Recently, the open-source management and orchestration (OSM) platform has attracted significant interest from academia and industry, potentially providing network function virtualization (NFV) management and orchestration solutions for European Telecommunications Standards Institute (ETSI) compliant NFV implementations. OSM has a built-in monitoring module (MON), a policy-management module (POL), and a Prometheus time-series database for metrics collection, which are the main components of ensuring service assurance in OSM. In this work, auto-scaling testing is performed with OSM after instantiating network service using the OSM community-developed virtual network functions (VNFs) and the Grafana tool for data visualization. The Prometheus database collects the metrics from the MON exporter, and scaling actions are defined in POL. Finally, we performed auto-scaling testing and demonstrated the results using the Grafana dashboard. The results showed that the auto-scaling policy was automated successfully after the virtual infrastructure manager (VIM) and VNF metrics triggered threshold violation alarms (already defined) and scaling actions were performed successfully as defined in POL.