Azure is the public cloud infrastructure provided by Microsoft and some Partners worldwide. Debian images and support infrastructure inside Azure is maintained by Debian developers at credativ.
There exists high available and distributed Debian mirrors inside Azure. They provide anything for architectures amd64, i386 and source from main and security archive and a temporary local repository.
deb http://debian-archive.trafficmanager.net/debian jessie main deb http://debian-archive.trafficmanager.net/debian-azure jessie main deb http://debian-archive.trafficmanager.net/debian-security jessie/updates main