✅ Dockerfile goes where exactly if I have multiple class libraries in a sln?

Do we have anyone experienced in docker and has dockerized c# projects because im trying to follow this guide https://learn.microsoft.com/en-us/dotnet/core/docker/build-container?tabs=windows But I got multiple class libraries in my .sln which im probably have to create a seperate container for. and this guide creates only one container for the console application. As of now im confused where I need to place my dockerfile. Should I have one for each directory: API, Services, NectoProtocolGateway and shared?

Containerize an app with Docker tutorial - .NET

In this tutorial, you'll learn how to containerize a .NET application with Docker.