juju isn't really config management.. its orchestration, and its been around since before that was cool (4yrs). thankfully orchestration is in revival mode as the hot thing in devops is containers which obviate a good portion of the install side of config management, and leaving discovery, provisioning, resource management, etc around.

maas is standalone.. and is pretty cool imo, as a an api for controlling baremetal machines (ipmi, libvirt, pxe, etc) with cross os support and used on everything from super computers to intel nucs.