Steve Litt <slitt@???> writes:
> On Sun, 30 Aug 2015 21:11:01 -0500
> Nate Bargmann <n0nb@???> 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.
>>
>> - Nate
>
> There's a distinction. A VM is an instance of an entire operating
> system, including kernel. It can run pretty much any OS as a guest.
>
> A container guest uses the host's OS, so the host must be Linux. The
> advantage is very, very quick startup and very low resources, not
> having to run an entire kernel in each instance.
>
> "Docker" is one implementation of a container.

Not really. Linux provides so-called 'control groups' for manageing
process groups and 'kernel namespaces' in order to facilitate presenting
different 'views' of some (set of) kernel subsystem(s) to different
processes. 'Docker' is (collectively) some middleware plus a user
interface for enabling use of these kernel features to run applications
(or groups of applications) isolated from other (groups of)
applications(s) on the same system. As does the original 'Linux
Containers' project,

https://linuxcontainers.org/

and systemd as well.

With their usual, charming, veraciousness, some
systemd advocates like to represent using these features as "systemd
innovations" and the systemd implementation is - also as usual - geared
towards "thou shalt have no others before me".