Hey there,
after a long time I decided to give the push proxy a try for mobile notifications. To test it I use the push test server provided for this purpose with the app from the Google Play store.
The problem is I don't know how to let mattermost know about the proxy it needs to connect from our network to the external push proxy (http://push-test.mattermost.com).
After I did not find any settings for it and no mentions in neither the docs nor the forums I searched the source code and found some methods that look like they try to extract a proxy from environmental variables. I am however not knowledgable enough to understand the correct context.
I'm currently trying to figure out a way to let the mattermost process know about the environmental variables http_proxy and https_proxy, but since I'm not even sure that is useful I thought I'd ask here and look for some help 
.
BTW this is how the error in the log file looks:[2016/06/16 14:39:29 CEST] [EROR] - github.com/mattermost/platform/api.sendPushNotification:809 - Failed to send push notificationid=[...]8jdbp[...], err=Post http://push-test.mattermost.com/api/v1/send_push: dial tcp 54.152.221.224:80: getsockopt: connection timed out
TL;DR how can I tell mattermost to use a proxy for outbound connections?