I have been looking for example that illustrate how to implement springboot, keycloak and thymeleaf. Where I could use my own login screen and have both a rest controller and view in my application. The reason is that the application is not very complex, but maybe it should be split. In the example I tried to both learn and document the correct approach, but might be way of.

Please use with pessimism.

THIS IS A WORK IN PROGRESS

The request url will first be matched againts a security configuration in org.wyk.application.spring.KeycloakWebSecurityConfiguration.configure if permission is allowed, either by being authenticated already or that the request match an anonomous or un authenticated pattern it will be allowed through.

Next it will be check by if it matches any of the MVC path or resource handlers patterns. org.wyk.application.spring.WebMvcConfiguration

The UsernamePasswordAuthenticationToken is created by the UsernamePasswordAuthenticationFilter, this is configured in the KeycloakWebSecurityConfiguration. The UsernamePasswordAuthenticationFilter filters on POST '/login'. This action is initiated by the login.html form. The filter calls the AuthenticationManager. We have registered our own KeycloakUsernamePasswordAuthenticationProvider with the AuthenticationManager to handle (username + credential) authentication.

The steps in the Authentication process is as follows:

1 ExceptionHandlingFilter

Own Exception Handling. Catch IO and Servlet Exceptions

2 WebAsyncManagerIntegrationFilter

Provides integration between the SecurityContext and Spring Web's WebAsyncManager

3 SecurityContextPersistenceFilter

Populates the SecurityContextHolder with information obtained from the configured SecurityContextRepository prior to the request and stores it back in the repository once the request has completed and clearing the context holder. By default it uses an HttpSessionSecurityContextRepository. See this class for information HttpSession related configuration options. This filter will only execute once per request, to resolve servlet container (specifically Weblogic) incompatibilities. This filter MUST be executed BEFORE any authentication processing mechanisms. Authentication processing mechanisms (e.g. BASIC, CAS processing filters etc) expect the SecurityContextHolder to contain a valid SecurityContext by the time they execute.

4 HeaderWriterFilter

Filter implementation to add headers to the current response. Can be useful to add certain headers which enable browser protection. Like X-Frame-Options, X-XSS-Protection and X-Content-Type-Options.

5 CsrfFilter

Applies CSRF protection using a synchronizer token pattern. Developers are required to ensure that CsrfFilter is invoked for any request that allows state to change. Typically this just means that they should ensure their web application follows proper REST semantics (i.e. do not change state with the HTTP methods GET, HEAD, TRACE, OPTIONS). Typically the CsrfTokenRepository implementation chooses to store the CsrfToken in HttpSession with HttpSessionCsrfTokenRepository wrapped by a LazyCsrfTokenRepository. This is preferred to storing the token in a cookie which can be modified by a client application.

6 LogoutFilter

Logs a principal out. Polls a series of LogoutHandlers. The handlers should be specified in the order they are required. Generally you will want to call logout handlers TokenBasedRememberMeServices and SecurityContextLogoutHandler (in that order). After logout, a redirect will be performed to the URL determined by either the configured LogoutSuccessHandler or the logoutSuccessUrl, depending on which constructor was used.

7 UsernamePasswordAuthenticationFilter

Processes an authentication form submission. Called AuthenticationProcessingFilter prior to Spring Security 3.0. Login forms must present two parameters to this filter: a username and password. The default parameter names to use are contained in the static fields SPRING_SECURITY_FORM_USERNAME_KEY and SPRING_SECURITY_FORM_PASSWORD_KEY. The parameter names can also be changed by setting the usernameParameter and passwordParameter properties. This filter by default responds to the URL /login.

Here we pass in our own provider @see KeycloakUsernamePasswordAuthenticationProvider

8 KeycloakAuthenticationProcessingFilter

Match uri POST '/sso/login' by default, changed it to POST '/login'

or

Request must contain the 'Authorization' Header (Bearer)

or

OAuth2 'access_token'

or

a Cookie matching KEYCLOAK_ADAPTER_STATE

A RequestAuthenticator is create and used to authenticate the request.

9 RequestCacheAwareFilter

Responsible for reconstituting the saved request if one is cached and it matches the current request. It will call getMatchingRequest on the configured RequestCache. If the method returns a value (a wrapper of the saved request), it will pass this to the filter chain's doFilter method. If null is returned by the cache, the original request is used and the filter has no effect.

