How to Run a C# CLI App with Docker

Docker is a useful container technology for running code / workloads anywhere. You can configure your container with infrastructure as code so that it builds and runs the same thing on any computer with Docker installed.

In this post we'll discuss running a C# CLI app with Docker.

Creating a C# Console App

To create a console app, we can use the dotnet new console command.

(This assumes you have the dotnet sdk installed. If not, you can grab it from the Microsoft website or just copy and paste the code in this post).

This spits out a simple Program.cs:

// See https://aka.ms/new-console-template for more information
Console.WriteLine("Hello, World!");

And an App.csproj:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net9.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

</Project>

Typically you would run this with the dotnet run command and it will output Hello, World!.

Running with Docker

To run with Docker, we'll create a Dockerfile which specifies how to build and run the container.

• Start with a dotnet 9 sdk base image
• Copy the .csproj into the container and run dotnet restore to clean / dl packages
• Publish the app
• Create a new layer with aspnet and run the app

Dockerfile

FROM mcr.microsoft.com/dotnet/sdk:9.0-bookworm-slim AS build
WORKDIR /source

# copy csproj and restore as distinct layers
COPY ./*.csproj ./
RUN dotnet restore

# copy and publish app and libraries
COPY . .
RUN dotnet publish -c release -o /app

# Copy build / styles into final location

FROM mcr.microsoft.com/dotnet/aspnet:9.0
WORKDIR /app
COPY --from=build /app .
ENTRYPOINT ["dotnet", "App.dll"]

To run this, we'll use docker run $(docker build -q .) which builds the image in the current directory with no tags and then immediately runs it.

If you're curious, this looks very similar to how you'd run F# in a Docker container - this makes sense as they both run on dotnet so require similar things.

Next

The full source code is available in this post but if you want access to the project files themselves, you can get it in the HAMY LABS Example Repo on GitHub, available to all HAMINIONs Members.

If you liked this post you might also like:

• Build Tailwind v4 + Daisy UI with Dotnet + Docker
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• How to Run a Simple Python Program in a Docker Container