The next step is to register the springSecurityFilterChain with the war. This can be done in Java Configuration with Spring’s WebApplicationInitializer support in a Servlet 3.0+ environment. Not suprisingly, Spring Security provides a base class AbstractSecurityWebApplicationInitializer that will ensure the springSecurityFilterChain gets registered for you. The way in which we use AbstractSecurityWebApplicationInitializer differs depending on if we are already using Spring or if Spring Security is the only Spring component in our application.

If you are not using Spring or Spring MVC, you will need to pass in the WebSecurityConfig into the superclass to ensure the configuration is picked up. You can find an example below:

import org.springframework.security.web.context.*;

public class SecurityWebApplicationInitializer
    extends AbstractSecurityWebApplicationInitializer {

    public SecurityWebApplicationInitializer() {
        super(WebSecurityConfig.class);
    }
}

The SecurityWebApplicationInitializer will do the following things:

If we were using Spring elsewhere in our application we probably already had a WebApplicationInitializer that is loading our Spring Configuration. If we use the previous configuration we would get an error. Instead, we should register Spring Security with the existing ApplicationContext. For example, if we were using Spring MVC our SecurityWebApplicationInitializer would look something like the following:

import org.springframework.security.web.context.*;

public class SecurityWebApplicationInitializer
    extends AbstractSecurityWebApplicationInitializer {

}

This would simply only register the springSecurityFilterChain Filter for every URL in your application. After that we would ensure that WebSecurityConfig was loaded in our existing ApplicationInitializer. For example, if we were using Spring MVC it would be added in the getRootConfigClasses()

public class MvcWebApplicationInitializer extends
        AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[] { WebSecurityConfig.class };
    }

    // ... other overrides ...
}

Generally, LogoutHandler implementations indicate classes that are able to participate in logout handling. They are expected to be invoked to perform necessary clean-up. As such they should not throw exceptions. Various implementations are provided:

Please see Section 10.5.4, “Remember-Me Interfaces and Implementations” for details.

Instead of providing LogoutHandler implementations directly, the fluent API also provides shortcuts that provide the respective LogoutHandler implementations under the covers. E.g. deleteCookies() allows specifying the names of one or more cookies to be removed on logout success. This is a shortcut compared to adding a CookieClearingLogoutHandler.

The LogoutSuccessHandler is called after a successful logout by the LogoutFilter, to handle e.g. redirection or forwarding to the appropriate destination. Note that the interface is almost the same as the LogoutHandler but may raise an exception.

The following implementations are provided:

As mentioned above, you don’t need to specify the SimpleUrlLogoutSuccessHandler directly. Instead, the fluent API provides a shortcut by setting the logoutSuccessUrl(). This will setup the SimpleUrlLogoutSuccessHandler under the covers. The provided URL will be redirected to after a logout has occurred. The default is /login?logout.

The HttpStatusReturningLogoutSuccessHandler can be interesting in REST API type scenarios. Instead of redirecting to a URL upon the successful logout, this LogoutSuccessHandler allows you to provide a plain HTTP status code to be returned. If not configured a status code 200 will be returned by default.

ClientRegistration is a representation of a client registered with an OAuth 2.0 or OpenID Connect 1.0 Provider.

A client registration holds information, such as client id, client secret, authorization grant type, redirect URI, scope(s), authorization URI, token URI, and other details.

ClientRegistration and its properties are defined as follows:

public final class ClientRegistration {
    private String registrationId;  
    private String clientId;    
    private String clientSecret;    
    private ClientAuthenticationMethod clientAuthenticationMethod;  
    private AuthorizationGrantType authorizationGrantType;  
    private String redirectUriTemplate; 
    private Set<String> scopes; 
    private ProviderDetails providerDetails;
    private String clientName;  

    public class ProviderDetails {
        private String authorizationUri;    
        private String tokenUri;    
        private UserInfoEndpoint userInfoEndpoint;
        private String jwkSetUri;   
        private Map<String, Object> configurationMetadata;  

        public class UserInfoEndpoint {
            private String uri; 
            private AuthenticationMethod authenticationMethod;  
            private String userNameAttributeName;   

        }
    }
}

The ClientRegistrationRepository serves as a repository for OAuth 2.0 / OpenID Connect 1.0 ClientRegistration(s).

