dotnet-docker-dev-in-container.md

Develop .NET Core Applications in a Container

You can use containers to establish a .NET Core development environment with only Docker and optionally a code editor installed on your machine. The environment can be made to match your local machine, production or both. If you support multiple operating systems, then this approach might become a key part of your development process.

A common use case of Docker is to containerize an application. You can define the environment necessary to run the application and even build the application itself within a Dockerfile. This document describes a much more iterative and dynamic use of Docker, defining the environment and running .NET Core SDK commands within containers via the commandline.

See Develop ASP.NET Core Applications in a Container for ASP.NET Core-specific instructions.

Getting the sample

The easiest way to get the sample is by cloning the samples repository with git, using the following instructions:

git clone https://github.com/dotnet/dotnet-docker/

You can also download the repository as a zip.

Requirements

The instructions below use .NET Core 2.1 RC1 images. It is possible to make this scenario work with .NET Core 2.0 but requires many extra steps and a bit of magic. You do not need to switch to .NET Core 2.1 on your local machine to try out these instructions. They will work fine with .NET Core 2.0 projects.

This approach relies on volume mounting (that's the -v argument in the following commands) to mount source into the container (without using a Dockerfile). You may need to Enable shared drives (Windows) or file sharing (macOS) first.

To avoid conflicts between container usage and your local environment, you need to use a different set of obj and bin folders for each environment.

Make this change with the following steps:

1. Delete your existing obj and bin folders manually or use dotnet clean.
2. Add a Directory.Build.props file to your project to use a different set of obj and bin folders for your local and container environments.

Run your application in a container while you Develop

You can rerun your application in a container with every local code change. This scenario works for both console applications and websites. The syntax differs a bit for Windows and Linux containers.

The instructions assume that you are in the root of the repository. You can use the following commands, given your environment:

Windows using Linux containers

docker run --rm -it -v c:\git\dotnet-docker\samples\dotnetapp:/app/ -w /app/dotnetapp microsoft/dotnet:2.1-sdk dotnet watch run

Linux or macOS using Linux containers

docker run --rm -it -v ~/git/dotnet-docker/samples/dotnetapp:/app/ -w /app/dotnetapp microsoft/dotnet:2.1-sdk dotnet watch run

Windows using Windows containers

docker run --rm -it -v c:\git\dotnet-docker\samples\dotnetapp:c:\app\ -w \app\dotnetapp microsoft/dotnet:2.1-sdk dotnet watch run

Test your application in a container while you develop

You can retest your application in a container with every local code change. This works for both console applications and websites. The syntax differs a bit for Windows and Linux containers.

The instructions assume that you are in the root of the repository. You can use the following commands, given your environment:

Windows using Linux containers

docker run --rm -it -v c:\git\dotnet-docker\samples\dotnetapp:/app/ -w /app/tests microsoft/dotnet:2.1-sdk dotnet watch test

Linux or macOS using Linux containers

docker run --rm -it -v ~/git/dotnet-docker/samples/dotnetapp:/app/ -w /app/tests microsoft/dotnet:2.1-sdk dotnet watch test

Windows using Windows containers

docker run --rm -it -v c:\git\dotnet-docker\samples\dotnetapp:c:\app\ -w \app\tests microsoft/dotnet:2.1-sdk dotnet watch test

The commands above log test results to the console. You can additionally log results as a TRX file by appending --logger:trx to the previous test commands, specifically dotnet watch test --logger:trx. TRX logging is also demonstrated in Running .NET Core Unit Tests with Docker.

Build source with the .NET Core SDK, using docker run

You can build your application with the .NET Core SDK Docker image. Built assets will be in the out directory on your local disk.

The instructions assume that you are in the root of the repository. You can use the following commands, given your environment:

Windows using Linux containers

docker run --rm -v c:\git\dotnet-docker\samples\dotnetapp:/app -w /app/dotnetapp microsoft/dotnet:2.0-sdk dotnet publish -c release -o out

Linux or macOS using Linux containers

docker run --rm -v ~/git/dotnet-docker/samples/dotnetapp:/app -w /app/dotnetapp microsoft/dotnet:2.0-sdk dotnet publish -c release -o out

Windows using Windows containers

docker run --rm -v c:\git\dotnet-docker\samples\dotnetapp:c:\app -w c:\app\dotnetapp microsoft/dotnet:2.0-sdk dotnet publish -c release -o out

More Samples

• .NET Core Docker Samples
• .NET Framework Docker Samples