Ontologies have become the de-facto information representation method in the semantic web domain, but recently gained popularity in other domains such as cloud computing. In this context, ontologies enable service discovery, effective comparison and selection of IaaS, PaaS and SaaS offerings and ease the application deployment process by tackling what is known as the vendor lock-in problem. In this paper we propose a novel ontology named HOCC: holistic ontology for effective cluster comparison. The ontology design process is based on four different information categories, namely Performance, SLA, cost and environmental impact. In addition we present our approach for populating, managing and taking advantage of the proposed ontology as developed in a real world Kubernetes cluster setting, as well as instantiating the ontology with example services and data (namely performance aspects of a serverless function).