pass important env variable for proxy support in pip

[cenit]

as per title

[dg0yt]

So we can fix online builds, but we still can't build offline when it comes to pip an friends.

[BillyONeal]

Can you point to docs for these and/or what the customer expectation for them is? In general we should be trying to route this stuff through x-download although it's understandable we might be unable to do so for pip.

To be clear, my concern would be customers expecting these variables to control other vcpkg downloads unrelated to pip and they not doing so, for instance, if we select the WinHTTP backend.

[cenit]

https://pip.pypa.io/en/stable/topics/https-certificates/

you mean something like this?
the problem is that unless you have the very very recent pip 24.2+ coupled with a recent python interpreter already installed (not the case for vcpkg python tooling), corporate proxies are not supported without these env variables defined. But if you have your variables defined and you expect to make them enable vcpkg python tooling, you are welcomed with an error since vcpkg masks most of the env variables

[BillyONeal]

But if you have your variables defined and you expect to make them enable vcpkg python tooling, you are welcomed with an error since vcpkg masks most of the env variables

Would it make sense for folks in this situation to opt-in to it by using VCPKG_KEEP_ENV_VARS?

[cenit]

is there any rule written anywhere to say what should pass always if defined and what not and the user has to opt-in?
this env variable is not modifying the build but just enabling tools to work in specific environments