A Policyfile file allows you to specify in a single document the cookbook revisions and recipes that Chef Infra Client will apply. A Policyfile file is uploaded to the Chef Infra Server, where it is associated with a group of nodes. When these nodes are configured during a Chef Infra Client run, Chef Infra Client will make decisions based on your Policyfile settings and will build a run-list based on that information. A Policyfile file may be versioned, and then promoted through deployment stages to safely and reliably deploy new configuration.