List of mirrors:
 * [mirror1]: http://repo.aptly.info/system-tests/archive.debian.org/debian-archive/debian/ stretch
 * [mirror2]: http://repo.aptly.info/system-tests/archive.debian.org/debian-archive/debian/ stretch [src]
 * [mirror3]: http://repo.aptly.info/system-tests/archive.debian.org/debian-archive/debian/ stretch
 * [mirror4]: http://repo.aptly.info/system-tests/download.opensuse.org/repositories/Apache:/MirrorBrain/Debian_9.0/ ./

To get more information about mirror, run `aptly mirror show <name>`.