document env vars

[ahdinosaur]

forking from #19, 🍴

here is an issue to document prebuildify's environment variables: 🌟

• ARCH
• PLATFORM (proposed in allow overriding platform for cross-compiling #20)
• PREBUILD_ARCH
• PREBUILD_PLATFORM
• PREBUILD_NODE_GYP
• STRIP (proposed in allow overriding strip command for cross-compilation #19)

i'm also curious about the reason for both ARCH and PREBUILD_ARCH, and whether we should commit to one or the other.

cheers! ❤️

[ralphtheninja]

It seems to me that PREBUILD_ARCH and PREBUILD_PLATFORM aren't used inside prebuildify and not inside node-gyp. I'm guessing they are meant to be passed on to preinstall and postinstall scripts?

[vweevers]

They were introduced in #12. Could you shed some light on this @jimpick?

[ralphtheninja]

They were introduced in #12. Could you shed some light on this @jimpick?

Actually, #12 introduced PREBUILD_PLATFORM and PREBUILD_NODE_GYP but PREBUILD_ARCH seems to have been introduced earlier. Just fyi.

[jimpick]

You can see where I used it here:

https://github.com/jimpick/utp-native-prebuilds-nodejs-mobile/blob/master/build-ios-arm64.sh#L15

I think PREBUILD_NODE_GYP was needed with the particular cross-compiling toolchain I was using (from nodejs-mobile) to get it to use a specific node-gyp path.

It's been a while since I did it, and I didn't keep the prebuilds updated, but you can see where I used PREBUILD_PLATFORM here:

https://github.com/jimpick/sodium-native/blob/ios-prebuild/preinstall.js#L12

I never created a PR for that fork as it was targeting a rapidly evolving toolchain from nodejs-mobile, and I didn't expect the upstream sodium-native developers to have to maintain those prebuilds (or myself, for that matter).

[ralphtheninja]

@ahdinosaur As @jimpick just linked, it seems we want to use PLATFORM in the same way as PREBUILD_PLATFORM above so it makes sense to rename PLATFORM to PREBUILD_PLATFORM in #20