You can't use Keycloak adapters with spring-boot 3 for the reason you found, plus a few others related to transitive dependencies. As most Keycloak adapters were deprecated in early 2022, it is very likely that no update will be published to fix that.
Instead, use spring-security 6 libs for OAuth2. Don't panic, it's an easy task with spring-boot.
In the following, I'll consider you have a good understanding of OAuth2 concepts and know exactly why you need to configure an OAuth2 client or an OAuth2 resource server. In case of doubt, please refer to the OAuth2 essentials section of my tutorials.
I'll only detail here the configuration of servlet application as a resource server, and then as a client, for a single Keycloak realm, with and then without spring-addons-starter-oidc, a Spring Boot starter of mine. Browse directly to the section you are interested in (but be prepared to write much more code if you don't want to use "my" starter).
Also refer to my tutorials for different use-cases like:
- accepting tokens issued by multiple realms or instances (known in advance or dynamically created in a trusted domain)
- reactive applications (webflux), like
spring-cloud-gateway for instance
- apps publicly serving both a REST API and a server-side rendered UI to consume it
- advanced access-control rules
- BFF pattern
- ...
1. OAuth2 Resource Server
App exposes a REST API secured with access tokens. It is consumed by an OAuth2 REST client. A few sample of such clients:
- another Spring application configured as an OAuth2 client and using
WebClient, @FeignClient, RestTemplate or alike
- development tools like Postman capable of fetching OAuth2 tokens and issuing REST requests
- Javascript based application configured as a "public" OAuth2 client with a library like angular-auth-oidc-client
1.1. With spring-addons-starter-oidc
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-oauth2-resource-server</artifactId>
</dependency>
<dependency>
<groupId>com.c4-soft.springaddons</groupId>
<artifactId>spring-addons-starter-oidc</artifactId>
<version>7.1.3</version>
</dependency>
origins: http://localhost:4200
issuer: http://localhost:8442/realms/master
com:
c4-soft:
springaddons:
oidc:
ops:
- iss: ${issuer}
username-claim: preferred_username
authorities:
- path: $.realm_access.roles
prefix: ROLE_
- path: $.resource_access.*.roles
resourceserver:
cors:
- path: /**
allowed-origin-patterns: ${origins}
permit-all:
- "/actuator/health/readiness"
- "/actuator/health/liveness"
- "/v3/api-docs/**"
Prefix for realm roles in the conf above are there only for illustration purposes, you might remove it. The CORS configuration would need some refinements too.
@Configuration
@EnableMethodSecurity
public static class WebSecurityConfig { }
Nothing more is needed to configure a resource-server with fine tuned CORS policy and authorities mapping. Bootiful, isn't it?.
As you can guess from the ops property being an array, this solution is actually compatible with "static" multi-tenancy: you can declare as many trusted issuers as you need and it can be heterogeneous (use different claims for username and authorities).
Also, this solution is compatible with reactive application: spring-addons-starter-oidc will detect it from what is on the class-path and adapt its security auto-configuration.
1.2. With just spring-boot-starter-oauth2-resource-server
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-oauth2-resource-server</artifactId>
</dependency>
<dependency>
<!-- used when converting Keycloak roles to Spring authorities -->
<groupId>com.jayway.jsonpath</groupId>
<artifactId>json-path</artifactId>
</dependency>
spring:
security:
oauth2:
resourceserver:
jwt:
issuer-uri: http://localhost:8442/realms/master
@Configuration
@EnableWebSecurity
@EnableMethodSecurity
public static class WebSecurityConfig {
@Bean
SecurityFilterChain filterChain(HttpSecurity http, Converter<Jwt, ? extends AbstractAuthenticationToken> jwtAuthenticationConverter) throws Exception {
http.oauth2ResourceServer(oauth2 -> oauth2.jwt(jwt -> jwt.jwtAuthenticationConverter(jwtAuthenticationConverter)));
// Enable and configure CORS
http.cors(cors -> cors.configurationSource(corsConfigurationSource("http://localhost:4200")));
// State-less session (state in access-token only)
http.sessionManagement(sm -> sm.sessionCreationPolicy(SessionCreationPolicy.STATELESS));
// Disable CSRF because of state-less session-management
http.csrf(csrf -> csrf.disable());
// Return 401 (unauthorized) instead of 302 (redirect to login) when
// authorization is missing or invalid
http.exceptionHandling(eh -> eh.authenticationEntryPoint((request, response, authException) -> {
response.addHeader(HttpHeaders.WWW_AUTHENTICATE, "Bearer realm=\"Restricted Content\"");
response.sendError(HttpStatus.UNAUTHORIZED.value(), HttpStatus.UNAUTHORIZED.getReasonPhrase());
}));
