Читать книгу The Official (ISC)2 CCSP CBK Reference - Leslie Fife, Aaron Kraus - Страница 68

Virtualization is a core technology in cloud computing. It allows resource pooling, multitenancy, and other important characteristics. Containers are one approach to the virtualization. In a traditional virtualization environment, the hypervisor sits atop the host OS. The VM sits atop the hypervisor. The VM contains the guest OS and all files and applications needed in that VM. A machine can have multiple VMs, each running a different machine.

In containerization, there is no hypervisor and no guest OS. A container runtime sits above the host OS, and then each container uses the container runtime to access needed system resources. The container contains the files and data necessary to run, but no guest OS. The virtualization occurs higher in the stack and is generally smaller and can start up more quickly. It also uses fewer resources by not needing an additional OS in the virtual space. The smaller size of the container image and the low overhead are the primary advantages of containers over traditional virtualization.

Containers make a predictable environment for developers and can be deployed anywhere the container runtime is available. Similar to the Java Virtual Machine, a runtime is available for common operating systems and environments. Containers can be widely deployed. This improves portability by allowing the movement of containers from one CSP to another. Versioning and maintenance of the underlying infrastructure do not impact the containers as long as the container runtime is kept current.

The container itself is treated like a privileged user, which creates security concerns that must be addressed. Techniques and servers exist to address each of these security concerns such as a Cloud Access Security Broker (CASB). Security concerns exist and must be carefully managed. All major CSPs support some form of containerization.