For this tutorial, you download an ASP.NET Core sample app and run it in Docker containers. The sample works with both Linux and Windows containers.
The sample Dockerfile uses the [Docker multi-stage build feature](https://docs.docker.com/engine/userguide/eng-image/multistage-build/) to build and run in different containers. The build and run containers are created from images that are provided in Docker Hub by Microsoft:
The sample uses this image for building the app. The image contains the .NET SDK, which includes the Command Line Tools (CLI). The image is optimized for local development, debugging, and unit testing. The tools installed for development and compilation make the image relatively large.
The sample uses this image for building the app. The image contains the .NET Core SDK, which includes the Command Line Tools (CLI). The image is optimized for local development, debugging, and unit testing. The tools installed for development and compilation make the image relatively large.
The sample uses this image for running the app. The image contains the ASP.NET Core runtime and libraries and is optimized for running apps in production. Designed for speed of deployment and app startup, the image is relatively small, so network performance from Docker Registry to Docker host is optimized. Only the binaries and content needed to run an app are copied to the container. The contents are ready to run, enabling the fastest time from `docker run` to app startup. Dynamic code compilation isn't needed in the Docker model.
The sample uses this image for running the app. The image contains the ASP.NET Core runtime and libraries and is optimized for running apps in production. Designed for speed of deployment and app startup, the image is relatively small, so network performance from Docker Registry to Docker host is optimized. Only the binaries and content needed to run an app are copied to the container. The contents are ready to run, enabling the fastest time from `docker run` to app startup. Dynamic code compilation isn't needed in the Docker model.
In some scenarios, you might want to deploy an app to a container by copying its assets that are needed at run time. This section shows how to deploy manually.
Here's the *Dockerfile* used by the `docker build` command you ran earlier. It uses `dotnet publish` the same way you did in this section to build and deploy.
In the preceding *Dockerfile*, the `*.csproj` files are copied and restored as distinct *layers*. When the `docker build` command builds an image, it uses a built-in cache. If the `*.csproj` files haven't changed since the `docker build` command last ran, the `dotnet restore` command doesn't need to run again. Instead, the built-in cache for the corresponding `dotnet restore` layer is reused. For more information, see [Best practices for writing Dockerfiles](https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#leverage-build-cache).
FROM mcr.microsoft.com/dotnet/core/aspnet:3.0 AS runtime
WORKDIR /app
COPY published/aspnetapp.dll ./
ENTRYPOINT ["dotnet", "aspnetapp.dll"]
```
### The Dockerfile
Here's the *Dockerfile* used by the `docker build` command you ran earlier. It uses `dotnet publish` the same way you did in this section to build and deploy.
```dockerfile
FROM mcr.microsoft.com/dotnet/core/sdk:3.0 AS build
WORKDIR /app
# copy csproj and restore as distinct layers
COPY *.sln .
COPY aspnetapp/*.csproj ./aspnetapp/
RUN dotnet restore
# copy everything else and build app
COPY aspnetapp/. ./aspnetapp/
WORKDIR /app/aspnetapp
RUN dotnet publish -c Release -o out
FROM mcr.microsoft.com/dotnet/core/aspnet:3.0 AS runtime
As noted in the preceding Dockerfile, the `*.csproj` files are copied and restored as distinct *layers*. When the `docker build` command builds an image, it uses a built-in cache. If the `*.csproj` files haven't changed since the `docker build` command last ran, the `dotnet restore` command doesn't need to run again. Instead, the built-in cache for the corresponding `dotnet restore` layer is reused. For more information, see [Best practices for writing Dockerfiles](https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#leverage-build-cache).
FROM mcr.microsoft.com/dotnet/core/aspnet:2.2 AS runtime
WORKDIR /app
COPY published/aspnetapp.dll ./
ENTRYPOINT ["dotnet", "aspnetapp.dll"]
```
### The Dockerfile
Here's the *Dockerfile* used by the `docker build` command you ran earlier. It uses `dotnet publish` the same way you did in this section to build and deploy.
```dockerfile
FROM mcr.microsoft.com/dotnet/core/sdk:2.2 AS build
WORKDIR /app
# copy csproj and restore as distinct layers
COPY *.sln .
COPY aspnetapp/*.csproj ./aspnetapp/
RUN dotnet restore
# copy everything else and build app
COPY aspnetapp/. ./aspnetapp/
WORKDIR /app/aspnetapp
RUN dotnet publish -c Release -o out
FROM mcr.microsoft.com/dotnet/core/aspnet:2.2 AS runtime
The Git repository that contains the sample app also includes documentation. For an overview of the resources available in the repository, see [the README file](https://github.com/dotnet/dotnet-docker/blob/main/samples/aspnetapp/README.md). In particular, learn how to implement HTTPS:
> [Developing ASP.NET Core Applications with Docker over HTTPS](https://github.com/dotnet/dotnet-docker/blob/main/samples/run-aspnetcore-https-development.md)
