:: Re: [DNG] docker/virtualization (wa…
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Skribent: Isaac Dunham
Dato:  
Til: Nate Bargmann
CC: dng
Gamle-emner: Re: [DNG] The show goes on: “su” command replacement merged into systemd on Fedora Rawhide
Emne: Re: [DNG] docker/virtualization (was: The show goes on...)
On Sun, Aug 30, 2015 at 09:11:01PM -0500, Nate Bargmann wrote:
> And all along I thought a "dock" had to do with a place to put program
> icons on a desktop and that "docker" was a tool to handle it. I've
> ignored everything about virtual machines except for Virtual Box and
> QEMU.
>
> Evidently, I now have to know that a "container" is a virtual machine.
> Or is it? Seems like more buzz words for buzz words sake.


Not quite, though close.
There are several levels of virtualization:
-chroots (a different /, but same resources)
-containers (different resources, same kernel handling them; built on
"namespaces", so one kernel can have programs with different network,
cpu, filesystem, and other resources)
-hypervisors (different kernel, but relying on shims to use host OS
drivers: Xen and KVM can fall here)
-virtual machines (OS runs on "virtual" hardware, but most instructions
get executed directly on the processor; Virtual Box, Virtual PC, some
Xen/KVM deployments, and Qemu+kqemu fall here)
-emulators (every instruction is emulated; Qemu, various arcade emulators,
and so on fall here)

The difference is that a container is a set of programs on the same
kernel, but with all their resources restricted to a subset of what the
real hardware has.

HTH,
Isaac