Wrong redirect when using self-hosted Kratos

[Arno500]

Hello!

I'm not sure if I am doing something wrong, but it seems there is an assumption here that may not be correct in cases of self-hosted Kratos:
https://github.com/ory/elements/blob/fdabadf8cb2e0ec4fd9286a5277516f8fd69aa0c/packages/nextjs/src/utils/rewrite.ts#L32C1-L32C62

In my Kratos config, I have:

kratos:
  kratos:
    config:
      serve:
        public:
          base_url: https://auth.example.com
          cors:
            allowed_origins:
              - http://localhost:3042
              - https://auth.example.com

      selfservice:
        default_browser_return_url: https://example.com
        allowed_return_urls:
          - http://localhost:3042/*
          - https://example.com/*

        methods:
          webauthn:
            config:
              rp:
                id: example.com
                origin: https://example.com:443/auth/login

        flows:
          error:
            ui_url: https://example.com/error
          
          settings:
            ui_url: https://example.com/settings

          recovery:
            ui_url: https://example.com/auth/recovery
          
          verification:
            ui_url: https://example.com/auth/verification
            after:
              default_browser_return_url: https://example.com
          
          logout:
            after:
              default_browser_return_url: https://example.com
          
          login:
            ui_url: https://example.com/auth/login

          registration:
            ui_url: https://example.com/auth/registration

Every time I start a flow, I get redirected to the UI URLs specified in the config, as-is.
In the linked code above, we can see it tries to match the base URL (let's say https://auth.example.com with the redirect https://example.com/auth/login). Of course, this do not match, it gives up and returns the URL as-is from the backend. It seems a bit weird to me that Ory HAS to be hosted on the same domain as the actual app handling the flows. I suppose this is something specific to the hosted version of Kratos/Ory services, and I also suppose the headers passed are supposed to mitigate this issue, but they do not have any effects in the self-hosted version, it seems.

I'm absolutely open to making a PR if required; I just want to make sure there was no oversight on my side first!

Thanks a lot.

[jonas-jonas]

I am not entirely sure if I fully understand the issue here.

The linked rewrite URLs are for the hosted version of the Ory Account Experience on Ory Network only, and the nextjs middleware is only really made for working with Ory Network projects (mainly to solve cookie issues).

If you're running self-hosted Kratos, you can host both on the same local domains (e.g. kratos.my-app.local or all on different subpaths of localhost). You're going to have to do that anyway, because of the aforementioned cookies issues (Kratos can't set cookies on a domain that's not its own).