Respect NO_PROXY when downloading the binary

[xzyfer]

Turns our handling proxies is complicated. The sanest thing to do
is try matching npm's behaviour, and liable to change to
our benefit. The TLDR; of which is to let request do whatever
it wants unless npm has been explicitly configured otherwise.

Fixes #1724

/cc @nschonni @mmrath

[xzyfer]

@mmrath can you please try applying this diff locally and running npm rebuild node-sass to see if it resolves the issue?

[nschonni]

Maybe i'm reading this wrong https://www.npmjs.com/package/request#controlling-proxy-behaviour-using-environment-variables but I think we can just delete all our proxy code and just let request do it's own thing.

[mmrath]

Awesome! I will test this today. Any chance you can publish a experimental build? If not would you know how to use a local version with this fix?

[mmrath]

@xzyfer, @nschonni I tested this. This PR works fine for me. Any chance you can publish this?

[xzyfer]

@nschonni yes and no

The intent is to match the npm proxy resolution as closely
as possible. As long as a proxy has not been explicitly
configure for npm via npm config set or .npmrc, npm
will simply fallback to letting request determine the
proxy settings.

If a proxy has been explicitly configured for npm
we must respect it above all else.

If the user has not configured a proxy via npm config then must
use that proxy. Request is no aware of the ENV proxy variables
set via npm config.

The mikeal/request package already handles proxy support, including
environment variables http_proxy, https_proxy, no_proxy, and
variants. npm should let request take care of proxying based on
environment variables and only set proxy values if .npmrc has a proxy
specified. By passing a proxy to request, request will always use that
proxy setting and will not honor no_proxy settings. This will enable
the use of a private npm repository that is within a corporate firewall.

npm/npm@40afd6aaf34

[mmrath]

@xzyfer, @nschonni Any chance this can be merged?

[xzyfer]

Blocking myself on this. There should be a test around the npm proxy behaviour as outlined

npm should let request take care of proxying based on
environment variables and only set proxy values if .npmrc has a proxy
specified.

[xzyfer]

I'm comfortable in the test coverage for this now. Waiting on the outcome of #1733.

[mmrath]

@xzyfer Any chance this can be released soon?