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Base-Path Handling

Additionally, you can opt-in to automatically handle routing base-paths.
This is useful to make your service available behind a reverse-proxy or similar setup. To do this, you need to use this method:

  • Full Path: UserProfileService.Hosting.ApplicationBuilderExtensions.UseReverseProxyPathBases
  • As extension: appBuilder.UseReverseProxyPathBases(Configuration)

This extension will look for these settings, and configure your application accordingly:

Base-Path example configuration 
{
    "Routing": {
        "PathBase": "",
        "DiscardResponsePathBase": ""
    }
}

When setting Routing:PathBase, your application will accept requests to all of your usual endpoints (/api/foo), but also those that have the configured Prefix (/service/api/foo).
This ensures compatibility with or without reverse-proxy, and pushes consumers of your API to use endpoints with their respective PathBase.
You can check HttpContext.Request.PathBase to see if the current request was handled with or without base-path.
If Routing:PathBase is set, all redirects will be relative to the configured PathBase, even for those that were handled without it.

  • /api/foo redirecting to the api/bar-endpoint will instead be redirected to /service/api/bar
  • /service/api/foo redirecting to the api/bar-endpoint will also redirect to /service/api/bar

When setting Routing:DiscardResponsePathBase your application will behave as if Routing:PathBase was set, but instead of changing all redirects to use the configured prefix, it will be removed from all redirects.

  • /api/foo redirecting to the api/bar-endpoint will still be redirected to /api/bar
  • /service/api/foo redirecting to the api/bar-endpoint will instead redirect to /api/bar

Technical notes to Base-Path handling

There are three components to the Base-Path handling, one of which is hidden. - PathBase - Endpoints will also be bound with this as prefix - ResponsePrefix - Ensures outgoing responses use this prefix in their path - DiscardResponsePathBase - Removes this path from the start of all outgoing responses

For simplicity's sake we chose to omit RequestPrefix and always use it together with PathBase, which leaves only Options 0 (no settings), 2 (PathBase), and 4 (DiscardResponsePathBase).

Using these three settings in different configurations results in these Use-Cases:

Option 0 - Fallback

  • No option used
  • Endpoints bound using Base=/
  • Redirects always use PathBase=/

Without any configuration services will use Option-0, they will only be bound and respond to the endpoints defined in the code.
To use this configuration each service needs its own hostname or ip to respond to.

Option 1 - Not Supported

  • PathBase=/service
  • Endpoints bound using Base=/ and Base=/service
  • Redirects keep the Base they originally arrived with

Basically the same as Option-2, but doesn't show or encourage use of endpoints with a defined Base.

Option 2 - Target-Default

  • PathBase=/service + RequestPrefix=/service
  • Endpoints bound using Base=/ and Base=/service
  • Redirects will always use Base=/service

Basically the same as Options-1, but pushes consumers to use endpoints with a defined Base.
We chose to implicitly use Option-2 and hide Option-1, to hopefully reduce bugs related to path-mapped services.

Option 3 - Not Supported

  • RequestPrefix=/service
  • Endpoints bound using Base=/
  • Redirects will always use Base=/service

While writing this extension we could find no real use-case for Option-3.

Option 4 - Supported just in case

  • DiscardResponsePathBase=/service + (RequestPrefix="" & PathBase="")
  • Using DiscardResponsePathBase with any other option did not lead to usable results
  • Endpoints bound using Base=/ and Base=/service
  • Redirects will always use Base=/

While we don't expect usage of Option-4, we can see scenarios where this configuration makes sense, so we added it to this extension.
Using DiscardResponsePathBase with any other setting did not produce usable results, so we chose to treat its use with other settings as an error.