To get started with MSI, you will need a principal that can be used (or let Azure create an identity for us by using the system-assigned identity). To access this feature in Azure App Service, you will have to find the Identity blade in the portal:
Figure 5.6 - Identity blade
As you can see, by enabling a system-assigned identity on Azure App Service, it gets an Object ID, which is the identifier or the resource in Azure AD. If you go to the Enterprise applications feature in your Azure AD tenant, you will be able to find the application here:
Figure 5.7 - Enterprise applications blade
Of course, you do not have to assign a system identity to a resource – in all cases, you can leverage an identity you created previously by using a user-assigned identity.
Remember that services with identities can access all the Azure AD secured resources. If you assign it a wide set of permissions, you may face security...