We have a hybrid Active Directory scenario - an on premises Active Directory server synced with an Azure AD tenant.
We are in the process of migrating our on premise Exchange email accounts to 365.
We have a SPA (JavaScript) that displays calendar events retrieved from a dotnet core web API.
The web API only allows access to users in a specific AD group.
The SPA uses the Fetch API to call the web API with credentials.
The web API currently uses EWS to connect to our on premise Exchange server to read calendar events, using its app pool identity.
The above systems have been developed in-house and run on our internal servers.
We want to update the Web API to read calendar events using the MS Graph API, on behalf of the user. We would like to use the simplest available solution.
We have tried to use the AcquireTokenByIntegratedWindowsAuth method but receive the following error: 'Integrated Windows Auth is not supported for managed users'. My limited understanding of why this doesn't work is because we do not have an ADFS on premise.
One of the Microsoft samples shows a SPA acquiring an access token and passing the token in the header as part of the web API call. This would require us to update the SPA and web API code. We're willing to do that if it's the only solution, but I am hoping someone might offer an alternative where we only need to update the web API.
