Re: thoughts on rudimentary dependency handling

From: Avery Payne <>
Date: Thu, 8 Jan 2015 12:10:34 -0800

On Thu, Jan 8, 2015 at 9:23 AM, Steve Litt <>
> I'm having trouble understanding exactly what you're saying. You mean
> the executable being daemonized fails, by itself, because a service it
> needs isn't there, right? You *don't* mean that the init itself fails,
> right?

Both correct.

> I'm not sure what you're saying. Are you saying that the dependency
> code is in the runscript, but within an IF statement that checks
> for ../env/NEEDS_ENABLED?

Correct. If the switch, which is a data value in a file, is zero, it
simply skips all of the dependency stuff with a giant if-then wrapper. At
least, that's the plan. I won't know until I can get to it.

> > Like I
> > said, this will be a fall-back feature, and it will have minor
> > annoyances or issues.
> Yes. If I'm understanding you correctly, you're only going so far in
> determinint "really up", because otherwise writing a one size fits all
> services thing starts getting way too complicated.

Correct. I'm taking an approach that has "the minimum needed to make
things work correctly."

> I was looking at runit docs yesterday before my Init System
> presentation, and learned that I'm supposed to put my own "Really Up"
> code in a script called ./check.

Also correct, although I'm trying to only do ./check scripts where
absolutely needed, such as the ypbind situation. Otherwise, the check
usually looks at "is the child PID still around".

> If I read the preceding correctly, you're making service tool calls for
> runit, s6, perp and nosh grammatically identical.


> Are you doing that so
> that your run scripts can invoke the init-agnostic commands, so you
> just have one version of your scripts?

Exactly correct. This how I am able to turn the bulk of the definitions
into templates. ./run files in the definition directories are little more
than symlinks back to a script in ../.run, which means...write once, use a
whole lot. :) It's also the reason that features are slow in coming - I
have to be very, very careful about interactions.

> However you end up doing the preceding, I think it's essential to
> thoroughly document it, complete with examples. I think that the
> additional layer of indirection might be skipped by those not fully
> aware of the purpose.

I just haven't gotten around to this part, sorry.

> I can help with the documentation.

Feel free to clone, change, and send a pull request.
Received on Thu Jan 08 2015 - 20:10:34 UTC

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