Gateway with OAuth2 Resource Server for custom tenant

[asenjowork]

Hi, I have created a tenant in fusionauth with the issuer "anyissuer", then I configured a spring cloud gateway with spring boot 3.2.1 with:

spring.security.oauth2.resourceserver.jwt.issuer-uri=http://localhost:9011/.well-known/openid-configuration/018d642c-e707-7349-95c7-ead15f625746
spring.security.oauth2.resourceserver.jwt.audiences[0]=018d642c-a7e8-75b1-96af-1ea04c3b0faa

so doing this, when I tried to access some secure url, I am having the error: The Issuer "anyissuer" provided in the configuration did not match the requested issuer "http://localhost:9011/.well-known/openid-configuration/018d6028-e976-7aef-8d35-d65386e6b448"

however in http://localhost:9011/.well-known/openid-configuration/018d6028-e976-7aef-8d35-d65386e6b448 the issuer in the response is "anyissuer".

I have found in the org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerJwkConfiguration class that in this method

@Bean
        @ConditionalOnProperty(
            name = {"spring.security.oauth2.resourceserver.jwt.jwk-set-uri"}
        )
        ReactiveJwtDecoder jwtDecoder(ObjectProvider<JwkSetUriReactiveJwtDecoderBuilderCustomizer> customizers) {
            NimbusReactiveJwtDecoder.JwkSetUriReactiveJwtDecoderBuilder builder = NimbusReactiveJwtDecoder.withJwkSetUri(this.properties.getJwkSetUri()).jwsAlgorithms(this::jwsAlgorithms);
            customizers.orderedStream().forEach((customizer) -> {
                customizer.customize(builder);
            });
            NimbusReactiveJwtDecoder nimbusReactiveJwtDecoder = builder.build();
            String issuerUri = this.properties.getIssuerUri();
            OAuth2TokenValidator<Jwt> defaultValidator = issuerUri != null ? JwtValidators.createDefaultWithIssuer(issuerUri) : JwtValidators.createDefault();
            nimbusReactiveJwtDecoder.setJwtValidator(this.getValidators(defaultValidator));
            return nimbusReactiveJwtDecoder;
        } 

it is creating the issuer validator with the value of spring.security.oauth2.resourceserver.jwt.issuer-uri property instead of the value of issuer in the response of http://localhost:9011/.well-known/openid-configuration/018d642c-e707-7349-95c7-ead15f625746

So to sum up, is there a way to configure oauth2 resource server with spring boot 3.2.1 to get the openid-configuration from the tenant (resolved specifying http://localhost:9011/.well-known/openid-configuration/018d642c-e707-7349-95c7-ead15f625746 in the spring.security.oauth2.resourceserver.jwt.issuer-uri property) and having a jwtDecorder working properly with de issuer?

The only way I have made this "working" is changin my tenant issuer to be http://localhost:9011/.well-known/openid-configuration/018d642c-e707-7349-95c7-ead15f625746

[dan]

Hiya, welcome to the FusionAuth community!

Hmm, per this doc, you can only use the issuer-uri in specific situations.

To use the issuer-uri property, it must also be true that one of idp.example.com/issuer/.well-known/openid-configuration, idp.example.com/.well-known/openid-configuration/issuer, or idp.example.com/.well-known/oauth-authorization-server/issuer is a supported endpoint for the authorization server. This endpoint is referred to as a Provider Configuration endpoint or a Authorization Server Metadata endpoint.

FusionAuth doesn't support those formats for an arbitrary string. However you could use the tenant id as the issuer, since http://localhost:9011/bafb4319-b7ca-ed27-fa2f-bbdba9d8ec06/.well-known/openid-configuration is a valid endpoint. bafb4319-b7ca-ed27-fa2f-bbdba9d8ec06 is the tenant Id.

Hope that helps.

[asenjowork]

Hi @dan , unlucky with that, it only works with the same value in

spring.security.oauth2.resourceserver.jwt.issuer-uri=http://localhost:9011/018d6028-e976-7aef-8d35-d65386e6b448/.well-known/openid-configuration

and issuer field in the tenant configuration:

If I change the issuer in the tenant configuration to acme.com in example, http://localhost:9011/018d6028-e976-7aef-8d35-d65386e6b448/.well-known/openid-configuration returns "issuer" : "acme.com" in the response but oauth2 or spring security keeps comparing the token iss with spring.security.oauth2.resourceserver.jwt.issuer-uri property:

"java.lang.IllegalStateException: The Issuer "acme.com" provided in the configuration did not match the requested issuer "http://localhost:9011/018d6028-e976-7aef-8d35-d65386e6b448/.well-known/openid-configuration"

what make sense related with the code in org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerJwkConfiguration, but from my point of view, the issuer validation should be againt the response not the property

[asenjowork]

Hi @dan , doing like this https://stackoverflow.com/questions/77919421/spring-cloud-gateway-with-fusionauth-custom-tenant works fine

[dan]

@asenjowork Awesome, I'm glad you figured it out!