[Grok-dev] a grok installer download Was: Re: remove the download tarball functionality from grokproject?

[Leonardo Rochael Almeida]

On Mon, Mar 1, 2010 at 20:09, Martijn Faassen <faassen at startifact.com> wrote:
> [...]
> Another approach would be to use virtualenv *more*. Instead of installing a
> shared eggs cache, we download all of grok's requirements into the
> site-packages of the virtualenv that our installer creates. This will then
> be our shared eggs cache. It does away with the need of a centralized shared
> eggs cache installed and the need for a centralize default default.cfg for
> buildout. One consequence would be that any *extensions* that the user
> downloads into their buildout would not be shared but in the local 'eggs' of
> each buildout. Is that good or bad?
>
> Another consequence would be that we'd need a way to guarantee that the
> right versions are installed into site-packages, as we can't use buildout to
> do it (or could we hack it to?). Pip?

Another consideration is that going this route would perhaps make us
more compatible with the non-buildout python world, which might,
arguably, make things like using mod_wsgi easier.
> [...]
> Some more requirements:
>
> [...]
>
> * the buildout.cfg created by grokproject should work on other machines. It
> shouldn't have hardcoded paths in it to, say, eggs directories.
>
> [...]
>
> Given these consequences, I am still inclined to stick with the shared egg
> cache approach, even though it does force us to install a default.cfg
> centrally. I think end-users end up with a nicer setup as a result.
>
> It'd be nice if we could somehow avoid this, but I can't see a present or
> future buildout feature right now that would help there (besides a long
> commandline option to bin/buildout, or an alternative bin/rebuild script
> that uses this commandline option. Neither are attractive).

How about a compromise?

Have buildout.cfg extend a "paths.cfg" that concentrate all local
(non-portable) paths. Emptying this file would turn it into a regular
buildout, depending on default.cfg for caching. On the other hand, a
change on a single line in this file would allow alternating between
different grok-installer versions.

It could look something like this:

[buildout]
# adjust this if you download a new version of the grok installer or if you
grok-installer = /home/leo/Downloads/grok-installer-1.2
# change these only if you know what you're doing
eggs-directory =  ${:grok-installer}/eggs
extends-cache = ${:grok-installer}/versions

Or perhaps, simply

[buildout]
# adjust this if you download a new version of the grok installer or if you
grok-installer = /home/leo/Downloads/grok-installer-1.2
extends += ${:grok-installer}/install.cfg

This last version would allow us to change the names and location of
the included version files (ztk.cfg, zopeapp.cfg, ...) with each
released installer.

Cheers, Leo