HTTP CORS headers

[tsenart]

In order to enable web-browsers to use the Mesos DNS HTTP API, we have to set appropriate CORS headers. See https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS

Thanks @mhausenblas for reporting.

[jdef]

What's the use case for this? A javascript-backed, mesos-dns driven discovery console/UI?

[mhausenblas]

Indeed @jdef if you want to do service discovery directly from a web app/client-side, like I showed at XebiCon and you can see me struggle at it around minute 6:40 here … workaround in this version of the app was to have a Chrome plug-in that handles CORS. In the current version of the demo app I built a simple proxy that also takes care of CORS.

[tsenart]

I used this successfully in the past: https://github.com/streadway/handy/blob/master/cors/cors.go

Unfortunately, the HTTP library we're currently using violates the sacrosanct http.Handler interface :-(

[rsiebeling]

Hi, is this solved? I need to query mesos-DNS from my frontend to discover the backend server and this isn't possible due to the CORS issue...

[jdef]

I don't think anyone has solved this yet. The HTTP lib that we're using seems to implement support for CORS. If anyone wanted to make an initial contribution to the project, this would be a good fit.

[rsiebeling]

Maybe I could help, but will need some assistance, never did a pull request, I have no experience in Go and do not have that much time. Maybe I'm not the best person to take this up...
However if nobody take this up and someone could help me get started I'd be happy to do this, looking at the comment from tsenart it shouldn't be too hard