To set up Ory Oathkeeper as a proxy to handle CORS (Cross-Origin Resource Sharing) for your backend, you can configure it in the

oathkeeper.yml

file. This approach allows you to manage CORS at the proxy level, eliminating the need to configure CORS for each individual upstream backend. Here's how you can do it: 1. In your

oathkeeper.yml

file, add the following configuration under the

serve.proxy

section:

yaml serve:   proxy:     cors:       enabled: true       allowed_origins:         - <http://127.0.0.1:8080>       allowed_methods:         - POST         - GET         - PUT         - PATCH         - DELETE       allowed_headers:         - Authorization         - Content-Type       exposed_headers:         - Content-Type       allow_credentials: true       debug: true

This configuration enables CORS for the proxy and sets up the allowed origins, methods, headers, and other CORS-related options. You should adjust these settings according to your specific requirements. [Oathkeeper Configuration](https://www.ory.sh/docs/oathkeeper/guides/proxy-websockets#configure-ory-oathkeeper-and-ory-kratos) By setting up CORS at the Oathkeeper proxy level, you can centralize your CORS configuration, making it easier to manage and eliminating the need to configure CORS for each individual upstream backend service. Remember to restart Ory Oathkeeper after making changes to the configuration file for the new settings to take effect.

Based on your description, it seems you're experiencing issues with cross-domain authentication in your Ory setup. Let's troubleshoot this step by step: 1. Cookie Sharing: It's good that your cookie is being shared among subdomains. This is crucial for the setup to work. Make sure the cookie domain is set to the root domain (e.g.,

.<http://example.com|example.com>

) to allow sharing across all subdomains. 2. Oathkeeper Configuration: Ensure that Oathkeeper is correctly configured to use the Cookie Session Authenticator. Your configuration should look similar to this:

yaml
   authenticators:
     cookie_session:
       enabled: true
       config:
         check_session_url: <http://auth.example.com/sessions/whoami>
         preserve_path: true
         extra_from: "@this"
         subject_from: "identity.id"
         only:
           - ory_kratos_session

[Oathkeeper Cookie Session Authenticator](https://www.ory.sh/docs/kratos/guides/zero-trust-iap-proxy-identity-access-proxy#ory-oathkeeper-identity-and-access-proxy) 3. CORS Configuration: Although CORS is working, double-check that it's properly configured in Oathkeeper to allow requests from your CMS subdomain:

yaml
   serve:
     proxy:
       cors:
         enabled: true
         allowed_origins:
           - <http://cms.example.com>
         allowed_methods:
           - GET
           - POST
           - PUT
           - PATCH
           - DELETE
         allowed_headers:
           - Authorization
           - Content-Type
         exposed_headers:
           - Content-Type
         allow_credentials: true

4. Nginx Configuration: Ensure that your Nginx configuration is correctly proxying requests to Oathkeeper and preserving necessary headers, especially cookies. 5. Domain and Subdomain Setup: The setup you described (CMS, Auth, and API on different subdomains) can be tricky. As per the Ory documentation: "Make sure that your application (for example the Quickstart self service app ) and Ory Kratos Public API are available on the same domain - preferably without subdomains. Hosting both systems and routing paths with a Reverse Proxy such as Nginx or Envoy or AWS API Gateway is the best solution." [Ory CSRF Troubleshooting](https://www.ory.sh/docs/kratos/debug/csrf#common-issues) 6. Check Browser Dev Tools: Use your browser's developer tools to inspect the requests. Look at the Network tab to see if the cookie is being sent with requests to

<http://api.example.com|api.example.com>

and

<http://auth.example.com|auth.example.com>

. 7. Verify Kratos Configuration: Ensure that Kratos is configured to accept requests from Oathkeeper. Check the

trusted_proxies

setting in your Kratos configuration. 8. Check Oathkeeper Logs: Enable debug logging in Oathkeeper to get more information about why the authentication is failing.

Based on your description, it seems you're experiencing issues with cross-domain authentication in your Ory setup. Let's troubleshoot this step by step: 1. Cookie Sharing: It's good that your cookie is being shared among subdomains. This is crucial for the setup to work. Make sure the cookie domain is set to the root domain (e.g.,

.<http://example.com|example.com>

) to allow sharing across all subdomains. 2. Oathkeeper Configuration: Ensure that Oathkeeper is correctly configured to use the Cookie Session Authenticator. Your configuration should look similar to this:

yaml    authenticators:      cookie_session:        enabled: true        config:          check_session_url: <http://auth.example.com/sessions/whoami>          preserve_path: true          extra_from: "@this"          subject_from: "identity.id"          only:            - ory_kratos_session

[Oathkeeper Cookie Session Authenticator](https://www.ory.sh/docs/kratos/guides/zero-trust-iap-proxy-identity-access-proxy#ory-oathkeeper-identity-and-access-proxy) 3. CORS Configuration: Although CORS is working, double-check that it's properly configured in Oathkeeper to allow requests from your CMS subdomain:

yaml    serve:      proxy:        cors:          enabled: true          allowed_origins:            - <http://cms.example.com>          allowed_methods:            - GET            - POST            - PUT            - PATCH            - DELETE          allowed_headers:            - Authorization            - Content-Type          exposed_headers:            - Content-Type          allow_credentials: true

4. Nginx Configuration: Ensure that your Nginx configuration is correctly proxying requests to Oathkeeper and preserving necessary headers, especially cookies. 5. Domain and Subdomain Setup: The setup you described (CMS, Auth, and API on different subdomains) can be tricky. As per the Ory documentation: "Make sure that your application (for example the Quickstart self service app ) and Ory Kratos Public API are available on the same domain - preferably without subdomains. Hosting both systems and routing paths with a Reverse Proxy such as Nginx or Envoy or AWS API Gateway is the best solution." [Ory CSRF Troubleshooting](https://www.ory.sh/docs/kratos/debug/csrf#common-issues) 6. Check Browser Dev Tools: Use your browser's developer tools to inspect the requests. Look at the Network tab to see if the cookie is being sent with requests to

<http://api.example.com|api.example.com>

and

<http://auth.example.com|auth.example.com>

. 7. Verify Kratos Configuration: Ensure that Kratos is configured to accept requests from Oathkeeper. Check the

trusted_proxies

setting in your Kratos configuration. 8. Check Oathkeeper Logs: Enable debug logging in Oathkeeper to get more information about why the authentication is failing. If the issue persists after checking these points, you might want to consider simplifying your setup by hosting Kratos and your API on the same domain, as recommended in the Ory documentation. This approach can help avoid cross-domain issues with cookies and authentication. [Ory Migration Guide](https://www.ory.sh/docs/migrate-to-ory#integrate-frontend) Remember, running services on different subdomains can be complex and may require additional configuration to work correctly with Ory's security model.