Cloud Native (CN) in 5G systems has been identified as a pivotal candidate for operational and capital expenditure savings and, even more, for improvements in system agility and role out of 5G services. This is well reflected on recent 3GPP standardization activities. CN telco is a step forward with respect to Network Function virtualisation (NFV) aiming at embracing a microservice-based architecture. With this in mind, the European Telecommunications Standards Institute (ETSI) has evolved the ETSI NFV reference architecture to adapt to CN and fill the gap with the NFV framework, including containers and Zero-Touch, among other capabilities. Opensource Management & Orchestration (MANO) initiatives, such as Open Source MANO (OSM), are promoting this adoption giving support to CN solutions based on containers. However, at this early stage deployments are currently non-standalone and embedded in VNF-based solutions such as OpenStack. In this context, this paper presents a proof of concept of a full container technology deployment -via Kubernetes- in a NFV architecture. First, a full CN NFV environment is set with the help of OSM MANO, for which we describe the implementation to enable native kubernetes-based Container Network Functions (CNFs) and analyse their performance, limits, advantages and drawbacks. Finally, our solution for CNFs is benchmarked against a typical OSM-OpenStack setup where VNFs are deployed. The results obtained in this work can help to further encourage users and operators to use CNFs and get the most out of containerisation in NFV.