We have a solution that uses Certificate-based Authentication with Azure Service Principals on Windows. It's documented in the following article:' Building Daemon or Service Apps with Office 365 Mail, Calendar, and Contacts APIs (OAuth2 client credential flow)
We need a solution similar to the one above that will work on Linux Servers.
The below WIKI by the Azure Identity SDK team has the conceptual documentation here: https://github.com/AzureAD/azure-activedirectory-library-for-dotnet/wiki/Client-credential-flows
The dotnet core sample: https://github.com/Azure-Samples/active-directory-dotnetcore-daemon-certificate-credential
works on Linux however the part of the sample generating the cert will not work as powershell on Linux is based on .net core which doesn't yet support the cert modules required.
