Varnish minus VCL?

[Luke Macpherson]

I am looking to deploy varnish in a configuration which has a large
number of backends, and integrate it with our existing management
infrastructure. I'd like to solicit your opinions on the best way to
do that.

What I'm thinking of doing is using replacing the compiled VCL
configuration object with a custom-written object. This C library
could talk to our existing infrastructure to keep track of live
backends and choose the appropriate one at run-time based on
availability, load and other factors.

Is this a reasonable approach? Is the VCL api stable and well-defined
enough? Is there a better place to plug-in this kind of functionality?

-- 
Luke