[Box-Admins] daemontools versus systemd [was: source.squeak.org went down today]

[Levente Uzonyi]

IMHO daemontools does what it offers, it supervises processes. In case 
of the source.squeak.org the image was up and running, but 
it was non-functional.
Daemontools is not a system monitoring tool; it won't check the health of 
the services, it'll simply ensure that the processes are running.
On the new boxes we can consider using monitoring tools.

Levente

On Tue, 21 Oct 2014, Chris Cunnington wrote:

> Just on the topic, I find daemontools confounding. The svc tool is supposed to start and stop processes, but I also find it doesn’t work. As I understand it, svc is supposed to control a supervise process,
> which overlooks a process like source.squeak.org. But how does that start exactly? I think there’s more than one way. I think creating a symlink to to the /service directory is supposed to do it. I’ve also
> used something like “supervise foo&”, which I figure is a hack. 
> daemontools is great because it restarts processes automatically when rebooting. But the svc and svstat haven’t proven that useful in my experience. And daemontools is state-of-the-art 2004. I’m looking at
> systemd (which netstyle.ch uses to start and stop its hundreds of client images from requests sent to the box), which I think supersedes the daemontools feature set. And I understand, it will be PID1 default
> on some Linuxes in the near future. It is possible that sometime the use of daemontools on Squeak boxes might be reconsidered. Not my decision, of course, but as the topic came out, I thought I’d brain dump.
> I want to like daemontools more than I find I’m able to. 
> 
> And on the topic of systemd, I’d say this, it’s a big leap. Back up everything and review what you know about GRUB2. I’ve found that out the hard way. I’m learning on a dedicated laptop and I lost my UI.
> Couldn’t get it back. Could only get a terminal on tty1. So I created an install stick and re-installed Ubuntu 14.04 from USB. Now I can try, fail, and have a back up plan, learn more about GRUB2, systemd,
> /etc/default/grub, systemctl, unit config files, etc. I don’t think anybody would want that experience on a production box. It’s a dramatic leap. Oh yea. 
> 
> Chris 
> 
>
>       On Oct 21, 2014, at 7:27 AM, Levente Uzonyi <leves at elte.hu> wrote:
> 
> Hi All,
> 
> I tried to update my Squeak image today, and found that source.squeak.org is down. On box2 I found that it's using all the cpu. Based on the apachelogs it went down 7-8 hours ago.
> I decided to restart it. svc -t didn't kill the image (nor did -k), instead it spawned another image, so I stopped svc, killed the process manually, and restarted it with svc.
> The image is up now, but I wonder if there's anything else to do when a SqueakSource image goes down.
> 
> Levente
> 
> 
> 
>