I'm developing a command line (in Golang) which interacts with Docker. It works fine on Linux & Mac, although I have a bug when I try to make it work with Windows 10, but I don't have a Windows 10 laptop available.
What are my solutions ? I've tried the nested virtualization, but Hyper-v (which is used by Docker Desktop) is not able to start in my Windows virtual machine (created with VirtualBox which obviously doesn't support thise use case).
The Cloud providers don't seem to support this use case either, I'm kind of stucked.
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My question is: If you use Docker tool box (that is required for windows 10 home to run Docker) you are essentially using a virtual machine (vm)?
If you are using a vm already the only reason to use docker from that point is to save on many more multiple instances?
Meaning if you only want 1 extra (guest instance): you can have a vm. Though, with docker (toolbox on windows 10 home) you would have 1 vm and it runs docker?
The only way that is useful is if you want many more instances as in: 1 vm + 1 docker or + 1000 more dockers?
Or am I missing something?
Yes, docker toolbox uses Oracle VirtualBox cause Windows 7, 8, and Windows 10 home cannot use Hyper V. And yes, If you are using a VM already the only reason to use docker from that point is to save on many more multiple instances but it also allows easy backup and deployment. But you are losing a decent amount of memory when running a VM and then even more when you are running docker.
So although Docker CE will tell you your Windows doesn't support Hyper-V, this isn't always the case (if you check in System Info you might have Hyper-V enabled, if you're on an Insider build or many builds on GPU computers after Anniversary update then you probably have Hyper-V on Windows 10 Home). There are a few workarounds until the Docker team addresses this issue.
You could use Docker from inside WSL (Windows Subsystem for Linux). Microsoft claims WSL accesses everything directly without Hyper-V so this should be theoretically at the same speed. Of course you can't use your GPU at all because of limitations with GPU passthrough on WSL, which you can ask to be resolved here.
You can also use Docker Toolbox as the other answer stated with Virtualbox, but this will be inherently much slower as you're virtualizing a container inside a virtualized container. You should be able to theoretically get GPU support through this, as well as other features e.g. GUI that you wouldn't be able to with WSL.
To answer the "usefulness" portion of the question:
It's also useful if you run code on a server, but need to develop/debug/update it. You want to test it locally, but to make sure the environment in which it executes is the same (to avoid unexpected, environment specific behavior), you use Docker both locally and on the server. In such a case, even though it's slow, I'll spin up a VM on my W10 Home laptop and run Docker in it.
The greatest feature of the Windows 10 Home May 2020 Update is Windows Subsystem for Linus 2. You can docker in it without the need for a complete virtual machine as in Virtual Box.
Install Docker Desktop that it will automatically indentify WSL2.
I'm using dockers on a Windows server 2016, to run all sorts of Windows applications/tasks.
There are several solutions to manage dockers, such as swarm and marathon, but they don't work on Windows (or do work on Windows but via virtual box vm, which is problematic for my needs).
In the future mesos and dc/os will support Windows, but in the meanwhile,
is there an alternative that can work for Windows?
I'd suggest setting up a docker container to manage the rest of your docker.
A couple containers which do exactly that:
http://portainer.io/
DockerUI
If you don't like that you could use a (local) gui to manage it, the only one I know of is:
simple-docker-ui
Docker on Windows appears to be what's coming built into Windows Server 2016? and supports running Windows inside a Docker container and using Windows as a Docker container host. Does this support Linux? I don't think so, I think it only supports running Windows Docker containers. This also appears to be maintained by Microsoft.
Docker for Windows appears to be a separate install created by the Docker team to bring Linux Docker to Windows. So Windows can be the Docker host but all containers are still just normal Linux containers. Does this support Windows containers? I don't think so, I think it only supports running Linux Docker containers. This also appears to be maintained by Docker.
One other interesting note is that Docker Tools for Visual Studio appears to only support Docker Desktop for Windows and not Docker on Windows.
What I'm really looking for are the stated differences bettwen the two, some sort of good comparison. What features are each trying to acheive, where are they similar, where are they different. Will they always be different or will they ever come together?
Docker on Windows is a colloquial way to refer to just the Docker Engine running on Windows. I find it helpful to think of this as a Windows Container Host, so yes Windows containers only. This would be what you would run on a Windows Server 2016 machine. So maybe a better name is Docker for Windows Server which I believe people have used as well. I still prefer a Windows Container Host. Which means it only has the Docker Engine at the end of the day, doesn't even need to have any of the Docker clients (docker CLI, docker-compose, etc).
