Try It Out

First, check the runtime information for the .NET latest image:

docker run --rm reg.mini.dev/dotnet-runtime --list-runtimes

You should expect a similar response for the relevant version:

Microsoft.NETCore.App 10.0.0 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

For our next test, we will use a multi-stage build using the Minimus .NET Runtime and SDK images to create a simple app that prints a greeting and some OS parameters.

To begin, save the following two files to your project directory:

• dotnetapp.csproj is the project file for a sample .NET application. Link to file
• Program.cs is the entry point for the sample .NET application. Link to file

Next, in the same project directory, save the code below to a Dockerfile:

# -------- Build Stage --------
FROM reg.mini.dev/dotnet-sdk:latest AS build

# Switch to root for permissions
USER root
RUN mkdir -p /dotnetapp && chown -R 1000:1000 /dotnetapp

# Switch back to non-root user
USER 1000
WORKDIR /dotnetapp

COPY --link --chown=1000:1000 ./dotnetapp.csproj .
COPY --link --chown=1000:1000 ./Program.cs .

RUN dotnet publish \
        --no-self-contained \
        -c Release \
        -o /dotnetapp/dist

# -------- Runtime Stage --------
FROM reg.mini.dev/dotnet-runtime:latest

WORKDIR /dotnetapp

# Copy published app from build stage
COPY --from=build /dotnetapp/dist .

# Set the entrypoint
CMD ["dotnetapp.dll"]

Your project directory should now look like this:

project-root/
├── Dockerfile
├── dotnetapp.csproj
└── Program.cs

Note that the framework in the .csproj file should match the image version you are using. The default currently uses version 10 and framework net10.0.

Next, build and run your .NET app. Note that the period . specifies the current directory as the build context:

docker build -t minimus-dotnet-app .
docker run minimus-dotnet-app

You should see the .NET greeting with information about its parameters. For example:

         42                                                    
         42              ,d                             ,d     
         42              42                             42     
 ,adPPYb,42  ,adPPYba, MM42MMM 8b,dPPYba,   ,adPPYba, MM42MMM  
a8"    `Y42 a8"     "8a  42    42P'   `"8a a8P_____42   42     
8b       42 8b       d8  42    42       42 8PP!!!!!!!   42     
"8a,   ,d42 "8a,   ,a8"  42,   42       42 "8b,   ,aa   42,    
 `"8bbdP"Y8  `"YbbdP"'   "Y428 42       42  `"Ybbd8"'   "Y428  

OSArchitecture: X64
OSDescription: MinimOS
FrameworkDescription: .NET 10.0

UserName: app
HostName : 0ae513c51d06

ProcessorCount: 2
TotalAvailableMemoryBytes: 4098605056 (3.82 GiB)
cgroup memory constraint: /sys/fs/cgroup/memory/memory.limit_in_bytes
cgroup memory limit: 9223372036854771712 (8589934592.00 GiB)
cgroup memory usage: 35602432 (33.95 MiB)
GC Hard limit %: 0

Technical Considerations

The .Net Runtime image provided by Minimus is a slim, security-hardened alternative to the public image from Docker Hub. The images are largely interchangeable, with a few differences as noted below.

Terms & Info

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Images are provided "as-is" without warranty of any kind. "Hardened" refers to the security configuration applied at the time of build and does not constitute a guarantee of ongoing security or absence of vulnerabilities. The free tier is provided without support, SLA, or guaranteed patching timelines. Security updates may be applied to paid subscriptions before or instead of free tier images. By pulling or using any image you agree to our Terms of Use.