It is a consensus that the Internet suffers from architectural limitations, including resilience, scalability, and manageability, among others. Therefore, companies access the Internet by establishing a service level agreement (SLA) in the attempt to ensure quality of service (QoS) for users. To address the current limitations of the Internet, researchers have recently proposed the edge as a service (EaaS) paradigm as a suitable solution to improve the access capacity of edge networks. EaaS uses network virtualization and software-defined networks to expand flexibility and manageability of access to edge network resources. Moreover, to maintain QoS assurance for users, EaaS addresses network events (such as traffic overload, failures, etc.) that can potentially affect QoS. Within this context, this paper proposes a software-defined management of EaaS environment, called SDM-EaaS. The proposal enhances the QoS for the end user, while improving the utilization of network resources in dynamic scenarios allowing for unpredictable changes in traffic demands, network infrastructure availability, and customer characteristics. Experiments based on emulation as well as real testbed demonstrate the effectiveness of the SDM-EaaS strategy.