	Note
	Client registration information is ultimately stored and owned by the associated Authorization Server. This repository provides the ability to retrieve a sub-set of the primary client registration information, which is stored with the Authorization Server.

Spring Boot 2.x auto-configuration binds each of the properties under spring.security.oauth2.client.registration.[registrationId] to an instance of ClientRegistration and then composes each of the ClientRegistration instance(s) within a ClientRegistrationRepository.

	Note
	The default implementation of ClientRegistrationRepository is InMemoryClientRegistrationRepository.

The auto-configuration also registers the ClientRegistrationRepository as a @Bean in the ApplicationContext so that it is available for dependency-injection, if needed by the application.

The following listing shows an example:

@Controller
public class OAuth2ClientController {

    @Autowired
    private ClientRegistrationRepository clientRegistrationRepository;

    @RequestMapping("/")
    public String index() {
        ClientRegistration googleRegistration =
            this.clientRegistrationRepository.findByRegistrationId("google");

        ...

        return "index";
    }
}

OAuth2AuthorizedClient is a representation of an Authorized Client. A client is considered to be authorized when the end-user (Resource Owner) has granted authorization to the client to access its protected resources.

OAuth2AuthorizedClient serves the purpose of associating an OAuth2AccessToken (and optional OAuth2RefreshToken) to a ClientRegistration (client) and resource owner, who is the Principal end-user that granted the authorization.

OAuth2AuthorizedClientRepository is responsible for persisting OAuth2AuthorizedClient(s) between web requests. Whereas, the primary role of OAuth2AuthorizedClientService is to manage OAuth2AuthorizedClient(s) at the application-level.

From a developer perspective, the OAuth2AuthorizedClientRepository or OAuth2AuthorizedClientService provides the capability to lookup an OAuth2AccessToken associated with a client so that it may be used to initiate a protected resource request.

	Note
	Spring Boot 2.x auto-configuration registers an OAuth2AuthorizedClientRepository and/or OAuth2AuthorizedClientService @Bean in the ApplicationContext.

The developer may also register an OAuth2AuthorizedClientRepository or OAuth2AuthorizedClientService @Bean in the ApplicationContext (overriding Spring Boot 2.x auto-configuration) in order to have the ability to lookup an OAuth2AccessToken associated with a specific ClientRegistration (client).

The following listing shows an example:

@Controller
public class OAuth2LoginController {

    @Autowired
    private OAuth2AuthorizedClientService authorizedClientService;

    @RequestMapping("/userinfo")
    public String userinfo(OAuth2AuthenticationToken authentication) {
        // authentication.getAuthorizedClientRegistrationId() returns the
        // registrationId of the Client that was authorized during the oauth2Login() flow
        OAuth2AuthorizedClient authorizedClient =
            this.authorizedClientService.loadAuthorizedClient(
                authentication.getAuthorizedClientRegistrationId(),
                authentication.getName());

        OAuth2AccessToken accessToken = authorizedClient.getAccessToken();

        ...

        return "userinfo";
    }
}

The @RegisteredOAuth2AuthorizedClient annotation provides the capability of resolving a method parameter to an argument value of type OAuth2AuthorizedClient. This is a convenient alternative compared to looking up the OAuth2AuthorizedClient via the OAuth2AuthorizedClientService.

@Controller
public class OAuth2LoginController {

    @RequestMapping("/userinfo")
    public String userinfo(@RegisteredOAuth2AuthorizedClient("google") OAuth2AuthorizedClient authorizedClient) {
        OAuth2AccessToken accessToken = authorizedClient.getAccessToken();

        ...

        return "userinfo";
    }
}

The @RegisteredOAuth2AuthorizedClient annotation is handled by OAuth2AuthorizedClientArgumentResolver and provides the following capabilities:

AuthorizationRequestRepository is responsible for the persistence of the OAuth2AuthorizationRequest from the time the Authorization Request is initiated to the time the Authorization Response is received (the callback).

	Tip
	The OAuth2AuthorizationRequest is used to correlate and validate the Authorization Response.

The default implementation of AuthorizationRequestRepository is HttpSessionOAuth2AuthorizationRequestRepository, which stores the OAuth2AuthorizationRequest in the HttpSession.

