dockerfile-generator

Dockerfile Generator

Produce a production-grade multi-stage Dockerfile for a .NET app: fast cached builds, a small secure runtime image, and a non-root user.

Input — point it at your project

Works on a target: a project/solution or GitHub URL. Detect the entry project and TFM: find <target> -name "*.csproj" and read <TargetFramework>. Note solution layout for correct copy/restore.

Multi-stage Dockerfile

# build
FROM mcr.microsoft.com/dotnet/sdk:9.0 AS build
WORKDIR /src
COPY ["MyApp/MyApp.csproj", "MyApp/"]
RUN dotnet restore "MyApp/MyApp.csproj"          # restore as its own layer = cached unless csproj changes
COPY . .
RUN dotnet publish "MyApp/MyApp.csproj" -c Release -o /app/publish /p:UseAppHost=false

# runtime (small + non-root)
FROM mcr.microsoft.com/dotnet/aspnet:9.0-noble-chiseled AS final
WORKDIR /app
COPY --from=build /app/publish .
USER $APP_UID                                     # non-root (chiseled images set this)
EXPOSE 8080
ENTRYPOINT ["dotnet", "MyApp.dll"]

.dockerignore (don't ship junk / bloat context)

**/bin/
**/obj/
**/.vs/
**/.git/
**/*.user
Dockerfile*

Image-size options (smallest → most compatible)

• -chiseled — minimal, no shell, non-root by default. Best default for services.
• -alpine — small, musl libc (watch native deps).
• -noble/standard — largest, most compatible.
• AOT + runtime-deps for tiny self-contained images when the app is AOT-compatible.

Principles

• Restore before copying source so dependency layers cache (huge build-time win).
• Run as non-root — chiseled images do this for you.
• Smallest base that runs your app — chiseled/distroless reduce attack surface.
• Keep the build context lean with .dockerignore.
• Pin base image tags; don't use latest in production.

How to use it & best prompts

"Dockerize this .NET app", "give me a multi-stage Dockerfile", "shrink my image / use a chiseled image", "non-root container for my service". Pairs with cicd-pipeline-generator and microservice-template-generator.