Allow downloading gradle binary

[koppor]

Summary

gradle is a a Java build tool. It offers a wrapper, which downloads the build tool by itself. This is possible on Travis, but not on build.snapcraft.io:

Downloading https://services.gradle.org/distributions/gradle-4.0.2-bin.zip

Exception in thread "main" java.io.IOException: Unable to tunnel through proxy. Proxy returns "HTTP/1.1 407 Proxy Authentication Required"

Source: https://build.snapcraft.io/user/JabRef/jabref/67152

Process

1. Create a snap requiring gradlew to build. Example: https://github.com/snapcore/snapcraft/tree/master/demos/gradle
2. Let it build on build.snapcraft.io

Current and expected result

Expected: Download https://services.gradle.org/distributions/gradle-4.0.2-bin.zip succeeds

Current result: Download does not succeed. Download rejected with 407.

Screenshot

[sparkiegeek]

I've proposed canonical/snapcraft#1490 which should fix this by having the gradle plugin pass on the username and password from $http_proxy and $https_proxy down to the build process

[solazio]

Not relevant for snapcraft.io, closing