The engineers describe how they implemented infrastructure as code at Coolblue to automate everything, enable developers, and put everything in code. Key aspects included defining infrastructure through source code, version controlling configurations in GitHub, implementing automated testing, security checks, and code reviews on pull requests, and controlled deployments from testing to acceptance to production environments. This allowed them to achieve transparency, reusability, auditability and quality control while enabling developers and managing Coolblue entirely in code.