Managing the infrastructure of a large and complex data center can be extremely difficult without taking advantage of recent technological advances in administrative automation. Puppet is a seasoned open-source tool that is designed for enterprise class centralized configuration management. At the RHIC and ATLAS Computing Facility (RACF) at Brookhaven National Laboratory, we use Puppet along with Git, GLPI, and some custom scripts as part of our centralized configuration management system. In this paper, we discuss how we use these tools for centralized configuration management of our servers and services, change management requiring authorized approval of production changes, a complete version controlled history of all changes made, separation of production, testing and development systems using puppet environments, semi-automated server inventory using GLPI, and configuration change monitoring and reporting using the Puppet dashboard. We will also discuss scalability and performance results from using these tools on a 2,000+ node cluster and 400+ infrastructure servers with an administrative staff of approximately 25 full-time employees (FTEs).