[Web-SIG] more comments on Paste Deploy

[Phillip J. Eby]

At 10:02 AM 3/5/2007 -0500, Jim Fulton wrote:
>Entry points add *a* mechanism to make those objects a bit more
>discoverable.  Arguably, specifying an application via:
>eggname#entrypointname doesn't provide much advantage over simply
>specifying the dotted path to an object in a module.

Actually, it provides one very important strategic advantage that I don't 
think has been mentioned in this conversation.  A configuration format that 
can specify project/version information can be used as a single-file 
deployment spec for an easy_install wrapper or buildout-like tool.

The advantage of this for virtual hosting providers in particular is 
significant -- if they support the tool, they can support this one-file 
deployment scheme.

Personally, I don't care for the Paste Deploy syntax -- frankly it's almost 
barbaric.  :)  But the concept of being able to specify stacks, routes, and 
configuration in a plain text format that includes package information for 
automated deployment is nonetheless an important one.

A couple years back, I started writing a library to parse a more 
sophisticated, Python-like syntax to do the same sorts of things, but only 
got as far as the parser.

One discussion was here:

http://mail.python.org/pipermail/web-sig/2005-August/001714.html

The basic idea behind the syntax was that assignments are like keyword 
arguments, and non-assignment statements are positional arguments.

I'm not altogether happy with that syntax either, however, as it has a 
little too much "more than one way to do it", which is one reason I never 
finished the implementation.  There is a library that parses it (and does 
other general-purpose Python-like DSL parsing) at:

ViewSVN:   http://svn.eby-sarna.com/SCALE/
Checkout:  svn://svn.eby-sarna.com/svnroot/SCALE/
Docs: 
http://peak.telecommunity.com/DevCenter/scale.dsl#parsing-declarations

Anyway, all that aside, I think it would be fantastic if we could come up 
with some "universal file format" for single-file configuration and 
deployment of applications (including auto-install of all needed eggs), 
that could get stdlib support and ultimately hosting company support.  This 
would actually give us a leg up on even PHP for ease-of-deployment.

In truth, it doesn't matter if the file *contents* are 
standardized.  Standardization could be as simple as defining a #! line like:

#!/usr/bin/pydeploy2.3 SomeFormatEgg==1.1

Where "SomeFormatEgg" offers a "python.deploy" entry point for running the 
file, and the pydeploy tool obtains the necessary egg and provides 
libraries for the parsing tool to auto-locate and install any eggs needed 
by the body.

This could also be a basis for bootstrapping other systems, including 
perhaps buildouts (e.g. "#!/usr/bin/pydeploy2.4 zc.buildout" at the top of 
a buildout .ini)!

So, while a single content format would be nice, we don't even need that in 
order to get a raw deployment system standard.  Perhaps I should build this 
hypothetical pydeploy tool into setuptools 0.7?