In 2021 era of containers, cloud providers still use hypervisor to make it possible to use more of a system’s available resources and provide greater IT mobility since the guest VMs are independent of the host hardware.
Hypervisor, allows a physical server to operate multiple VMs as guests running alongside each other.
Containers are a form of operating system virtualisation.
Both system can achieve same purpose, but containers are much more efficient.
You can say containers are not offer enough security, but zero trust container could be possible.
I still wonder why cloud providers still use hypervisor instead of containerization in their bare metal servers.
Containers are not “a form of operating system virtualisation”. Containers are the way to build multiple user environments in a single OS image. Containers and VMs were never able to achieve the same purpose. Containers are based on technology that was never intended to replace virtual machines at all; it is the way to build jails more secure than, say, chroot (it is like “chroot on steroids”).
If you want to see “a form of operating system virtualisation”, learn about Xen paravirtual technology; that is the form of OS virtualisation.
There are many tasks which is not possible to do in containers, for example, people often need to run both Windows and Linux apps and god only knows what else, and the only way to do that is virtualisation.
Yet there are many tasks that could be solved either way. Why they still aren’t always solved using containers?
Because of inertia in people’s minds. VMs are just like computers, which we use for very long time and everybody is accustomised to them. Containers are very different things.
Because of Windows widespread, which doesn’t have such a concept. I can even speculate that’s because it is hard to enforce licensing restrictions in truly secure containerized environment; Micro$oft licensing terms were always very muddy, but inclusion of containers could make that unbearable even to their most loyal proponents.