How to connect to resources like Database, AD etc from Asp Dotnet Core application running in container

Hi All,

I am new to Docker containers. I am still in learning phase. Appreciate your patience.
I have an Asp DotNet core application which I want to containerize it. Application uses LDAP authentication. Once authenticated it pulls data from database and displays on the web page. Application works as expected in when I am running it from local (when connected to office network) or development box (as expected).

Once I start the docker and run the application I can access the Login page but could not authenticate. This I was expecting to fail because office AD is not accessible in container. For now I bypassed the login and tried to test database part but even database was not accessible from container. I would also like to access office network SMTP server for sending email alerts in another application.

How do I make network resources available to container in general?

Here are my Dockerfile and docker-compose.yml file. Appreciate any help.