New attempt

Dockerfile

@@ -1,21 +1,35 @@
-FROM mcr.microsoft.com/dotnet/aspnet:7.0 AS base
+FROM mcr.microsoft.com/dotnet/runtime-deps:7.0-alpine AS base
 WORKDIR /app
 EXPOSE 5000
 
-FROM mcr.microsoft.com/dotnet/sdk:7.0-bullseye-slim-amd64 AS build
-WORKDIR /src
+FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:7.0-alpine AS build
 ARG TARGETARCH
-ARG TARGETOS
-RUN arch=$TARGETARCH \
-    && if [ "$arch" = "amd64" ]; then arch="x64"; fi \
-    && echo $TARGETOS-$arch > /tmp/rid
+ARG BUILDPLATFORM
+
+WORKDIR /src
 COPY *.csproj .
-RUN dotnet restore -r $(cat /tmp/rid)
+RUN dotnet restore -r
 COPY . .
 WORKDIR "/src"
-RUN dotnet publish -c Release -o /app -r $(cat /tmp/rid) --self-contained false --no-restore
+RUN dotnet build -c Release -o /app/build -a $TARGETARCH
 
-FROM base AS final
+FROM build AS publish
+RUN dotnet public -c Release -o /app/publish \
+    --self-contained true \
+    /p:PublishTrimmed=true \
+    /p:PublishSingleFile=true \
+    -a $TARGETARCH
+
+FROM --platform=$BUILDPLATFORM base AS final
+ARG TARGETARCH
+ARG BUILDPLATFORM
+
+RUN adduser --disabled-password \
+  --home /app \
+  --gecos '' dotnetuser && chown -R dotnetuser /app 
+
+USER dotnetuser
 WORKDIR /app
-COPY --from=build /app .
-ENTRYPOINT ["dotnet", "MauMau-Server.dll"]
+
+COPY --from=publish /app/publish .
+ENTRYPOINT ["./MauMau-Server"]