1. A method for pairing a server, comprising: receiving, from an unpaired server, a pairing request that includes a pairing key; determining whether to approve or reject the pairing request, comprising attempting to validate the pairing key in the pairing request; and responsive to determining to approve the pairing request: notifying the unpaired server that the unpaired server is now a managed server; generating a description of the managed server, wherein the managed server description includes a set of one or more labels that describe the managed server; generating management instructions for the managed server based on the managed server description and based on an administrative domain-wide management policy that includes a rule that refers to managed servers using a label; and sending the management instructions to the managed server.