If you would like to provide a custom implementation of AuthorizationRequestRepository that stores the attributes of OAuth2AuthorizationRequest in a Cookie, you may configure it as shown in the following example:

@EnableWebSecurity
public class OAuth2ClientSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Client()
                .authorizationCodeGrant()
                    .authorizationRequestRepository(this.cookieAuthorizationRequestRepository())
                    ...
    }

    private AuthorizationRequestRepository<OAuth2AuthorizationRequest> cookieAuthorizationRequestRepository() {
        return new HttpCookieOAuth2AuthorizationRequestRepository();
    }
}

The primary role of the OAuth2AuthorizationRequestResolver is to resolve an OAuth2AuthorizationRequest from the provided web request. The default implementation DefaultOAuth2AuthorizationRequestResolver matches on the (default) path /oauth2/authorization/{registrationId} extracting the registrationId and using it to build the OAuth2AuthorizationRequest for the associated ClientRegistration.

One of the primary use cases an OAuth2AuthorizationRequestResolver can realize is the ability to customize the Authorization Request with additional parameters above the standard parameters defined in the OAuth 2.0 Authorization Framework.

For example, OpenID Connect defines additional OAuth 2.0 request parameters for the Authorization Code Flow extending from the standard parameters defined in the OAuth 2.0 Authorization Framework. One of those extended parameters is the prompt parameter.

	Note
	OPTIONAL. Space delimited, case sensitive list of ASCII string values that specifies whether the Authorization Server prompts the End-User for reauthentication and consent. The defined values are: none, login, consent, select_account

The following example shows how to implement an OAuth2AuthorizationRequestResolver that customizes the Authorization Request for oauth2Login(), by including the request parameter prompt=consent.

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private ClientRegistrationRepository clientRegistrationRepository;

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .oauth2Login()
                .authorizationEndpoint()
                    .authorizationRequestResolver(
                            new CustomAuthorizationRequestResolver(
                                    this.clientRegistrationRepository));    
    }
}

public class CustomAuthorizationRequestResolver implements OAuth2AuthorizationRequestResolver {
    private final OAuth2AuthorizationRequestResolver defaultAuthorizationRequestResolver;

    public CustomAuthorizationRequestResolver(
            ClientRegistrationRepository clientRegistrationRepository) {

        this.defaultAuthorizationRequestResolver =
                new DefaultOAuth2AuthorizationRequestResolver(
                        clientRegistrationRepository, "/oauth2/authorization");
    }

    @Override
    public OAuth2AuthorizationRequest resolve(HttpServletRequest request) {
        OAuth2AuthorizationRequest authorizationRequest =
                this.defaultAuthorizationRequestResolver.resolve(request);  

        return authorizationRequest != null ?   
                customAuthorizationRequest(authorizationRequest) :
                null;
    }

    @Override
    public OAuth2AuthorizationRequest resolve(
            HttpServletRequest request, String clientRegistrationId) {

        OAuth2AuthorizationRequest authorizationRequest =
                this.defaultAuthorizationRequestResolver.resolve(
                    request, clientRegistrationId);    

        return authorizationRequest != null ?   
                customAuthorizationRequest(authorizationRequest) :
                null;
    }

    private OAuth2AuthorizationRequest customAuthorizationRequest(
            OAuth2AuthorizationRequest authorizationRequest) {

        Map<String, Object> additionalParameters =
                new LinkedHashMap<>(authorizationRequest.getAdditionalParameters());
        additionalParameters.put("prompt", "consent");  

        return OAuth2AuthorizationRequest.from(authorizationRequest)    
                .additionalParameters(additionalParameters) 
                .build();
    }
}

	Tip
	OAuth2AuthorizationRequest.Builder.build() constructs the OAuth2AuthorizationRequest.authorizationRequestUri, which represents the complete Authorization Request URI including all query parameters using the application/x-www-form-urlencoded format.

The preceding example shows the common use case of adding a custom parameter on top of the standard parameters. However, if you need to remove or change a standard parameter or your requirements are more advanced, than you can take full control in building the Authorization Request URI by simply overriding the OAuth2AuthorizationRequest.authorizationRequestUri property.

