The text outlines the use of Jenkins Configuration as Code (JCasC), a plugin that allows Jenkins configurations to be managed entirely through code, specifically YAML, rather than through the Jenkins UI. This approach aligns with the infrastructure-as-code methodology, promoting automation, version control, and repeatability. The author provides a detailed walkthrough of setting up a Jenkins controller using JCasC, including global settings, plugins, and agents, all configured in code. The setup process is demonstrated using Docker and Docker Compose, ensuring an easy spin-up and scalability across different deployment environments. The document also touches on agent self-registration and plugin management, highlighting the benefits of avoiding manual UI configuration, which can be tedious and error-prone. Additionally, the text briefly mentions transitioning from Jenkins to Buildkite for scalable CI/CD solutions, showcasing examples from companies like Elastic and Uber that have successfully made the switch.