Docker Desktop for Windows is a product meant for running both Linux and Windows containers on Windows. It's not meant for a production environment, and instead is meant for a desktop/client SKU of Windows, hence the Windows 10 requirement. So you could think of this as Docker for Windows 10. Because DfW can run both container types, there are different configurations that it sets up on your machine:
When using Linux Containers, DfW creates a MobyLinuxVM with Hyper-V inside of which it runs Linux containers, transparently, as if they were running on the Windows 10 host.
When using Windows Containers, DfW installs the same components as Docker on Windows so that you have a Windows Container Host. You have the Windows Docker Engine setup now. This then allows you to run windows containers on a Win 10 client SKU.
Theoretically you could install DfW on Windows Server, I haven't tried so I don't know if this would fail, but why would you want to run Linux containers on a Windows Host in production? In production, you would have Linux Container Hosts that run linux containers and Windows Container Hosts that run windows containers, this would avoid overhead and simplify things.
Just to add on top of Wes's answer on Docker for Windows and few details about the experimental LCOW which is what you are looking for a side by side execution of Windows and Linux containers on the Windows host machine.
Right now there are two ways to run Linux containers with Docker for Windows and Hyper-V:
Run Linux containers in a full Linux VM - this is what Docker
typically does today.
Run Linux containers On Windows (LCOW) with Hyper-V isolation - this is a new option in Docker for Windows.
In the 1st approach, Docker for Windows windows will have docker daemon service on the Windows host machine as well as it will be available on Linux MOBY VM. So basically, you will have 2 different docker hosts. One which is running on your Windows Host Machine, Managing only Windows Containers and other which is running on your Linux Moby VM and Managing only Linux Containers.
It is important to note that, All Linux Containers will share a Single Linux Kernel on Moby VM and All Windows Containers will share Single Windows Kernel on Windows Host Machine.
Things are really getting interesting with the 2nd approach,
Linux containers with Hyper-V isolation run each Linux container in an optimized Linux VM with just enough OS to run containers. Each Linux container has its own kernel and its own VM sandbox. They're also managed by Docker on Windows directly.
The main difference here in this approach is that there is only one docker daemon service is running on Windows Host Machine and managing both Windows and Linux containers.
All Windows Containers will Share Single Windows Kernel while Each Linux Container will have its own Linux Kernel
To understand more in details, please refer
https://learn.microsoft.com/en-us/virtualization/windowscontainers/deploy-containers/linux-containers
I am running a game on Windows, and it requires every OS can only run one. And If I want to run more, currently I open vmware and run the game inside. But the problem is it takes too much memory and disk to run a whole another virtual OS. I know docker will reduce this, but it doesn't seem to support Windows.
Am I right? If so, any other solutions?
Docker uses LXC (linux containers) so cannot run a Windows operating system.
You can use docker on Windows using a boot2docker VM, but this is not the same as docker running a Windows operating system (your containers will run unix based operating systems inside the boot2docker VM).
To do what you're after, you'll need to use separate VMs.
I need a virtual server for web development, it'll host Apache+Postgres+Ruby+something else.
What's the most effective software to run such a server? (ie with least virtualization overhead)
Is there a way to run Linux as as service?
I use VirtualBox at the moment, but it's inconvenient in some ways, such as it needs an emulator window open which also captures keyboard input when alttabbed into.
(Also, coLinux hangs at boot on my machine, so it's probably not an option)
Check out the features of VMWare Server. It's free, you just have to register.
I've never found VMware to be much of a performance hog unless running 3+ virtual machines.
The latest free server version (VMware Server 2) runs as a service IIRC, so you can set up your dev server to start up and shut down when your PC does, and you can either log on to the VM's console through the web interface, or create a shortcut on your desktop so it's fairly non-obtrusive.
There is a very convenient utility that hides VirtualBox from the foreground completely: vboxctrl. With vboxctrl you can run a Linux server on your Windows machine, make it automatically go to sleep when Windows shuts down or hibernates; then use any SSH client to log in to the server. Or you can use Xming to open graphical windows from the Linux server; I've worked quite a lot of time in GVim open through Xming.
If anyone needs more details, leave a comment, I may write an article about this.