Declarative packaging (Was: Re: Intended MBF: maintainer scripts not using strict mode)

[Niels Thykier <niels@thykier.net>]

Christoph Biedl:
> [...] Niels has mentioned declarative approaches which seem
> like a good idea. No idea about the status, though, and I'm interested
> in details if there already are some.
> 
>     Christoph
> 

Hi,

Up till now, we deal with some easy wins by converting debhelper
maintscripts to triggers.  I plan to phase out the maintscripts from one
more helper in buster (if everything turns out nicely).

 * But then we are out of easy wins.
 * Plus none of this would rid us of manually written scripts (like the
   ones Ralf brought up)

After this, we need something other than triggers.  Triggers are great
for regenerating global caches but they are not good at delegating
targeted functionality out like:

 * This package needs user X to be created dynamically with home set
   to H with login shell S.

 * This package wants to enable and start service Y, but obviously first
   after creating user X (which the service runs as)

 * The user X also needs to own a few files or directories at location
   Z (possibly including the home directory H).  Ideally, this should
   be done before starting the service Y.

Furthermore, we also need to fix some paper-cuts such as #822462, so we
do not regress every time a conffile is removed or changes it name.


The next items in this topic basically all requires changes to dpkg,
which I have not done at this scale yet.  I will probably spend most of
buster on other items (like a few release team processes).

Thanks,
~Niels