The following example shows a variation of the customAuthorizationRequest() method from the preceding example, and instead overrides the OAuth2AuthorizationRequest.authorizationRequestUri property.

private OAuth2AuthorizationRequest customAuthorizationRequest(
        OAuth2AuthorizationRequest authorizationRequest) {

    String customAuthorizationRequestUri = UriComponentsBuilder
            .fromUriString(authorizationRequest.getAuthorizationRequestUri())
            .queryParam("prompt", "consent")
            .build(true)
            .toUriString();

    return OAuth2AuthorizationRequest.from(authorizationRequest)
            .authorizationRequestUri(customAuthorizationRequestUri)
            .build();
}

The primary role of the OAuth2AccessTokenResponseClient is to exchange an authorization grant credential for an access token credential at the Authorization Server’s Token Endpoint.

The default implementation of OAuth2AccessTokenResponseClient for the authorization_code grant is DefaultAuthorizationCodeTokenResponseClient, which uses a RestOperations for exchanging an authorization code for an access token at the Token Endpoint.

The DefaultAuthorizationCodeTokenResponseClient is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.

If you need to customize the pre-processing of the Token Request, you can provide DefaultAuthorizationCodeTokenResponseClient.setRequestEntityConverter() with a custom Converter<OAuth2AuthorizationCodeGrantRequest, RequestEntity<?>>. The default implementation OAuth2AuthorizationCodeGrantRequestEntityConverter builds a RequestEntity representation of a standard OAuth 2.0 Access Token Request. However, providing a custom Converter, would allow you to extend the standard Token Request and add a custom parameter for example.

	Important
	The custom Converter must return a valid RequestEntity representation of an OAuth 2.0 Access Token Request that is understood by the intended OAuth 2.0 Provider.

On the other end, if you need to customize the post-handling of the Token Response, you will need to provide DefaultAuthorizationCodeTokenResponseClient.setRestOperations() with a custom configured RestOperations. The default RestOperations is configured as follows:

RestTemplate restTemplate = new RestTemplate(Arrays.asList(
        new FormHttpMessageConverter(),
        new OAuth2AccessTokenResponseHttpMessageConverter()));

restTemplate.setErrorHandler(new OAuth2ErrorResponseErrorHandler());

	Tip
	Spring MVC FormHttpMessageConverter is required as it’s used when sending the OAuth 2.0 Access Token Request.

OAuth2AccessTokenResponseHttpMessageConverter is a HttpMessageConverter for an OAuth 2.0 Access Token Response. You can provide OAuth2AccessTokenResponseHttpMessageConverter.setTokenResponseConverter() with a custom Converter<Map<String, String>, OAuth2AccessTokenResponse> that is used for converting the OAuth 2.0 Access Token Response parameters to an OAuth2AccessTokenResponse.

OAuth2ErrorResponseErrorHandler is a ResponseErrorHandler that can handle an OAuth 2.0 Error (400 Bad Request). It uses an OAuth2ErrorHttpMessageConverter for converting the OAuth 2.0 Error parameters to an OAuth2Error.

Whether you customize DefaultAuthorizationCodeTokenResponseClient or provide your own implementation of OAuth2AccessTokenResponseClient, you’ll need to configure it as shown in the following example:

@EnableWebSecurity
public class OAuth2ClientSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .oauth2Client()
                .authorizationCodeGrant()
                    .accessTokenResponseClient(this.customAccessTokenResponseClient())
                    ...
    }

    private OAuth2AccessTokenResponseClient<OAuth2AuthorizationCodeGrantRequest> customAccessTokenResponseClient() {
        ...
    }
}

Spring Boot 2.x brings full auto-configuration capabilities for OAuth 2.0 Login.

This section shows how to configure the OAuth 2.0 Login sample using Google as the Authentication Provider and covers the following topics:

Initial setup

To use Google’s OAuth 2.0 authentication system for login, you must set up a project in the Google API Console to obtain OAuth 2.0 credentials.

	Note
	Google’s OAuth 2.0 implementation for authentication conforms to the OpenID Connect 1.0 specification and is OpenID Certified.

Follow the instructions on the OpenID Connect page, starting in the section, "Setting up OAuth 2.0".

After completing the "Obtain OAuth 2.0 credentials" instructions, you should have a new OAuth Client with credentials consisting of a Client ID and a Client Secret.

