If you need to modernize a legacy multitenant Puppet codebase that seems too big or risky to change, this talk is for you. We’ll walk through a structured approach to safely modernize old Puppet infrastructure, using automation to manage the risks. In particular, we’ll examine using Onceover (a tool for testing control repositories without writing any tests) to help identify where new changes will break code elsewhere in the baseline—even when you don’t know who owns it, or what it does. We’ll also talk about life after modernization, and how to prevent similar problems in the future. Speaker: Chris Tessmer, Senior DevOps Engineer, Onyx Point, Inc.