Emma, a cloud security engineer at VisionSky Ltd., has the responsibility of isolating applications from the underlying infrastructure and facilitating communication through well-defined channels. To achieve this objective, she utilized an open-source technology that assisted her in creating, packaging, and executing applications. Additionally, the technology offers Platform as a Service (PaaS) through OS-level virtualization, supports containerized software packages, and accelerates the delivery of software. What is the cloud technology implemented by Emma in the described situation?