How are Dockerfiles used by Visual Studio?

I am trying to create a simple ASP.NET Core web application with React (using the "ASP.NET Core with React.js" template). Further I want to containerize it.

If I run the release configuration, everything works fine. If I run the debug configuration, it seems like the environment variables are not set properly and the npm project is not set up.

As far as I researched, this makes completely sense, as Visual Studio / MSBuild is not execution all stages when building using the debug configuration.

I tried the following steps:

• Adding <ContainerDevelopmentMode>Regular</ContainerDevelopmentMode>
• Adding <DockerfileFastModeStage>final</DockerfileFastModeStage>
• Removing all docker images, volumes and containers

I figured out, that everything I add to the Base-Stage will be applied to the debug container. But that doesn’t make any sense to me.

Which stages are actually included in the image used be Visual Studio / MSBuild? If not all stages are executed, how is the source code passed into the image/container? What entry point is used internally, if only the base stage is built?

My Dockerfile:

#See https://aka.ms/customizecontainer to learn how to customize your debug container and how Visual Studio uses this Dockerfile to build your images for faster debugging.

FROM mcr.microsoft.com/dotnet/aspnet:7.0 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443
RUN apt-get update
RUN apt-get install -y curl
RUN apt-get install -y libpng-dev libjpeg-dev curl libxi6 build-essential libgl1-mesa-glx
RUN curl -sL https://deb.nodesource.com/setup_lts.x | bash -
RUN apt-get install -y nodejs

FROM mcr.microsoft.com/dotnet/sdk:7.0 AS build
WORKDIR /src
RUN apt-get update
RUN apt-get install -y curl
RUN apt-get install -y libpng-dev libjpeg-dev curl libxi6 build-essential libgl1-mesa-glx
RUN curl -sL https://deb.nodesource.com/setup_lts.x | bash -
RUN apt-get install -y nodejs
COPY ["WebsiteLogos/WebsiteLogos.csproj", "WebsiteLogos/"]
RUN dotnet restore "WebsiteLogos/WebsiteLogos.csproj"
COPY . .
WORKDIR "/src/WebsiteLogos"
RUN dotnet build "WebsiteLogos.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "WebsiteLogos.csproj" -c Release -o /app/publish /p:UseAppHost=false

FROM node:16 AS build-web
COPY ./WebsiteLogos/ClientApp/package.json /WebsiteLogos/ClientApp/package.json
COPY ./WebsiteLogos/ClientApp/package-lock.json /WebsiteLogos/ClientApp/package-lock.json
WORKDIR /WebsiteLogos/ClientApp
RUN npm ci
COPY ./WebsiteLogos/ClientApp/ /WebsiteLogos/ClientApp
RUN npm run build

FROM base AS final
WORKDIR /app
ENV ASPNETCORE_HOSTINGSTARTUPASSEMBLIES=Microsoft.AspNetCore.SpaProxy
COPY --from=publish /app/publish .
COPY --from=build-web /WebsiteLogos/ClientApp/build ./ClientApp/build
ENTRYPOINT ["dotnet", "WebsiteLogos.dll"]