The traditional approach of having a single point of authentication and authorization worked well in the monolithic architecture. However, in the case of microservices, you would need to do this for each and every service. This would pose a challenge of not only implementing it but keeping it synchronized as well.
The OAuth 2.0 authorization framework and the OpenID Connect 1.0 specifications combined together can solve the problem for us. OAuth 2.0 describes all the roles involved in the authorization process that meets our needs pretty well. We just have to make sure that the right grant type is picked up; otherwise, the security will be compromised. OpenID Connect authentication is built on top of the OAuth 2.0 protocol.
Azure Active Directory (Azure AD) is one of the providers of OAuth 2.0 and OpenID Connect specifications. It is understood here that Azure AD scales very well with applications and integrates well with any organizational Windows Server Active Directory.
As we have already discussed containers, it is important and interesting to understand that containers are very close to the host operating system's kernel. Securing them is another aspect that can't be overrated. Docker was the tool we considered, and it provides the necessary security by means of the least privilege principle.