Docker image for .net 5

Question

Typically I use following images for .net core 3.1 and it works fine.

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1-buster-slim AS base
FROM mcr.microsoft.com/dotnet/core/sdk:3.1-buster AS build

I have for experimental reason started a new .net 5 project and created dockerfile with following

FROM mcr.microsoft.com/dotnet/core/aspnet:5.0-buster-slim AS base 
FROM mcr.microsoft.com/dotnet/core/sdk:5.0-buster AS build

and have following issue:

 => ERROR [internal] load metadata for mcr.microsoft.com/dotnet/core/sdk:5.0-buster                           0.2s
 => ERROR [internal] load metadata for mcr.microsoft.com/dotnet/core/aspnet:5.0-buster-slim                   0.2s
 => CANCELED [build 1/7] FROM mcr.microsoft.com/dotnet/core/sdk:5.0-buster                                    0.0s
 => => resolve mcr.microsoft.com/dotnet/core/sdk:5.0-buster                                                   0.0s
 => [internal] load build context                                                                             0.0s
 => ERROR [base 1/2] FROM mcr.microsoft.com/dotnet/core/aspnet:5.0-buster-slim                                0.0s
 => => resolve mcr.microsoft.com/dotnet/core/aspnet:5.0-buster-slim

Answer 1

As I read here, it is changed to:

FROM mcr.microsoft.com/dotnet/aspnet:5.0-buster-slim AS base
FROM mcr.microsoft.com/dotnet/sdk:5.0-buster-slim AS build

It is also mentioned on the docker hub with more info:

As part of the .NET 5.0 release, all .NET Docker images (including .NET Core 2.1 and 3.1) have transitioned to a new set of Docker repositories described below. Updates will continue to be made to supported tags in the old repository locations for backwards compatibility. Please update any repository references to these new names. For more information see the .NET 5.0 repository rename announcement.

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EDIT: Image descriptions:

Image	Comments
mcr.microsoft.com/dotnet/runtime:5.0	.NET 5 multi-architecture: Supports Linux and Windows Nano Server depending on the Docker host.
mcr.microsoft.com/dotnet/aspnet:5.0	ASP.NET Core 5.0 multi-architecture: Supports Linux and Windows Nano Server depending on the Docker host. The aspnetcore image has a few optimizations for ASP.NET Core.
mcr.microsoft.com/dotnet/aspnet:5.0-buster-slim	.NET 5 runtime-only on Linux Debian distro
mcr.microsoft.com/dotnet/aspnet:5.0-nanoserver-1809	.NET 5 runtime-only on Windows Nano Server (Windows Server version 1809)

Image description reference.

Answer 2

You do not have to write this yourself. A quick way to go about it is to use the dockerfile generator as explained by Julio Casal in this quick tutorial https://www.youtube.com/watch?v=wQSuZFd01tY.

A sample code for MyApp will look like

FROM mcr.microsoft.com/dotnet/aspnet:5.0 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

ENV ASPNETCORE_URLS=http://+:80

FROM mcr.microsoft.com/dotnet/sdk:5.0 AS build
WORKDIR /src
COPY ["MyApp/MyApp.csproj", "MyApp/"]
RUN dotnet restore "MyApp/MyApp.csproj"
COPY . .
WORKDIR "/src/MyApp"
RUN dotnet build "MyApp.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "MyApp.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "MyApp.dll"]