On Sun, 20 Sep 2015 18:41:15 +0200 Laurent Bercot <[email protected]> wrote:
> On 20/09/2015 18:26, Steve Litt wrote: > > > Of course, all this could be avoided the LittKit way and just run a > > script depositing "down" files before running the supervisor. But > > the LittKit way specifically defies Laurent's proposal that PID1 be > > able to restart the supervisor (I think). > > I don't know exactly how LittKit does things, but "depositing ./down > files" is the way s6-rc proceeds internally. It does not go against > the principle of the supervision tree being able to restart the > service, because only services that are supposed to be down have > a ./down file. I spoze you're right. If PID1 can restart rc.supervise, and rc.supervise deposits down files and then exec's the supervisor, it fulfills your requirements. > The state where everything is down is temporary, at > start; then the service manager removes ./down files one by one as it > brings up the services. What you describe is pretty much how LittKit operates, except with LittKit there must be one service directory not containing a down file, or nothing will operate: In other words, the initial service (which is a oneshot) removes the down files in a specific order, as well as inserting any necessary delays, and IIRC on one occasion actually looping while a specific service became responsive. > > PID 1 being able to restart the supervisor is something else: it's > the reason why I disagree with your choice of suckless init. You and I have different use cases, which causes me to prioritize PID1 respawning supervision much less than you prioritize it. If my desktop computer terminated into a kernel panic of just became totally unresponsive, I'd power it off, power it back on, and fsck. However, if I were running an airline reservation system on my computer, I wouldn't be so cavalier in dismissing the destruction wrought by everything except PID1 terminating. In other words, for heavy industrial work, I'd use s6 and leave Suckless-Init behind. SteveT Steve Litt August 2015 featured book: Troubleshooting: Just the Facts http://www.troubleshooters.com/tjust
