Direct Access Grants (Resource Owner Password Flow) with Spring Boot and Keycloak

gistfile1.txt

This gist describes the process of setting up direct grant access  (oauth2 resource owner password flow) with keycloak and spring boot. We'll follow the
below steps -

1. Install keycloak - there are plenty of examples out there (even a  docker image)
2. Create a demo realm and create a client within the demo realm with the settings as - 
    client-protocol: openid-connect, access-type: confidential, (implicit-flow+direct-access-grant+service-accounts)=enabled
3. Create 2 roles - developer and admin within the demo realm
4. Create 2 users - one with developer role and other with admin (Ensure that user is enabled, there are no "Required User Actions" and that the password has been reset (in the credentials tab)


Now, create a simple Spring Boot application with keycloak Spring Boot adapter. My pom.xml looks like -

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.keycloak</groupId>
      <artifactId>keycloak-spring-boot-starter</artifactId>
      <version>4.3.0.Final</version>
    </dependency>
  </dependencies>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.RELEASE</version>
      </dependency>
      <dependency>
        <groupId>org.keycloak.bom</groupId>
        <artifactId>keycloak-adapter-bom</artifactId>
        <version>4.3.0.Final</version>
      </dependency>
    </dependencies>
  </dependencyManagement>

Create a single resource that we will protect with keycloak like this -

@RestController
public class HelloResource {

  @RequestMapping(value = "/demo/message", method = RequestMethod.GET)
  public String hello(){
    return "Hello World";
  }

}
  
  
Now, the most important bit - the configuration file, in this case application.yml in src/main/resources

###
server:
 port: 8181
logging.level.org.keycloak: trace
logging.level.org.springframework.security: trace

keycloak:
  enable-basic-auth: false
  realm: infinx
  auth-server-url: http://localhost:8080/auth # keycloak server base url
  ssl-required: none
  resource: spring-demo-app ## This is the name of your client in keycloak
  use-resource-role-mappings: false
  bearer-only: true
  credentials:
   secret: xxxxxxxxx-xxx-xxx-xxxx-xxxxx # secret of the client from keycloak UI
  securityConstraints:
  - authRoles:
        - developer  # The role from keycloak
    securityCollections:
        - name: developer stuff
          patterns:
            - /demo/* # only allow developers to access 
  public-client: false
####  

Thats it!, Now run your application.

Testing -
1. Generate a token by invoking keycloak openid endpoint (You can use curl for this purpose)
POST http://localhost:8080/auth/realms/infinx/protocol/openid-connect/token
Accept: */*
Cache-Control: no-cache
Content-Type: application/x-www-form-urlencoded

client_id=spring-demo-app&client_secret=xxxxxxxxx-xxx-xxx-xxxx-xxxxx&username=developer1&password=password&grant_type=password

This should return a bunch of stuff, but most important of all is the access_token

"access_token": "ey......9RgnFhPQ2RbLw"

GET http://localhost:8181/demo/message
Accept: */*
Cache-Control: no-cache
Authorization: Bearer ey......9RgnFhPQ2RbLw

You should be able to access the resource. Now, repeat the steps with admin user and access should be denied.




  
	

Lines 58 through 80 go into your application.yml

Following config (of securityConstraints) is required to protect resources despite policy-enforcer is enabled/disabled.

keycloak.securityConstraints[0].authRoles[0] =*
#You can also list down roles
keycloak.securityConstraints[0].securityCollections[0].name = protected
keycloak.securityConstraints[0].securityCollections[0].patterns[0] = /*
#This configuration enables the policy enforcer in order to protect resources served by this application.
#During the boot, the policy enforcer is going to fetch all protected resources in Keycloak and automatically configure your application.
#Note that protected resources in Keycloak are defined with a URI which maps to a set of resources in this application.
keycloak.policy-enforcer-config.on-deny-redirect-to=/demo_app/accessDenied