// @formatter:off
http.authorizeHttpRequests(accessManagement -> accessManagement
.requestMatchers("/actuator/health/readiness", "/actuator/health/liveness", "/v3/api-docs/**").permitAll()
.anyRequest().authenticated()
);
// @formatter:on
return http.build();
}
private UrlBasedCorsConfigurationSource corsConfigurationSource(String... origins) {
final var configuration = new CorsConfiguration();
configuration.setAllowedOrigins(Arrays.asList(origins));
configuration.setAllowedMethods(List.of("*"));
configuration.setAllowedHeaders(List.of("*"));
configuration.setExposedHeaders(List.of("*"));
final var source = new UrlBasedCorsConfigurationSource();
source.registerCorsConfiguration("/**", configuration);
return source;
}
@RequiredArgsConstructor
static class JwtGrantedAuthoritiesConverter implements Converter<Jwt, Collection<? extends GrantedAuthority>> {
@Override
@SuppressWarnings({ "rawtypes", "unchecked" })
public Collection<? extends GrantedAuthority> convert(Jwt jwt) {
return Stream.of("$.realm_access.roles", "$.resource_access.*.roles").flatMap(claimPaths -> {
Object claim;
try {
claim = JsonPath.read(jwt.getClaims(), claimPaths);
} catch (PathNotFoundException e) {
claim = null;
}
if (claim == null) {
return Stream.empty();
}
if (claim instanceof String claimStr) {
return Stream.of(claimStr.split(","));
}
if (claim instanceof String[] claimArr) {
return Stream.of(claimArr);
}
if (Collection.class.isAssignableFrom(claim.getClass())) {
final var iter = ((Collection) claim).iterator();
if (!iter.hasNext()) {
return Stream.empty();
}
final var firstItem = iter.next();
if (firstItem instanceof String) {
return (Stream<String>) ((Collection) claim).stream();
}
if (Collection.class.isAssignableFrom(firstItem.getClass())) {
return (Stream<String>) ((Collection) claim).stream().flatMap(colItem -> ((Collection) colItem).stream()).map(String.class::cast);
}
}
return Stream.empty();
})
/* Insert some transformation here if you want to add a prefix like "ROLE_" or force upper-case authorities */
.map(SimpleGrantedAuthority::new)
.map(GrantedAuthority.class::cast).toList();
}
}
@Component
@RequiredArgsConstructor
static class SpringAddonsJwtAuthenticationConverter implements Converter<Jwt, JwtAuthenticationToken> {
@Override
public JwtAuthenticationTokenconvert(Jwt jwt) {
final var authorities = new JwtGrantedAuthoritiesConverter().convert(jwt);
final String username = JsonPath.read(jwt.getClaims(), "preferred_username");
return new JwtAuthenticationToken(jwt, authorities, username);
}
}
}
In addition to being much more verbose than preceding one, this solution is also less flexible:
- not adapted to multi-tenancy (multiple Keycloak realms or instances)
- hardcoded allowed origins
- hardcoded claim names to fetch autorities from
- hardcoded "permitAll" path matchers
2. OAuth2 Client
App exposes any kind of resources secured with sessions (not access tokens). It is consumed directly by a browser (or any other user agent capable of maintaining a session) without the need of a scripting language or OAuth2 client lib (authorization-code flow, logout and token storage are handled by Spring on the server). Common uses-cases are:
- applications with server-side rendered UI (with Thymeleaf, JSF, or whatever)
spring-cloud-gateway used as Backend For Frontend: configured as OAuth2 client with TokenRelay filter (hides OAuth2 tokens from the browser and replaces session cookie with an access token before forwarding a request to downstream resource server(s))
Note that the Back-Channel Logout is not implemented by Spring yet. If you need it, use "my" starters (or copy from it).
2.1. With spring-addons-starter-oidc
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-client</artifactId>
</dependency>
<dependency>
<groupId>com.c4-soft.springaddons</groupId>
<artifactId>spring-addons-starter-oidc</artifactId>
<version>7.1.3</version>
</dependency>
issuer: http://localhost:8442/realms/master
client-id: spring-addons-confidential
client-secret: change-me
client-uri: http://localhost:8080
spring:
security:
oauth2:
client:
provider:
keycloak:
issuer-uri: ${issuer}
registration:
keycloak-login:
authorization-grant-type: authorization_code
client-name: My Keycloak instance
client-id: ${client-id}
client-secret: ${client-secret}
provider: keycloak
scope: openid,profile,email,offline_access
com:
c4-soft:
springaddons:
oidc:
ops:
- iss: ${issuer}
username-claim: preferred_username
authorities:
- path: $.realm_access.roles
- path: $.resource_access.*.roles
client:
client-uri: ${client-uri}
security-matchers: /**
permit-all:
- /
- /login/**
- /oauth2/**
csrf: cookie-accessible-from-js
post-login-redirect-path: /home
post-logout-redirect-path: /
back-channel-logout-enabled: true
@Configuration
@EnableMethodSecurity
public class WebSecurityConfig {
}
As for resource server, this solution works in reactive applications too.
