1. A method comprising: storing, in volatile or non-volatile storage, a set of one or more drift rules; wherein a first drift rule in the set of one or more drift rules identifies a set of one or more attributes and a source; applying, by one or more computing devices, the first drift rule from the set of one or more drift rules to a particular target that is associated with the first drift rule by comparing a first configuration of the set of one or more attributes on the particular target to a second configuration of the one or more attributes on the source; wherein the set of one or more attributes is a subset of a plurality of attributes for which configuration might change from the source, and wherein the plurality of attributes include other attributes that are not in the subset; based on comparing the first configuration of the set of one or more attributes on the particular target to the second configuration of the one or more attributes on the source, determining that the first configuration of the set of one or more attributes on the particular target does not match the second configuration of the one or more attributes on the source; in response to determining that the first configuration of the set of one or more attributes on the particular target does not match the second configuration of the one or more attributes on the source, outputting, by the one or more computing devices, notification data that indicates that the particular target has drifted from the source.