In recent times a new kind of computing system has emerged: a distributed infrastructure composed of multiple physical sites in different administrative domains. This model introduces significant new challenges: common configuration parameters must be shared, local customization must be supported, and policy domains must be respected. We believe that such features can best be implemented by a system that provides a high-level configuration language (allowing structuring and validation of configuration information) and that is modular (allowing for flexible structuring of the overall infrastructure). The Quattor configuration management toolkit has been designed to meet these requirements. Quattor uses a declarative model where high-level descriptions are translated into configurations and enacted by autonomous components running on the configured machines. Quattor's Pan language provides features for composing complex configuration schemes in a hierarchical manner, for structurin...