Mitchell Hentges 63bcbe6843 Bug 1755516: Expose config variable for Mach native dependency source r=ahal ...

Adds support and documentation for the
`MACH_BUILD_PYTHON_NATIVE_PACKAGE_SOURCE` environment variable.

The "fallback" behaviour here should be backwards-compatible, which will
enable us to piece-by-piece explicitly use the `"system"` where
needed, then remove the backwards-compatibility shim afterwards.

A restriction added by this change is that it's no longer possible to
have the combination of:
* Have Mach use the system Python, and
* Have the active command site do `pip install`.

This is because this case shouldn't be necessary (if `pip install` is
allowed, why use the system?) and will allow us to enforce that all
non-build command sites always use their lockfiles, when they're set up.

When referring to behaviour in CI, I've opted to only refer to the
upcoming behaviour (of `MACH_BUILD_PYTHON_NATIVE_PACKAGE_SOURCE="none"`)
because the current heuristic behaviour feels complex enough that it
should be understood by checking the code, rather than docs. Besides,
the heuristic will be removed pretty soon (right? ;)

Differential Revision: https://phabricator.services.mozilla.com/D138932

2022-03-10 20:41:54 +00:00

..

index.rst

Bug 1755516: Expose config variable for Mach native dependency source r=ahal

2022-03-10 20:41:54 +00:00