Set X-Binder-Launch-Host header or binder_launch_host parameter

[manics]

Set the X-Binder-Launch-Host header when pass-through proxying or the binder_launch_host query parameter when redirecting.

See jupyterhub/binderhub#1031 for the corresponding BinderHub PR.

The last step of this is to add

    def badge_base_url(handler):
        launch_host = (
            handler.request.headers.get('X-Binder-Launch-Host', '') or
            handler.get_argument('binder_launch_host', ''))
        if launch_host and not launch_host.endswith('/'):
            launch_host += '/'
        if launch_host == 'https://mybinder.org/':
            return launch_host
        return ''
    c.BinderHub.badge_base_url = badge_base_url

to the Gesis BinderHub configuration

[choldgraf]

should this wait for jupyterhub/binderhub#1031 before merging? it seems reasonable to me though I don't fully understand the implications since I'm not following that PR closely. I see @bitnik is on that thread, maybe they have thoughts here too?

[bitnik]

yes, you are right, this has no effect if jupyterhub/binderhub#1031 is not merged

[manics]

@choldgraf If you're happy with the code here I think the final signoff for this and jupyterhub/binderhub#1031 together should be for @bitnik since it's to help customise the Gesis mybinder links. It should be safe to merge them in either order since neither will have any effect unless there's also a binderhub config change, and that's only needed for Gesis.

[choldgraf]

Sounds good - in that case I am +1 when @bitnik is +1

[bitnik]

I think we can merge this.