Infrastructure-from-Code (IfC) is a new approach to DevOps and an advancement of Infrastructure-as-Code (IaC). One of its key concepts is to provide a higher level of abstraction facilitated by new programming languages or software development kits, which automatically generate the necessary code and configurations to provision the infrastructure, deploy the application, and manage the cloud services. IfC approaches promise higher developer productivity by reducing DevOps-specific tasks and the expert knowledge required. However, empirical studies on developers’ performance, perceived ease of use, and usability related to IfC are missing. We conducted a controlled experiment (n=40) to assess the usability of the cloud programming languages (PL) and software development kits (SDK). Both approaches involve similar effectivity. We found that the PL-based approach was moderately less efficient but increased correctness with time spent on programming. Tracing generated infrastructure configurations from code was more challenging with the SDK-based approach. Applying thematic analysis, 19 themes emerged related to usability barriers, supporting factors, security, cloud cost, and enhancement areas. We conclude with five findings and future directions.