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

David T. Lewis lewis at mail.msen.com
Tue Oct 21 21:34:01 UTC 2014


On Tue, Oct 21, 2014 at 08:36:55AM -0700, Tobias Pape wrote:
> 
> On 21.10.2014, at 08:30, Chris Cunnington <brasspen at gmail.com> 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. 
> > 
> 
> this is a hack indeed.
> 
> 
> > 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. 
> 
> Perhaps I can help out here and there?
> I use daemontools for some years now without any noticeable problems, really.
> Yes, the mindset is different from other process supervision systems, but 
> then again, each of them has its downsides. I haven't heard too much good
> stuff about systemd; it allegedly does ?too much? (including being a DHCP 
> client and gui interaction?).
>   I'd really like to help to keep daemontools as it is.
> 

+1000

Ken forced me to learn daemontools in order to set up squeaksource.com
on box3, and I am glad that he did. It is the perfect tool for running
Squeak based services on a system like this. Once I figured out how it
worked, it has been no problem at all, and it eliminated the usual hackish
scripts that I might otherwise have been tempted to invent. It is also a
good way to ensure that our various services are managed in similar ways,
so that people other than the original author can figure out how they are
set up, and what to do when they stop working.

FWIW, I don't think I have had to touch anything related to squeaksource.com
since at least last February, and even that was just an image update that
I did through VNC.

Dave



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