.net 核心 Web 应用程序 docker 映像如何在 Mac OS 上运行？

Question

Ok I know I'm being a noob here but I'm trying to get my head around Docker... I've created a simple .net core Web API app that returns some data. I did this in Windows, pushed to gitlab, but then I can clone on Mac and runs fine as expected...

I then create a Dockerfile that includes..

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build-env
WORKDIR /app

...

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1
WORKDIR /app

As I understand it, does the core sdk include the small nano server windows OS? Does that mean that when I use docker run on Mac it's actually running the app on Windows - kind of like in a mini VM on the Mac?

If this is correct, how does docker know to use the windows nano server, rather than a linux image for example?

Thanks for any help

Answer 1

Short Answer:

Because .NET Core is cross-platform. And docker works on Mac and Windows (theoretically just the way it works on Linux) the image will work just fine on any platform.

mcr.microsoft.com/dotnet/core/sdk:3.1 is platform dependent. Depending on the architecture you choose to run Docker it'll pick up Windows Nano server or Linux template.

Long Answer:

Docker is not a VM technology. It's a Linux feature that provides you an isolated environment. Docker is not possible on Windows and Mac. Docker uses Linux features and plugs in an application (and it's related dependencies) in the Linux environment and creates an illusion of resources (network, RAM, disk, software frameworks) needed for running the application.

On windows and Mac. Docker installs a Linux VM. And runs the Docker infra inside the VM.

commands like docker info will give more details. This picture below shows that it's running on Linux.

Switching to Windows docker will give a different output for docker info command.