Gitpod: Support opening Gitpod using HTTP Referrer

[trieloff]

For my example project (https://github.com/trieloff/helix-helpx/blob/master/README.md) I've added an "edit in gitpod.io" button to the README.md.

While it is nice to have, the URL right now is hardcoded:

[![Gitpod](https://img.shields.io/badge/edit%20in-gitpod.io-blue.svg)](https://gitpod.io#https://github.com/trieloff/helix-helpx)

It would be great if I could just link to https://gitpod.io/referrer and GitPod would open the referring repository, so that the button could work across forks (and give you an easy way to ensure viral distribution)

[geropl]

That'd be a cool feature. We thought in the same direction but discovered that GitHub does not send URL paths but a plain https://github.com instead.

[trieloff]

Hm. Seems to be browser-dependent. I tried it in Safari (read Referrer using Javascript, not HTTP header) and got the full URL.

[svenefftinge]

Hm. Seems to be browser-dependent. I tried it in Safari (read Referrer using Javascript, not HTTP header) and got the full URL.

Oh, that's cool. Let's re-check for firefox and chrome.

[geropl]

I did a quick test with a README.md on a GitHub repository and console.log(document.referrer) (Chromium and Firefox). Both returned https://github.com/, which is correct as github.com responds with the Referrer-Policy: origin-when-cross-origin, strict-origin-when-cross-origin.

[svenefftinge]

Closing this as we don't seem to get the needed information :(

[svenefftinge]

Good news! It seems like GH have changed the referrer-policy. See #688