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ASP.NET Core Build Docker Image

This repository contains images that are used to compile/publish ASP.NET Core applications inside the container. This is different to compiling an ASP.NET Core application and then adding the compiled output to an image, which is what you would do when using the microsoft/aspnetcore image. These Dockerfiles use the microsoft/dotnet image as its base.

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What is ASP.NET Core?

ASP.NET Core is a new open-source and cross-platform framework for building modern cloud based internet connected applications, such as web apps, IoT apps and mobile backends. It consists of modular components with minimal overhead, so you retain flexibility while constructing your solutions. You can develop and run your ASP.NET Core apps cross-platform on Windows, Mac and Linux. ASP.NET Core is open source at GitHub.

This image contains:

  • .NET Core SDK so that you can create, build and run your .NET Core applications.
  • A NuGet package cache for the ASP.NET Core libraries. This will significantly improve the initial package restore performance when building ASP.NET Core application.
  • Node.js
  • Bower
  • Gulp

The CI Image (1.0-1.1) contains both the 1.0 and 1.1 pre-restored packages. It is intended for when you have a solution containing both 1.1.x and 1.0.x projects and want to build them all in the same container, gaining advantage of the pre-restored packages. Because it has an extra set of packages it is bigger than the other, more focused, images.

Related images

  1. microsoft/dotnet - the .NET Core image if you don't need the ASP.NET Core specific optimizations.
  2. microsoft/aspnetcore - the ASP.NET Core runtime image, for when you don't need to build inside a container.

Example Usage

Build an app with docker build

With this technique your application is compiled in two stages when you run docker build. The requires Docker 17.05 or newer.

Stage 1 compiles and publishes the application by using the microsoft/aspnetcore-build image. Stage 2 copies the published application
from Stage 1 into the final image leaving behind all of the source code and tooling needed to build.

  1. Create a .dockerignore file in your project folder and exclude files that shouldn't be copied into the container:

     # Sample contents of .dockerignore file
  2. Create a Dockerfile in your project:

     # Sample contents of Dockerfile
     # Stage 1
     FROM microsoft/aspnetcore-build AS builder
     WORKDIR /source
     # caches restore result by copying csproj file separately
     COPY *.csproj .
     RUN dotnet restore
     # copies the rest of your code
     COPY . .
     RUN dotnet publish --output /app/ --configuration Release
     # Stage 2
     FROM microsoft/aspnetcore
     WORKDIR /app
     COPY --from=builder /app .
     ENTRYPOINT ["dotnet", "myapp.dll"]

    This approach has the advantage of caching the results of dotnet restore so that packages are not downloaded unless you change your
    project file.

  3. Build your image:

     $ docker build -t myapp .
  4. (Linux containers) Start a container from your image. This will expose port 5000 so you can browse it locally at http://locahost:5000.

     $ docker run -it -p 5000:80 myapp
  5. (Windows containers) Start a container from your image, get its assigned IP address, and then open your browser to the IP address
    of the container on port 80. To see console output, attach to the running container or use docker logs.

     PS> docker run --detach --name myapp_container myapp
     PS> docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' myapp_container
     PS> docker attach myapp_container

Build an app with docker run

You can use this container to compile your application when it runs. If you use the Visual Studio tooling to setup CI/CD to Azure Container Service then this method of using the build container is used.

Run the build container, mounting your code and output directory, and publish your app:

docker run -it -v $(PWD):/app --workdir /app microsoft/aspnetcore-build bash -c "dotnet restore && dotnet publish -c Release -o ./bin/Release/PublishOutput"

After this has run the application in the current directory will be published to the bin/Release/PublishOutput directory.

Docker Pull Command