A CoreOS Clustering developer designs, develops, and manages clusters of servers using CoreOS, an open-source lightweight operating system. Their tasks include configuring and maintaining CoreOS clusters, deploying containerized applications using technologies like Docker and Kubernetes, ensuring high availability and scalability of systems, and implementing security measures. They also troubleshoot issues, optimize performance, and update or upgrade systems as necessary. They work closely with other developers and IT professionals to ensure smooth and efficient operations. Their work is crucial for businesses that rely on large-scale, distributed systems.