In this post we will look at how the STS could be combined with Keycloak to both authenticate users and to retrieve the roles associated with a given user. Typically, Keycloak is used as an IdM for authentication using the SAML SSO or OpenId Connect protocols. However in this post we will leverage the Admin REST API.
I have created a project on github to deploy the CXF STS and Keycloak via docker here.
1) Configuring the STS
Checkout the project from github. The STS is configured is a web application that is contained in the 'src' folder. The WSDL defines a single endpoint with a security policy that requires the user to authenticate via a WS-Security UsernameToken. The STS is configured in spring. Essentially we define a custom 'validator' to validate the UsernameToken, as well as a custom ClaimsHandler to handle retrieving role claims from Keycloak. We also configure the STS to issue SAML tokens.
UsernameTokens are authenticated via the KeycloakUTValidator in the project source. This class is configured with the Keycloak address and realm and authenticates received tokens as follows:
Here we use the Keycloak REST API to search for the user matching the given username, using the given username and password as credentials. What the client API is actually doing behind the scenes here is to obtain an access token from Keycloak using the OAuth 2.0 resource owner password credentials grant, something that can be replicated with a tool like curl as follows:
- curl --data "client_id=admin-cli&grant_type=password&username=admin&password=password" http://localhost:9080/auth/realms/master/protocol/openid-connect/token -v
- curl -H "Authorization: bearer <access token>" http://localhost:9080/auth/admin/realms/master/users -H "Accept: application/json" -v
Role claims are retrieved via the KeycloakRoleClaimsHandler. This uses the admin credentials to search for the (already authenticated) user, and obtains the effective "realm-level" roles to add to the claim.
2) Running the testcase in docker
First build the STS war and create a docker image for the STS as follows:
- mvn clean install
- docker build -t coheigea/cxf-sts-keycloak .
- docker pull jboss/keycloak
- docker-compose up
Now we will use SoapUI to invoke on the STS. Download it and create a new SOAP project using the WSDL of the STS (http://localhost:8080/cxf-sts-keycloak/UT?wsdl). Click on 'Issue' and select the request. We need to edit the SOAP Body of the request to instruct the STS to issue a SAML Token with a Role Claim using the standard WS-Trust parameters:
<t:Claims xmlns:ic="http://schemas.xmlsoap.org/ws/2005/05/identity" xmlns:t="http://docs.oasis-open.org/ws-sx/ws-trust/200512" Dialect="http://schemas.xmlsoap.org/ws/2005/05/identity">
<ic:ClaimType xmlns:ic="http://schemas.xmlsoap.org/ws/2005/05/identity" Uri="http://schemas.xmlsoap.org/ws/2005/05/identity/claims/role"/>
Click in the Properties box in the lower left-hand corner and specify the username and password for the user you created in Keycloak. Finally, right click on the request and select "Add WSS UsernameToken" and hit "OK" and send the request. If the request was successful you should see the SAML Assertion issued by the STS on the right-hand side. In particular, note that the Assertion contains a number of Attributes corresponding to the roles of that particular user.
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