Does Docker require Hyper-V enabled in windows? If yes, why?
What is the role of Hyper-V in this case?
I m using Windows 10 home. What is the alternative for hyper-V to install Docker pls?
If you use windows10 professional & your bios supports hardware virtualization, suggest you to enable Hyper-V.
When run linux container in windows10, in fact, it still needs a linux system as a docker host, because linux container cannot share kernel with windows.
If enable hyper-v, docker-windows will auto setup a MobyLinuxVm in hyper-v as a virtual machine which act as the host machine of docker. Compared to traditional solution, I mean install a linux in virtualbox. Hyper-v has much better performance, because it does not depend on windows os, it something like setup based on hardware just like vmware-esx.
Finally, if you use home version of windows10, you had to install a virtualbox as the host machine of docker and use docker toolbox, details refers to https://docs.docker.com/toolbox/overview/ for legacy desktop solution.
Update some additional points you may want to know:
a) linux container:
Docker container had to share kernel with host, there are no linux kernel on windows, so for all situations, you had to have a virtual machine with linux as docker host, either hyper-v or virtualbox if no hyper-v support.
b) windows container:
In theory, windows container could share the kernel of windows, so no virtual machine needed.
But microsoft support container too late compared to linux, so for different host, it use different solutions, see next chapter from microsoft web site:
Windows Containers include two different container types, or runtimes.
Windows Server Containers – provide application isolation through process and namespace isolation technology. A Windows Server Container shares a kernel with the container host and all containers running on the host. These containers do not provide a hostile security boundary and should not be used to isolate untrusted code. Because of the shared kernel space, these containers require the same kernel version and configuration.
Hyper-V Isolation – expands on the isolation provided by Windows Server Containers by running each container in a highly optimized virtual machine. In this configuration, the kernel of the container host is not shared with other containers on the same host. These containers are designed for hostile multitenant hosting with the same security assurances of a virtual machine. Since these containers do not share the kernel with the host or other containers on the host, they can run kernels with different versions and configurations (with in supported versions) - for example all Windows containers on Windows 10 use Hyper-V isolation to utilize the Windows Server kernel version and configuration.
Related
When using Docker for Windows, the containers run side-by-side in a hyper-v linux VM on Windows.
So when launching a container in ubuntu, is any virtualization solution like hyper-v needed or are the containers just running as processes inside ubuntu?
Source for my first statement - How docker desktop runs linux containers on Windows machine
First, why hyper-v?
The reason for docker on windows using hyper-v VM just because: for a linux container, it had to share the linux kernel of host. But on windows, we do not have linux kernel, so docker set a hyper-v VM for you, then let your container to share the kernel.
Second, why not VM on linux?
But on linux, the host already has a linux kernel, so container can share this kernel without using any VM.
In fact, from next diagram you can see when you start a new container, it will auto new a process containerd-shim, it will run as a process which you can use ps aux | grep docker to see it on linux host.
And, finally, what is container?
Docker uses a technology called namespaces to provide the isolated workspace called the container. When you run a container, Docker creates a set of namespaces for that container, then every process in container will run in a separated namespace. See official docementation.
"Containers" is a concept that combines (primarily) two features implemented in the Linux kernel - control groups and namespaces. You need the VM on top of Windows because Windows does not implement these two features.
Therefore, when you run containers natively on Linux, each container will simply run as separate processes constrained by control groups and namespaces.
From what I understand, the container includes all dependencies to run, but all containers running on the same platform whether it's a VM, or bare-metal will share the underlying kernel.
I believe I read somewhere that in order to run linux containers on windows, the Docker client spins up a linux based VM, and runs the container in that.
But now I see that docker for windows runs linux containers natively (ie, without hyper-v).
My question is: How can an image that was built to run on linux run on a system that has a windows kernel?
This is the original source that my question arose from:
https://www.hanselman.com/blog/DockerAndLinuxContainersOnWindowsWithOrWithoutHyperVVirtualMachines.aspx
With the latest version of Windows 10 (or 10 Server) and the beta of
Docker for Windows, there's native Linux Container support on Windows.
That means there's no Virtual Machine or Hyper-V involved (unless you
want), so Linux Containers run on Windows itself using Windows 10's
built in container support.
I saw some similar questions, but they explained how a linux container runs on a windows platform by utilising a vm/hyper-v
How docker desktop runs linux containers on Windows machine
Does "Docker On Windows" launch a linux virtual machine?
