timeout-down are specific to s6-rc: they will be embedded into the compile database. They do not interact with s6 at all, they're just a rule for the s6-rc state machine: if the service does not report being up (resp. down) by the timeout, then s6-rc marks the transition as failed and stops looking at what happens with the service. For longruns, yes, timeout-kill ensures that the service will eventually be brought down no matter what. But there are cases where you *do not want* to kill -9 a daemon (and need a timeout-kill of 0). timeout-down is useful here, even if it's a pretty niche case. And then, of course, the point is that it's needed for oneshots, which do not have the s6 mechanisms.
- Can you confirm that timeout-up and timeout-down are also used with oneshots? They are defined in the s6-rc-compile documentation, but the s6-rc documentation doesn't specifically mention them for oneshots state transitions.
Yes, I confirm that they're also (and primarily) used with oneshots. They're defined in the "atomic services" section, which comprises longruns *and* oneshots. -- Laurent