10 SecurityContextHolderAwareRequestFilter

A Filter which populates the ServletRequest with a request wrapper which implements the servlet API security methods. In pre servlet 3 environment the wrapper class used is SecurityContextHolderAwareRequestWrapper. See its javadoc for the methods that are implemented. In a servlet 3 environment SecurityContextHolderAwareRequestWrapper is extended to provide the following additional methods:

 HttpServletRequest.authenticate(HttpServletResponse) - Allows the user to determine if they are authenticated and 
 if not send the user to the login page. See setAuthenticationEntryPoint(AuthenticationEntryPoint).
 HttpServletRequest.login(String, String) - Allows the user to authenticate using the AuthenticationManager. 
 See setAuthenticationManager(AuthenticationManager).
 HttpServletRequest.logout() - Allows the user to logout using the LogoutHandlers configured in Spring Security. 
 See setLogoutHandlers(List).
 AsyncContext.start(Runnable) - Automatically copy the SecurityContext from the SecurityContextHolder found on the 
 Thread that invoked AsyncContext.start(Runnable) to the Thread that processes the Runnable.

11 KeycloakSecurityContextRequestFilter

RefreshableKeycloakSecurityContext --> refresh the Keycloak context ???

12 KeycloakAuthenticatedActionsFilter

13 AnonymousAuthenticationFilter

Detects if there is no Authentication object in the SecurityContextHolder, and populates it with one if needed. Populate it with a AnonymousAuthenticationToken for Anonymous Access

14 SessionManagementFilter

Detects that a user has been authenticated since the start of the request and, if they have, calls the configured SessionAuthenticationStrategy to perform any session-related activity such as activating session-fixation protection mechanisms or checking for multiple concurrent logins.

15 ExceptionTranslationFilter

Handles any AccessDeniedException and AuthenticationException thrown within the filter chain. This filter is necessary because it provides the bridge between Java exceptions and HTTP responses. It is solely concerned with maintaining the user interface. This filter does not do any actual security enforcement. If an AuthenticationException is detected, the filter will launch the authenticationEntryPoint. This allows common handling of authentication failures originating from any subclass of AbstractSecurityInterceptor. If an AccessDeniedException is detected, the filter will determine whether or not the user is an anonymous user. If they are an anonymous user, the authenticationEntryPoint will be launched. If they are not an anonymous user, the filter will delegate to the AccessDeniedHandler. By default the filter will use AccessDeniedHandlerImpl. To use this filter, it is necessary to specify the following properties:

 authenticationEntryPoint indicates the handler that should commence the authentication process if an 
 AuthenticationException is detected. Note that this may also switch the current protocol from http to https for an SSL login.
 requestCache determines the strategy used to save a request during the authentication process in order 
 that it may be retrieved and reused once the user has authenticated. The default implementation is HttpSessionRequestCache.

16 FilterSecurityInterceptor

Performs security handling of HTTP resources via a filter implementation. The SecurityMetadataSource required by this security interceptor is of type FilterInvocationSecurityMetadataSource. Refer to AbstractSecurityInterceptor for details on the workflow.

org.keycloak.adapters.PreAuthActionsHandler gets called in the org.keycloak.adapters.tomcat.AbstractKeycloakAuthenticatorValve before any Filters in Catalina Valves (StandardEngineValve --> ErrorReportValve)

Specific to keycloak handlers request with the:

• k_logout --> logout of keycloak (needs a valid JWT token)
• k_push_not_before --> Investigation needed (needs a valid JWT token)
• k_test_available --> Investigation needed
• k_jwks --> Investigatin needed

1. Load the (Keycloak) configuration known as the KeycloakDeployment from the application.yml file and from the Keycloak server.

2. Use the GET Token URL endpoint to obtain a AccessTokenResponse

Request: POST http://127.0.0.1:8080/auth/realms/example/protocol/openid-connect/token

Header: Content Type: application/x-www-form-urlencoded

Header: Authorization: Basic {clientId}:{clientSecret} This is read from the application.yml

Body: client_id=exampl-app-id&username=admin&password=94875l2&grant_type=password

Response:

{
  "access_token" : "eyJhbGciOiJSUzI1.....8aP1_iauQf-VpOchP70ADnnsfB54J8MAw5RQA0JaUCsBRHIsTMsowzadpERuvj3HvD7YScOQ",
  "expires_in" : 300,
  "refresh_expires_in" : 1800,
  "refresh_token" : "eyJhbGciOiJIUzI1NiIsInR5cCIgOiAiSldUIiwia2lkIiA.....0TC8em6dSPK6ISN-yvTHoOqXg8-l2pYYhyYQHUHlGhs",
  "token_type" : "bearer",
  "id_token" : null,
  "not-before-policy" : 0,
  "session_state" : "ec2905ce-7519-4678-bcc4-3d5a27731885",
  "scope" : "profile email" 
}

Value token returned -- needs to be decoded?

3. Register the session with keycloak & get identity (Refresh token)

4. Add token to session --> for subsequent request

5. Schedule Refresh

6. Logout handler for Session --> Back to keycloak

You can log out of a web application in multiple ways. For Java EE servlet containers, you can call HttpServletRequest.logout(). For other browser applications, you can redirect the browser to http://auth-server/auth/realms/{realm-name}/protocol/openid-connect/logout?redirect_uri=encodedRedirectUri, which logs you out if you have an SSO session with your browser.

7. Save session info --> browser