Setting the redirect URI

The redirect URI is the path in the application that the end-user’s user-agent is redirected back to after they have authenticated with Google and have granted access to the OAuth Client (created in the previous step) on the Consent page.

In the "Set a redirect URI" sub-section, ensure that the Authorized redirect URIs field is set to http://localhost:8080/login/oauth2/code/google.

	Tip
	The default redirect URI template is {baseUrl}/login/oauth2/code/{registrationId}. The registrationId is a unique identifier for the ClientRegistration.

The following table outlines the mapping of the Spring Boot 2.x OAuth Client properties to the ClientRegistration properties.

CommonOAuth2Provider pre-defines a set of default client properties for a number of well known providers: Google, GitHub, Facebook, and Okta.

For example, the authorization-uri, token-uri, and user-info-uri do not change often for a Provider. Therefore, it makes sense to provide default values in order to reduce the required configuration.

As demonstrated previously, when we configured a Google client, only the client-id and client-secret properties are required.

The following listing shows an example:

spring:
  security:
    oauth2:
      client:
        registration:
          google:
            client-id: google-client-id
            client-secret: google-client-secret

	Tip
	The auto-defaulting of client properties works seamlessly here because the registrationId (google) matches the GOOGLE enum (case-insensitive) in CommonOAuth2Provider.

For cases where you may want to specify a different registrationId, such as google-login, you can still leverage auto-defaulting of client properties by configuring the provider property.

The following listing shows an example:

spring:
  security:
    oauth2:
      client:
        registration:
          google-login: 
            provider: google    
            client-id: google-client-id
            client-secret: google-client-secret

There are some OAuth 2.0 Providers that support multi-tenancy, which results in different protocol endpoints for each tenant (or sub-domain).

For example, an OAuth Client registered with Okta is assigned to a specific sub-domain and have their own protocol endpoints.

For these cases, Spring Boot 2.x provides the following base property for configuring custom provider properties: spring.security.oauth2.client.provider.[providerId].

The following listing shows an example:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
        provider:
          okta: 
            authorization-uri: https://your-subdomain.oktapreview.com/oauth2/v1/authorize
            token-uri: https://your-subdomain.oktapreview.com/oauth2/v1/token
            user-info-uri: https://your-subdomain.oktapreview.com/oauth2/v1/userinfo
            user-name-attribute: sub
            jwk-set-uri: https://your-subdomain.oktapreview.com/oauth2/v1/keys

The Spring Boot 2.x auto-configuration class for OAuth Client support is OAuth2ClientAutoConfiguration.

It performs the following tasks:

If you need to override the auto-configuration based on your specific requirements, you may do so in the following ways:

@Configuration
public class OAuth2LoginConfig {

    @Bean
    public ClientRegistrationRepository clientRegistrationRepository() {
        return new InMemoryClientRegistrationRepository(this.googleClientRegistration());
    }

    private ClientRegistration googleClientRegistration() {
        return ClientRegistration.withRegistrationId("google")
            .clientId("google-client-id")
            .clientSecret("google-client-secret")
            .clientAuthenticationMethod(ClientAuthenticationMethod.BASIC)
            .authorizationGrantType(AuthorizationGrantType.AUTHORIZATION_CODE)
            .redirectUriTemplate("{baseUrl}/login/oauth2/code/{registrationId}")
            .scope("openid", "profile", "email", "address", "phone")
            .authorizationUri("https://accounts.google.com/o/oauth2/v2/auth")
            .tokenUri("https://www.googleapis.com/oauth2/v4/token")
            .userInfoUri("https://www.googleapis.com/oauth2/v3/userinfo")
            .userNameAttributeName(IdTokenClaimNames.SUB)
            .jwkSetUri("https://www.googleapis.com/oauth2/v3/certs")
            .clientName("Google")
            .build();
    }
}

@EnableWebSecurity
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .oauth2Login();
    }
}

@Configuration
public class OAuth2LoginConfig {

    @EnableWebSecurity
    public static class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

        @Override
        protected void configure(HttpSecurity http) throws Exception {
            http
                .authorizeRequests()
                    .anyRequest().authenticated()
                    .and()
                .oauth2Login();
        }
    }

