Docker中的共享内核是什么意思？ [英] What is meant by shared kernel in Docker?

问题描述

在Docker中，客户操作系统共享与主机操作系统相同的内核。

有人可以详细说明一下。

让我有一个内核版本的centos os，当我们拉ubuntu的图像，然后它有不同的内核，那么我们怎么说他们有相同的内核？

解决方案

当我们拉ubuntu图像，那么它有不同的内核

不，它没有：它没有内核部分：它依赖于所有

操作系统容器是共享的虚拟环境主机操作系统的内核，但提供用户空间隔离

如上所述在所有Linux发行版都使用相同的内核？中，即使每个发行版都有它自己配置的内核。

In Docker ,guest OS share same kernel as Host OS have .

Can someone elaborate more on it.

Let I have centos os which have some kernel version ,when we pull ubuntu image then it have different kernel ,then how can we say that they have same kernel?

解决方案

when we pull ubuntu image then it have different kernel

No it does not: it does not have the kernel part: it relies on the kernel of the host (the one running docker engine) for all system calls.

As mentioned in "Docker vs Virtualization":

Initially Docker was built as an abstraction layer on top of Linux Containers (LXC). LXC itself is a just an API for the Linux containment features.
Starting with Docker 0.9, LXC is not the default anymore and has been replaced with a custom library (libcontainer) written in Go. Overall libcontainer’s advantage is a more consistent interface to the Kernel across various Linux distributions. The only gotcha is that it requires Linux 3.8 and higher.

See more at "Why Understanding User Space vs. Kernel Space Matters".
Also "Operating System Containers vs. Application Containers":

Containers are the products of operating system virtualization. They provide a lightweight virtual environment that groups and isolates a set of processes and resources such as memory, CPU, disk, etc., from the host and any other containers.
The isolation guarantees that any processes inside the container cannot see any processes or resources outside the container.

OS containers are virtual environments that share the kernel of the host operating system but provide user space isolation

As mentioned in "Do all Linux distros use the same kernel?", a kernel can be shared accross distro, even if each distro has its own configuration of the kernel.

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