Perhaps I didn't understand their answers, but from what I understood, it still seems like the linux container is sitting on-top of the windows kernel.
this is the magic of LCOW (https://github.com/linuxkit/lcow)
you are right to run a container the base KERNEL should be same , since container is just an abstraction , so to run a linux container on windows there are two options
either use moby linux on hyperv and run containers there
use lcow to run light weight linux vm for each container. (lcow)
https://learn.microsoft.com/en-us/virtualization/windowscontainers/deploy-containers/linux-containers
with WSL in windows in future we might be able to get a third method don't know if already someone is working on it .
Docker isn't a VM so it only runs apps native to the OS, right? Does that mean Docker for Windows only runs Windows .exe files? So Docker containers for Windows and Linux, what do they have in common, if anything? Are containers reusable on different operating systems in any way?
"Docker isn't a VM"
Correct, containers should be considered as processes running in a sandbox. If you search about how this isolation takes place in Linux, you'll definitely run into namespaces & cgroups. One definition of containers I've seen lately states that:
"containers are processes born from tarballs, anchored to namespaces and controlled by cgroups"
photo by Dan Mayer, #LeadDevLondon - June 2018
You can also find some interesting stuff regarding linux containers here: Anatomy of a Container: Namespaces, cgroups & Some Filesystem Magic - LinuxCon by Jérôme Petazzoni
Docker for Windows only runs Windows .exe files?
No. Consider that a developer with a Windows PC might work on linux based containers that are later deployed to the cloud. Docker for Windows brings this flexibility, BUT if you run linux containers, these will be running on some kind of virtualization environment. Initially, Docker toolbox was using Oracle Virtualbox, now Docker for Windows uses Hyper-V.
I don't know much about how the isolation takes place inside the Windows OS but I think the logic is similar to Linux. Some info about Windows containers:
Windows Container Types
Windows Containers include two different container types, or runtimes.
Windows Server Containers – provide application isolation through process and namespace isolation technology. A Windows Server Container shares a kernel with the container host and all containers running on the host. These containers do not provide a hostile security boundary and should not be used to isolate untrusted code. Because of the shared kernel space, these containers require the same kernel version and configuration.
Hyper-V Isolation – expands on the isolation provided by Windows Server Containers by running each container in a highly optimized virtual machine. In this configuration, the kernel of the container host is not shared with other containers on the same host. These containers are designed for hostile multitenant hosting with the same security assurances of a virtual machine. Since these containers do not share the kernel with the host or other containers on the host, they can run kernels with different versions and configurations (with in supported versions) - for example all Windows containers on Windows 10 use Hyper-V isolation to utilize the Windows Server kernel version and configuration.
Running a container on Windows with or without Hyper-V Isolation is a runtime decision. You may elect to create the container with Hyper-V isolation initially and later at runtime choose to run it instead as a Windows Server container.
Windows and Linux, what do they have in common, if anything?
In general, I would answer that containers serve the idea of Microservices, separation of concerns, do one thing & do it well.
Are containers reusable on different operating systems in any way?
Yes and No. You may face limitations. For example, if you have an application that starts FROM ubuntu:latest and want to make it work on a raspberry Pi, you will have to build a new container from a base image that is made for arm architecture. Docker is not an abstraction that will take any container and make it work on any architecture, OS... You have to know what you are trying to achieve and carefully make your decisions on what you finally choose to use.
I tried to run Docker on a virtual machine.
Host : MacBook
VM : Parallels Windows 7
And error occurs:
Is it possible?
If the VM is a Linux, you can do this without any problem - on Linux, the Docker is essentially a well-worked chroot. Thus, the Linux docker is not virtualization.
In the case of Windows, it is not so easy. Windows Docker internally uses Hyper-V to emulate the containers. Which means that you can only run, if you can use nested virtualization:
On your host machine runs a Windows VM
Inside your Windows VM, runs a HyperV
HyperV is managed by the docker installed on your virtual Windows.
I tried qemu/kvm, virtualbox and vmware player. I configured them deeply and strongly, I've hacked them, I did every possible to do. Only the last worked (VMWare).
There are significant speed costs, but it may be useful for development on Linux, and then trial-test on Windows configurations.
