I am using a mac and apparently installing Docker Desktop is mandatory to use Docker in macOS. Why Docker Desktop is required in Mac and Windows OS, and not in Linux? What purpose Docker Desktop serves? I have tried googling it but can't find appropriate answers.
docker desktop for both mac and windows is using a Linux virtual machine behind the scenes for running regular docker daemon.
Reference
That state docker for windows is using WSL2 which is running a VM.
Here there is a mention of backing up docker VM on docker for mac.
Docker Desktop handles the setup and teardown of lightweight VMs on both Windows and macOS, using Hyper-V on Windows desktops and Hyperkit on macOS.
From docker blog .
Related
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 .
I'm aware that the old Docker Toolbox uses VirtualBox to run a minimal linux virtual machine for Docker using boot2docker which is a minimal light-weight Linux OS. Now, with the new Docker on Windows they claim that they use HyperVisor on Windows 10 Pro directly.
Does this mean the Docker on Windows package got rid of the Linux virtual machine totally, or is there still a Linux virtual machine being used on Windows?
A container is considered “native”, if it can run directly on the host operating system.
Linux Container - A Linux application that runs in an isolated Linux environment.
This same container can be run on a Windows OS using virtualization to emulate a Linux environment, but the container is still running on Linux.
Windows (Server) Container - A Windows application that runs in an isolated Windows environment.
Docker on Windows to run a Linux container requires virtualization. The available options are:
VirtualBox (Docker Toolbox)
Hyper-V backend (Docker Desktop)
WSL2 backend (Docker Desktop)
The Container (and Docker) terminology is very confusing, especially with Windows nuances. See Docker Container in Linux and Windows for an overview with many useful reference links.
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 following scenario:
Windows 7 machine, with an ubuntu virtual machine through virtual box.
I want to know what are the best options for running docker inside the ubuntu?
Can I just install the docker to the ubuntu? Or should I use docker-machine?
The official specs left me confused by saying:
Machine is currently the only way to run Docker on Mac or Windows
So according to that, it would mean I do need the docker-machine, since my base system is Windows?
Why couldn't I just install docker to the virtual machine ubuntu, and use it directly there?
I believe you can but haven't tried this myself. The comment about Docker Machine is related to not being able to run Docker directly on the Windows OS. Docker Machine is spinning up a headless Virtualbox instance of boot2docker with a convenient cli to access it.
Can anyone tell me whether or not it is possible to host Linux-based docker containers on Windows Server 2016 TP5?
I realize that it would have to be through virtualization, but is it possible using the 'standard' Microsoft installation (MSDN Docs) to host linux images? I know it supports Hyper-V isolation, but is that solely for isolation and not for cross platform compatibility?
Given only a single server, what is the best way to be able to host both Windows-based and Linux-based docker containers?
Do I need to install docker twice?
Should I run a Ubuntu server in a VM through Hyper-V?
Should I use the Docker Toolbox (Docker for Windows doesn't support Server 2016 yet)
This is all just for toying around at home, not an actual production environment.
It appears that there is no way of virtualizing Linux Docker containers on Windows other than installing the Docker Toolbox or running it in a VM.
Personally, I installed Hyper-V and an Ubuntu Server VM in that.
Hyper-V containers in Docker for Windows are only for isolation, not cross platform functionality.