There is also an optional support for multi-tenancy on clients: allow a user to be logged in simultaneously on several OpenID Providers, on which he might have different usernames (subject by default, which is a UUID in Keycloak, and changes with each realm).
2.2. With just spring-boot-starter-oauth2-client
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-oauth2-client</artifactId>
</dependency>
<dependency>
<!-- used when converting Keycloak roles to Spring authorities -->
<groupId>com.jayway.jsonpath</groupId>
<artifactId>json-path</artifactId>
</dependency>
issuer: http://localhost:8442/realms/master
client-id: spring-addons-confidential
client-secret: change-me
spring:
security:
oauth2:
client:
provider:
keycloak:
issuer-uri: ${issuer}
registration:
keycloak-login:
authorization-grant-type: authorization_code
client-name: My Keycloak instance
client-id: ${client-id}
client-secret: ${client-secret}
provider: keycloak
scope: openid,profile,email,offline_access
@Configuration
@EnableWebSecurity
@EnableMethodSecurity
public class WebSecurityConfig {
@Bean
SecurityFilterChain
clientSecurityFilterChain(HttpSecurity http, InMemoryClientRegistrationRepository clientRegistrationRepository)
throws Exception {
http.oauth2Login(withDefaults());
http.logout(logout -> {
logout.logoutSuccessHandler(new OidcClientInitiatedLogoutSuccessHandler(clientRegistrationRepository));
});
// @formatter:off
http.authorizeHttpRequests(ex -> ex
.requestMatchers("/", "/login/**", "/oauth2/**").permitAll()
.requestMatchers("/nice.html").hasAuthority("NICE")
.anyRequest().authenticated());
// @formatter:on
return http.build();
}
@Component
@RequiredArgsConstructor
static class GrantedAuthoritiesMapperImpl implements GrantedAuthoritiesMapper {
@Override
public Collection<? extends GrantedAuthority> mapAuthorities(Collection<? extends GrantedAuthority> authorities) {
Set<GrantedAuthority> mappedAuthorities = new HashSet<>();
authorities.forEach(authority -> {
if (OidcUserAuthority.class.isInstance(authority)) {
final var oidcUserAuthority = (OidcUserAuthority) authority;
final var issuer = oidcUserAuthority.getIdToken().getClaimAsURL(JwtClaimNames.ISS);
mappedAuthorities.addAll(extractAuthorities(oidcUserAuthority.getIdToken().getClaims()));
} else if (OAuth2UserAuthority.class.isInstance(authority)) {
try {
final var oauth2UserAuthority = (OAuth2UserAuthority) authority;
final var userAttributes = oauth2UserAuthority.getAttributes();
final var issuer = new URL(userAttributes.get(JwtClaimNames.ISS).toString());
mappedAuthorities.addAll(extractAuthorities(userAttributes));
} catch (MalformedURLException e) {
throw new RuntimeException(e);
}
}
});
return mappedAuthorities;
};
@SuppressWarnings({ "rawtypes", "unchecked" })
private static Collection<GrantedAuthority> extractAuthorities(Map<String, Object> claims) {
/* See resource server solution above for authorities mapping */
}
}
}
This starter is a standard Spring Boot starter with additional application properties used to auto-configure default beans and provide it to Spring Security. It is important to note that the auto-configured @Beans are almost all @ConditionalOnMissingBean which enables you to override it in your conf.
It is open-source and you can change everything it pre-configures for you (refer to the Javadoc, the starter READMEs, or the many samples). You should read the starters source before deciding not to trust it, it is not that big. Start with imports resource, it defines what is loaded by Spring Boot for auto-configuration.
In my opinion (and as demonstrated above), Spring Boot auto-configuration for OAuth2 can be pushed one step further to:
- make OAuth2 configuration more portable: with a configurable authorities converter, switching from an OIDC provider to another is just a matter of editing properties (Keycloak, Auth0, Cognito, Azure AD, etc.)
- ease app deployment on different environments: CORS configuration is controlled from properties file
- reduce drastically the amount of Java code (things get even more complicated if you are in multi-tenancy scenario)
- support more than just one issuer by default
- reduce chances of misconfiguration (for instance, it is frequent to see sample configurations with disabled CSRF protection on clients, or wasting resources with sessions on endpoints secured with access tokens)