You will need a lot of ram. At least 16G. 32G is better. A relative useful configuration would be:
32GB physical RAM for the physical host
12GB virtual RAM for the Windows VM running on it
8GB virtual RAM inside the Windows VM for the HyperV Linux host.
Sometimes it will be a little bit buggy, but only your HyperV will crash out, your virtual Win, or your host machine won't. It is okay for testing a docker container on a Windows machine, what you've developed on a Linux. Don't create mission critical servers on this way. :-)
You're using Docker Machine in your Windows VM, which is actually going to create a Linux VM inside the Windows VM on your Mac. You can do that, but you need to enable nested virtualization - which I'm not sure you can do in Parallels 7.
Instead you can run Docker Machine on the Mac directly and use Parallels to create the Linux VM - which means Docker is running in a Linux VM on your Mac, and you don't need nested virtualization.
Or preferably use Docker for Mac if your OS supports it, it's the latest product and has much better host integration than Docker Machine.
If you would be using Windows 10/11 Pro or Enterprise and Hyper-V, then all you must do is to enable nested virtualization. On your host, just run (with your guest off):
> Set-VMProcessor -VMName <VMName> -ExposeVirtualizationExtensions $true
Now you can start your guest and run Docker Desktop as normal.
According to Docker's terms I don't think it's allowed. Section 4.1(b)(vii) says you shall not "use the Service on virtual machines." For clarification, "'Service' refers to the applications, software (including any Open Source Software), products and services provided by Docker, including any beta or trial versions."
If I am reading this right, that means it's illegal to run Docker on any VM.
Worked perfectly fine. Base OS win 10 pro with VirtualBox Version: 6.1 and vagrant with ubuntu 20.04. Using vagrant box follow docker instructions. With vagrant public network no need for port forwarding all apps were accessible.
Previous persons comment is very concerning considering on Windows and Mac you run docker inside a virtual machine lul. Windows uses WSL2 and Mac uses an arm linux machine to manage its docker.
Also, you can run docker in a vm, but it must be linuxOS vm as windows 7 does not support docker.
I have a Linux server with 16GB ram with docker host installed. I would like to deploy on it a Windows Server container. Is it possible? Anyone has just tried this solution?
Update 2019
As noted by duct_tape_coder in the comments:
Microsoft has improved the network options for containers and now allows multiple containers per pod with improved namespace.
In theory (original answer Oct 2015):
There is no "Windows container" running on a Linux host.
And a Linux container would not run directly on a Windows server, since it relies on system calls to a Linux kernel.
You certainly can run those Linux containers on any Windows machine through a VM.
That is what docker toolbox will install.
There will be support for docker on Windows soon, but that would be for Windows container, not Linux containers.
Update 2017: yes, LinuxKit allows to run a linux container through aa Hyper-V isolation wrapper on a Windows platform, through a minimal Linux OS built from linuxkit.
That is still the same idea: linux running inside a VM on Windows.
That is not a Linux server deployed on a Windows server: only deployed inside a Linux server running in a VM on Windows.
Actually... (update Dec. 2016)
See "Linux and Windows, living together, total chaos! (OK, Kubernetes 1.5)"
Kubernetes 1.5 includes alpha support for both Windows Server Containers, a shared kernel model similar to Docker, and Hyper-V Containers, a single-kernel model that provides better isolation for multi-tenant environments (at the cost of greater latency).
The end result is the ability to create a single Kubernetes cluster that includes not just Linux nodes running Linux containers or Windows nodes running Windows containers, but both side by side, for a truly hybrid experience.
For example, a single service can have PODs using Windows Server Containers and other PODs using Linux containers.
But:
Though it appears fully functional, there do appear to be some limitations in this early release, including:
The Kubernetes master must still run on Linux due to dependencies in how it’s written. It’s possible to port to Windows, but for the moment the team feels it’s better to focus their efforts on the client components.
There is no native support for network overlays for containers in windows, so networking is limited to L3. (There are other solutions, but they’re not natively available.)
The Kubernetes Windows SIG is working with Microsoft to solve these problems, however, and they hope to have made progress by Kubernetes 1.6’s release early next year.
Networking between Windows containers is more complicated because each container gets its own network namespace, so it’s recommended that you use single-container pods for now.
Applications running in Windows Server Containers can run in any language supported by Windows. You CAN run .NET applications in Linux containers, but only if they’re written in .NET Core. .NET core is also supported by the Nano Server operating system, which can be deployed on Windows Server Containers.