    @Bean
    public ClientRegistrationRepository clientRegistrationRepository() {
        return new InMemoryClientRegistrationRepository(this.googleClientRegistration());
    }

    private ClientRegistration googleClientRegistration() {
        return ClientRegistration.withRegistrationId("google")
            .clientId("google-client-id")
            .clientSecret("google-client-secret")
            .clientAuthenticationMethod(ClientAuthenticationMethod.BASIC)
            .authorizationGrantType(AuthorizationGrantType.AUTHORIZATION_CODE)
            .redirectUriTemplate("{baseUrl}/login/oauth2/code/{registrationId}")
            .scope("openid", "profile", "email", "address", "phone")
            .authorizationUri("https://accounts.google.com/o/oauth2/v2/auth")
            .tokenUri("https://www.googleapis.com/oauth2/v4/token")
            .userInfoUri("https://www.googleapis.com/oauth2/v3/userinfo")
            .userNameAttributeName(IdTokenClaimNames.SUB)
            .jwkSetUri("https://www.googleapis.com/oauth2/v3/certs")
            .clientName("Google")
            .build();
    }
}

If you are not able to use Spring Boot 2.x and would like to configure one of the pre-defined providers in CommonOAuth2Provider (for example, Google), apply the following configuration:

@Configuration
public class OAuth2LoginConfig {

    @EnableWebSecurity
    public static class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {

        @Override
        protected void configure(HttpSecurity http) throws Exception {
            http
                .authorizeRequests()
                    .anyRequest().authenticated()
                    .and()
                .oauth2Login();
        }
    }

    @Bean
    public ClientRegistrationRepository clientRegistrationRepository() {
        return new InMemoryClientRegistrationRepository(this.googleClientRegistration());
    }

    @Bean
    public OAuth2AuthorizedClientService authorizedClientService(
            ClientRegistrationRepository clientRegistrationRepository) {
        return new InMemoryOAuth2AuthorizedClientService(clientRegistrationRepository);
    }

    @Bean
    public OAuth2AuthorizedClientRepository authorizedClientRepository(
            OAuth2AuthorizedClientService authorizedClientService) {
        return new AuthenticatedPrincipalOAuth2AuthorizedClientRepository(authorizedClientService);
    }

    private ClientRegistration googleClientRegistration() {
        return CommonOAuth2Provider.GOOGLE.getBuilder("google")
            .clientId("google-client-id")
            .clientSecret("google-client-secret")
            .build();
    }
}

The following additional resources describe advanced configuration options:

Most Resource Server support is collected into spring-security-oauth2-resource-server. However, the support for decoding and verifying JWTs is in spring-security-oauth2-jose, meaning that both are necessary in order to have a working resource server that supports JWT-encoded Bearer Tokens.

When using Spring Boot, configuring an application as a resource server consists of two basic steps. First, include the needed dependencies and second, indicate the location of the authorization server.

Specifying the Authorization Server

To specify which authorization server to use, simply do:

security:
  oauth2:
    resourceserver:
      jwt:
        issuer-uri: https://idp.example.com

Where https://idp.example.com is the value contained in the iss claim for JWT tokens that the authorization server will issue. Resource Server will use this property to further self-configure, discover the authorization server’s public keys, and subsequently validate incoming JWTs.

	Note
	To use the issuer-uri property, it must also be true that https://idp.example.com/.well-known/openid-configuration is a supported endpoint for the authorization server. This endpoint is referred to as a Provider Configuration endpoint.

And that’s it!

Startup Expectations

When this property and these dependencies are used, Resource Server will automatically configure itself to validate JWT-encoded Bearer Tokens.

It achieves this through a deterministic startup process:

1. Hit the Provider Configuration endpoint, https://idp.example.com/.well-known/openid-configuration, processing the response for the jwks_url property
2. Configure the validation strategy to query jwks_url for valid public keys
3. Configure the validation strategy to validate each JWTs iss claim against https://idp.example.com.

A consequence of this process is that the authorization server must be up and receiving requests in order for Resource Server to successfully start up.

	Note
	If the authorization server is down when Resource Server queries it (given appropriate timeouts), then startup will fail.

