Security Improvement: Database connections using integrated service users of cloud providers

[ZuitAMB]

• I have searched the issues of this repository and believe that this is not a duplicate.

Description 💡

Currently, TruBudget can use an optional database in a few containers:

• API (used for session managment)
• Notification service (to user user information like mail addresses off-chain)
• Authbuddy (used for mappings)

At the moment, authentication is performed using simple username/password combinations (see here

From a security point of view, an option to use Role Based Access e.g. of an identity or service user assigned to the container would be even more secure. The password could be replaced by dynamic access tokens, and the rights could be managed and reviewed centrally.

Options are available on various clouds, e.g.:

Azure

• Use Identity to get a token to use as password
• reference
  AWS
• On AWS we could also use their IAM management, to get a token as a one time password
• reference
  Google Cloud
• Google Cloud also support IAM authentication
• reference

Similar features are available on smaller clouds.

If added, such a more advanced authentication pattern should be optional, so also the simpler "username/password" option would stay usable. But the possibility to enable the most advanced authentications, e.g. on for TruBudget containers running on AWS, Azure or Google would be great.

As a start, Azure support would be nice.

[SamuelPull]

Azure Postgresql connection #2113