Re: Moving rc.d scripts to base.tgz

[Michael van Elst <mlelstv%serpens.de@localhost>]

On Sun, Apr 17, 2011 at 09:18:29PM +0000, David Holland wrote:
> On Sun, Apr 17, 2011 at 10:48:25AM +0000, Michael van Elst wrote:
>  > jmmv%julipedia.org@localhost (Julio Merino) writes:
>  > 
>  > >The fact that these things are not configurable nicely, other than by
>  > >editing hardcoded values, is a result of these scripts trying to be
>  > >generic but not really being because people is supposed to edit them
>  > >in place.  This is not the result of a nice design.
>  > 
>  > The nice design is to keep such checks easily edible. Instant flexibility
>  > instead of limited choices chosen by the designers.
> 
> No, because then you have to write shell script (or worse, hack
> someone else's) to get the behavior you want. This limits the
> flexibility to people who have sufficient skills to do that (and who
> trust that skill enough to do it in a production context...)

This is not about simple configuration options versus custom scripting.

The possibility to do custom scripting doesn't prevent others from
using the simple configuration options.


> Also, configuration should not in general be Turing-complete, because
> that makes it too hard to reason about and debug. In this business we
> tend to make configuration Turing-complete when we don't know the
> range of sensible configurations yet or if that range is extremely
> large.

So, the possibility of 'Turing-complete' configuration helps you
exactly in these cases. If you forbid this you limit the range
of 'sensible configurations' to what you define as sensible.


> Hence, for example, sendmail.cf. However, as the environment
> matures the unanswered questions tend to get answered, the outlier
> situations requiring weird configs tend to go away, and eventually the
> Turing-completeness becomes a liability. Hence, in the same example,
> Postfix.

Postfix already reinvented part of sendmail.cf because the simple
configuration options were lacking. And I can assure you, while
sendmail configuration language is cryptic and arcane, the equivalent
postfix configuration not covered by the simple configuration options
is worse to understand or debug or simply impossible.


> I should think we can figure out how to make /etc/daily sufficiently
> flexible that no ordinary sysadmin should ever need to edit it.

And 640k is enough for everyone. Right.


Greetings,
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."