Runtime Expectations

Once the application is started up, Resource Server will attempt to process any request containing an Authorization: Bearer header:

GET / HTTP/1.1
Authorization: Bearer some-token-value # Resource Server will process this

So long as this scheme is indicated, Resource Server will attempt to process the request according to the Bearer Token specification.

Given a well-formed JWT token, Resource Server will

1. Validate its signature against a public key obtained from the jwks_url endpoint during startup and matched against the JWTs header
2. Validate the JWTs exp and nbf timestamps and the JWTs iss claim, and
3. Map each scope to an authority with the prefix SCOPE_.

	Note
	As the authorization server makes available new keys, Spring Security will automatically rotate the keys used to validate the JWT tokens.

The resulting Authentication#getPrincipal, by default, is a Spring Security Jwt object, and Authentication#getName maps to the JWT’s sub property, if one is present.

From here, consider jumping to:

How to Configure without Tying Resource Server startup to an authorization server’s availability

How to Configure without Spring Boot

If the authorization server doesn’t support the Provider Configuration endpoint, or if Resource Server must be able to start up independently from the authorization server, then issuer-uri can be exchanged for jwk-set-uri:

security:
  oauth2:
    resourceserver:
      jwt:
        jwk-set-uri: https://idp.example.com/.well-known/jwks.json

	Note
	The JWK Set uri is not standardized, but can typically be found in the authorization server’s documentation

Consequently, Resource Server will not ping the authorization server at startup. However, it will also no longer validate the iss claim in the JWT (since Resource Server no longer knows what the issuer value should be).

	Note
	This property can also be supplied directly on the DSL.

There are two @Bean s that Spring Boot generates on Resource Server’s behalf.

The first is a WebSecurityConfigurerAdapter that configures the app as a resource server:

protected void configure(HttpSecurity http) {
    http
        .authorizeRequests()
            .anyRequest().authenticated()
            .and()
        .oauth2ResourceServer()
            .jwt();
}

If the application doesn’t expose a WebSecurityConfigurerAdapter bean, then Spring Boot will expose the above default one.

Replacing this is as simple as exposing the bean within the application:

@EnableWebSecurity
public class MyCustomSecurityConfiguration extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .mvcMatchers("/messages/**").hasAuthority("SCOPE_message:read")
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .jwt()
                    .jwtAuthenticationConverter(myConverter());
    }
}

The above requires the scope of message:read for any URL that starts with /messages/.

Methods on the oauth2ResourceServer DSL will also override or replace auto configuration.

For example, the second @Bean Spring Boot creates is a JwtDecoder, which decodes String tokens into validated instances of Jwt:

@Bean
public JwtDecoder jwtDecoder() {
    return JwtDecoders.fromOidcIssuerLocation(issuerUri);
}

If the application doesn’t expose a JwtDecoder bean, then Spring Boot will expose the above default one.

And its configuration can be overridden using jwkSetUri() or replaced using decoder().

@EnableWebSecurity
public class DirectlyConfiguredJwkSetUri extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .jwt()
                    .jwkSetUri("https://idp.example.com/.well-known/jwks.json");
    }
}

@EnableWebSecurity
public class DirectlyConfiguredJwkSetUri extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .jwt()
                    .decoder(myCustomDecoder());
    }
}

@Bean
public JwtDecoder jwtDecoder() {
    return new NimbusJwtDecoder(JwtProcessors.withJwkSetUri(jwkSetUri).build());
}

A JWT that is issued from an OAuth 2.0 Authorization Server will typically either have a scope or scp attribute, indicating the scopes (or authorities) it’s been granted, for example:

{ …​, "scope" : "messages contacts"}

When this is the case, Resource Server will attempt to coerce these scopes into a list of granted authorities, prefixing each scope with the string "SCOPE_".

