Logout user via Keycloak REST API doesn't work

Question

I have issue while calling Keycloak's logout endpoint from an (mobile) application.

This scenario is supported as stated in its documentation:

/realms/{realm-name}/protocol/openid-connect/logout

The logout endpoint logs out the authenticated user.

The user agent can be redirected to the endpoint, in which case the active user session is logged out. Afterward the user agent is redirected back to the application.

The endpoint can also be invoked directly by the application. To invoke this endpoint directly the refresh token needs to be included as well as the credentials required to authenticate the client.

My request has following format:

POST http://localhost:8080/auth/realms/<my_realm>/protocol/openid-connect/logout
Authorization: Bearer <access_token>
Content-Type: application/x-www-form-urlencoded

refresh_token=<refresh_token>

but this error always occurs:

HTTP/1.1 400 Bad Request
Connection: keep-alive
X-Powered-By: Undertow/1
Server: WildFly/10
Content-Type: application/json
Content-Length: 123
Date: Wed, 11 Oct 2017 12:47:08 GMT

{
  "error": "unauthorized_client",
  "error_description": "UNKNOWN_CLIENT: Client was not identified by any client authenticator"
}

It seems that Keycloak is unable to detect the current client's identity event if I've provided access_token. I've the used same access_token to access other Keycloak's APIs without any problems, like userinfo (/auth/realms//protocol/openid-connect/userinfo).

My request was based on this Keycloak's issue. The author of the issue got it worked but it is not my case.

I'm using Keycloak 3.2.1.Final.

Do you have that same problem? Have you got any idea how to solve it?

Answer 1

Finally, I've found the solution by looking at the Keycloak's source code: https://github.com/keycloak/keycloak/blob/9cbc335b68718443704854b1e758f8335b06c242/services/src/main/java/org/keycloak/protocol/oidc/endpoints/LogoutEndpoint.java#L169. It says:

If the client is a public client, then you must include a "client_id" form parameter.

So what I was missing is the client_id form parameter. My request should have been:

POST http://localhost:8080/auth/realms/<my_realm>/protocol/openid-connect/logout
Authorization: Bearer <access_token>
Content-Type: application/x-www-form-urlencoded

client_id=<my_client_id>&refresh_token=<refresh_token>

The session should be destroyed correctly.