Multi-tenancy and basic auth

[ciegler]

This mini sample project uses the quarkus-multitenancy extension form
mathias82, which is in the process of becoming an official quarkiverse extension.

All parts that I directly copied (without adjusting) from the quarkus-multitenancy demo project are marked by a comment.

The quarkus-multitenancy extension provides a consistent tenant resolution in quarkus, e.g. via a HTTP-Header.
Hereby the extension lets us implement (if needed) our custom:

• TenantContext
• TenantResolver
• TenantDataSourceRegistry
• TenantResolutionContext
• ...

The extension itself comes with a filter that resolves the tenant if there is no authorization needed and supports a database-per-tenant approach.

In order to resolve the tenant when making an authorization request it is needed to implement a custom
HTTPAuthenticationMechanism and to implement a custom TenantResolutionContext.

Implementing a custom HTTPAuthenticationMechanism is one of the intended ways when customizing Quarkus Security
(see docs).

The extensions build-in TenantResolutionContext expects an ContainerRequestContext, which is not available in the
authentication step. However, to resolve the Tenant via the TenantResolver we only need to extract a specific HTTP-Header,
which we can also get from the RoutingContext.

Testing

Run docker compose up -d to create the databases in the compose.yaml, then run mvn quarkus:dev.
HTTP Requests for testing are in the localhost.http, all passwords are password.

There will be an error message that the database schema for <default> is not correct. I will look into it again, but since it did not affect the project at all I decided to ignore it for now.