I successfully created a profile on my NixOS server.

Rendered docs:

cc @NixOS/php

One thought without looking into too deeply: Couldn't the extension/probe bit be part of the file with all other extensions? It has support for extensions that depends on other extensions.

In my experience, separate files are better for automated updates (that reminds me I still need to write an updateScript) and as fair as I can tell the dependencies to other extensions are done through the PHP attribute, which I am passing to callPackage (would be nicer if the extensions were a separate scope with its callPackage but top-level callPackage seems to work now). Also I do not think blackfire depends on anything, or anything on blackfire.

Though there are some incompatible extensions, maybe we could assert that they are not enabled at the same time?

In my experience, separate files are better for automated updates

Hmm, then we maybe should make a directory for php extension derivations and start splitting out things from "the big file" of all packages and extensions that we have today.