Spring Cloud Gateway Matching Routes with Path Variables and Custom Filter

Question

I am trying to use the Sprign-Cloud-Gateway to implement role-based-authentication for an application with multiple microservices. I have 3 roles in the application: Customer, Deliverer and Dispatcher and I have a service called customer-authentication-service for creating & managing the JWTs and roles.

This is what I need to do, but could not do:

1. Create a Map of paths that maps the request method and url pattern to the list of roles that can access this url, such as:

    private final Map<Request, ImmutableList<String>> PERMISSIONED_ENDPOINTS = new HashMap<>(){{
        put(new Request(HttpMethod.PUT, "/*/collected/deliverer/*"), ImmutableList.of("DISPATCHER"));
        put(new Request(HttpMethod.PUT, "/*/deposited/deliverer/*/box/*"), ImmutableList.of("DISPATCHER"));
        put(new Request(HttpMethod.PUT, "/user/*/delivered/box/*"), ImmutableList.of("DISPATCHER"));

        put(new Request(HttpMethod.GET, "/customer/{customerId}/status/delivered"), ImmutableList.of("DISPATCHER", "CUSTOMER")); // Only the customer with that id
        put(new Request(HttpMethod.GET, "/customer/{customerId}/status/active"), ImmutableList.of("DISPATCHER", "CUSTOMER")); // Only the customer with that id
    
        put(new Request(HttpMethod.POST, "/boxes"), ImmutableList.of("DISPATCHER", "CUSTOMER));
        put(new Request(HttpMethod.PUT, "/boxes/{boxId}"), ImmutableList.of("DISPATCHER"));
        put(new Request(HttpMethod.DELETE, "/boxes/{boxId}"), ImmutableList.of("DISPATCHER"));
}};

2. Match an incoming request that contains path variables with one of these patterns. I need to match complex paths such as: /{deliveryId}/deposited/deliverer/{delivererId}/box/{boxId}

I couldn't understand how to match these.

3. Send a request to the customer-authentication-service to post the JWT and get the role so that I can check if it is allowed to see the url.

My question:

How should I implement the URL matching and applying custom logic (sending requests to get the role and checking it) with the complex urls that contain path variables. Should I store Pattern objects and compare the incoming request with these, using regexes?

I also checked Predicates and gone through all the docs but couldn't figure out how to implement it exactly. Please provide me with a minimal working example for one of the complex urls and I will figure out the rest.

Something like antMatchers in Spring Security would do the job but I am not sure if adding Spring Security is what I need in this case.

Thanks in advance.

Answer 1

Sorry, I did not understand your question fully. I'll try to answer on the basic of whatever I understand.

What I think is you are looking of HTTP Request Interceptor, which will intercept your every request and then you can check if that URL matches to your desired URL.

Here is link to docs of HandlerInterceptor Interface. You can implement HandlerInterceptor and use preHandle() method where you will get access to incoming request.