Keycloak authentication flow in a microservices based environment - spring-boot

I want to use Keycloak in a microservices based environment, where authentication is based on OpenID endpoints REST calls ("/token", no redirection to keycloak login page), a flow that I thought of would be something like this:
1. Front-end SPA retrieves the tokens from the "/token" endpoint and stores in browser's localStorage, then sends it with every request.
2. Gateway-level authentication: Acess Token is passed from the front end to the gateway, gateway consults Keycloak server to check if the token is still valid (not invalidated by a logout end-point call).
3. Micro-service based authorization: Acess Token is passed from the Gateway to the microservices, using Spring Boot adapter the microservices check the signature of the token offline (bearer-only client?) then based on the role in the token do the authorization.
My questions are: Does this flow make sense or can you suggest another flow? What type of Keycloak clients to use? What's an ideal way to pass Tokens using Spring Boot Adapter, and should it be done like that in the first place? Please keep in mind that I am not a Keycloak expert, I've done my research but I still have doubts.

Your Front-end SPA should be public-client and springboot micro service should be Bearer only Client and Gateway could be Confidential Client.
You can check the Keycloak provided oidc adapters. For springboot you use the keycloak provided adapter
Similar solution using api gateway is discussed here

Related

Spring Cloud - Micoservice Authentication propagation

I am building an application using microservice architecture. I am using Eureka for service discovery with Spring Cloud Gateway for request routing. For authentication mechanism I am issuing JWT tokens (in auth service). What is the best practice when it comes to propagating Authentication so I can get logged user information in each service which is after the gateway?
So far I've came up/found couple of possible solutions:
In gateway add headers for relevant user information, and in each service create filter which would take said headers and create Authentication object and store it into SecurityContextHolder. The downside of this approach is I can't just plug and play services outside my application.
Pass the token coming from the client through the gateway to the each service, where I would have JWTFilter which would validate token and extract the user information. Downside I see with this approach is I have to have jwt secret shared between each service or stored on each service, and I would have to implement JWT logic, producing duplicate code.
Final solution is having something like oAuth token introspection endpoint in auth service which would be called from each service (filter) once the request reaches it.
I implemented the filter logic for validating the user token in the gateway service, but I would like to use role based authorization on each endpoint (service) differently (ie. user service has endpoint for creating users (ADMIN), and for fetching user information (ANY ROLE)).
I opted for something like your option 2 and use spring-boot to configure JWT decoder from an OIDC authorization-server (Keycloak).
Configuring OpenID resource-servers is super easy (more options in parent folder), and authorization-server JWT public signing key is retrieved automatically by spring JWT decoder.
All that is required is ensuring that Authorization header with JWT bearer is correctly propagated between services.

Spring/spring boot authorisation using JWT tokens

Looking for suggestions on how to go about with microservices authorisation.
I'm using the spring/spring boot for all them microservices
I'm able to authenticate via spring cloud gateway before reaching the actual microservices using JWT tokens however when it comes to authorisation i'm unsure on how to do it.
I would like handle the authorisation internally for each of the endpoints in the business microservice.
Is there a way to pass the JWT token to the microservice or do i need to call the authserver to get the roles within the user ?
Actually, both works.
You can put the roles in the token, when you need it, decode it. Or decode it in the gateway and pass it all the way.
If you don't want to put too much data in the token, you can call the auth server as needed.

Microservices architecture - Spring boot - Gateway

I'm developing a back-end with microservices architecture. I'm new about that architecture and for now I have developed 3 microservices (RESTful web services, with Spring Boot) each in a container.
I want to implement OAuth2 and JWT Rest Protection and a gateway.
Is it correct to implement a gateway with Authorization Server and Resource Server?
Am I doing something wrong about the architecture?
Thanks for the replies
As per the standard, should not mix gateway with authorization because both the purposes are different.
Gateway
Gateway can be differentiated in two ways - Internal and External. Purpose of gateway is to route the call from external or internal to the protected resource.
Authorization Server
Authorization server comes into the picture for identity access management. All the request coming from external or internal via gateway should be authenticated or authorized before routing call to the protected resource with JWT or access token etc.
https://medium.com/swlh/authentication-and-authorization-in-microservices-how-to-implement-it-5d01ed683d6f
Authentication and Authorization - There should be a separate service that authentication the user (like supporting OAuth0 type of protocol and providing JWT Token). Your frontend should call API Gateway.
Now question comes at what granular level you are maintaining permissions - Only small set of roles or granular level of permission set. Now API Gateway should communicate with Authorization server with JWT and get the set of roles and permission. Based on the same, API gateway should forward or block the call to Microservice.
Even if you have small set of roles and JWT can be extracted and validated by Gateway but avoid to keep the same at Gateway as there are chances that you have to extract the functionality to some other service in near future.

custom oidc in keycloak

I have a spring based application which does authentication and authorization(oauth2 based) for a client app.I want to now use keycloak to manage my authorizations, but i want to keep my spring code. Basically i want to use my existing auth code as an external identity provider in keycloak.
I am thinking of adding changes in client app such that it receives token from my existing oauth code(which does the authentication) and then exchange this token with keycloak(for session and authorization management). How can i do this? What configurations need to be done in keycloak?
I read about token exchange in keycloak here, but i am not clear about the kind of token i need to send from my existing auth code.
https://www.keycloak.org/docs/latest/securing_apps/
Here is how OAuth2 roles are usually spread:
Keycloak is authorization-server
Spring service is resource-server
front-end is client
user is resource-owner
I have a doubt of you wanting your Spring service to be "authorization-server" as well (serve user identity). If so, I think you should not.
Keycloak (or any other OpenID provider) should be the only authorization-server. Both Spring and client(s) should be configured to use it as so.
To write it differently, Keycloak is responsible for users login and emitting tokens with user ID (subject) and rights (roles or whatever). Other tiers in the architecture (clients & resource servers) get user info from the token and apply relevant security checks (spring security annotations, Angular guards, etc.).
I published a mono-repo for a meetup with minimal sample involving a Spring resource-server and Angular (with Ionic) client talking to a Keycloak OpenID authorization-server. You might find some inspiration browsing it.

How to secure Spring Cloud microservices using Spring Security?

Here is the authorization service. It has endpoints to login and receive a JWT using either a custom username/password or social OAuth (Facebook, GitHub etc.).
I have a Eureka server setup and Zuul gateway service. From what I understand, there are two ways to go about implementing secure microservices. You either proxy requests through the auth service, or you send requests to the requested service (Ex. Service A) and service A authorizes using the auth service.
I would like to use the second way, however I'm having trouble implementing it. Is my understanding correct? Is there a way to setup service A somehow so that certain paths (configured using Ant matchers) will have to authorize using the auth service, which will set the SecurityContext appropriately and inject a UserPrincipal into the request. If anyone can point me to a good guide for this that would be much appreciated.

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