This means that to protect an endpoint or method with a scope derived from a JWT, the corresponding expressions should include this prefix:

@EnableWebSecurity
public class DirectlyConfiguredJwkSetUri extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .mvcMatchers("/contacts/**").hasAuthority("SCOPE_contacts")
                .mvcMatchers("/messages/**").hasAuthority("SCOPE_messages")
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .jwt();
    }
}

Or similarly with method security:

@PreAuthorize("hasAuthority('SCOPE_messages')")
public List<Message> getMessages(...) {}

@EnableWebSecurity
public class DirectlyConfiguredJwkSetUri extends WebSecurityConfigurerAdapter {
    protected void configure(HttpSecurity http) {
        http
            .authorizeRequests()
                .anyRequest().authenticated()
                .and()
            .oauth2ResourceServer()
                .jwt()
                    .jwtAuthenticationConverter(grantedAuthoritiesExtractor());
    }
}

Converter<Jwt, AbstractAuthenticationToken> grantedAuthoritiesExtractor() {
    return new GrantedAuthoritiesExtractor();
}

static class GrantedAuthoritiesExtractor extends JwtAuthenticationConverter {
    protected Collection<GrantedAuthorities> extractAuthorities(Jwt jwt) {
        Collection<String> authorities = (Collection<String>)
                jwt.getClaims().get("mycustomclaim");

        return authorities.stream()
                .map(SimpleGrantedAuthority::new)
                .collect(Collectors.toList());
    }
}

static class CustomAuthenticationConverter implements Converter<Jwt, AbstractAuthenticationToken> {
    public AbstractAuthenticationToken convert(Jwt jwt) {
        return new CustomAuthenticationToken(jwt);
    }
}

Using minimal Spring Boot configuration, indicating the authorization server’s issuer uri, Resource Server will default to verifying the iss claim as well as the exp and nbf timestamp claims.

In circumstances where validation needs to be customized, Resource Server ships with two standard validators and also accepts custom OAuth2TokenValidator instances.

Customizing Timestamp Validation

JWT’s typically have a window of validity, with the start of the window indicated in the nbf claim and the end indicated in the exp claim.

However, every server can experience clock drift, which can cause tokens to appear expired to one server, but not to another. This can cause some implementation heartburn as the number of collaborating servers increases in a distributed system.

Resource Server uses JwtTimestampValidator to verify a token’s validity window, and it can be configured with a clockSkew to alleviate the above problem:

@Bean
JwtDecoder jwtDecoder() {
     NimbusJwtDecoder jwtDecoder = (NimbusJwtDecoder)
             JwtDecoders.withOidcIssuerLocation(issuerUri);

     OAuth2TokenValidator<Jwt> withClockSkew = new DelegatingOAuth2TokenValidator<>(
            new JwtTimestampValidator(Duration.ofSeconds(60)),
            new IssuerValidator(issuerUri));

     jwtDecoder.setJwtValidator(withClockSkew);

     return jwtDecoder;
}

	Note
	By default, Resource Server configures a clock skew of 30 seconds.

public class AudienceValidator implements OAuth2TokenValidator<Jwt> {
    OAuth2Error error = new OAuth2Error("invalid_token", "The required audience is missing", null);

    public OAuth2TokenValidatorResult validate(Jwt jwt) {
        if (jwt.getAudience().contains("messaging")) {
            return OAuth2TokenValidatorResult.success();
        } else {
            return OAuth2TokenValidatorResult.failure(error);
        }
    }
}

@Bean
JwtDecoder jwtDecoder() {
    NimbusJwtDecoder jwtDecoder = (NimbusJwtDecoder)
        JwtDecoders.withOidcIssuerLocation(issuerUri);

    OAuth2TokenValidator<Jwt> audienceValidator = new AudienceValidator();
    OAuth2TokenValidator<Jwt> withIssuer = JwtValidators.createDefaultWithIssuer(issuerUri);
    OAuth2TokenValidator<Jwt> withAudience = new DelegatingOAuth2TokenValidator<>(withIssuer, audienceValidator);

    jwtDecoder.setJwtValidator(withAudience);

    return jwtDecoder;
}

Spring Security uses the Nimbus library for parsing JWTs and validating their signatures. Consequently, Spring Security is subject to Nimbus’s interpretation of each field value and how to coerce each into a Java type.

For example, because Nimbus remains Java 7 compatible, it doesn’t use Instant to represent timestamp fields.

And it’s entirely possible to use a different library or for JWT processing, which may make its own coercion decisions that need adjustment.

Or, quite simply, a resource server may want to add or remove claims from a JWT for domain-specific reasons.

For these purposes, Resource Server supports mapping the JWT claim set with MappedJwtClaimSetConverter.

@Bean
JwtDecoder jwtDecoder() {
    NimbusJwtDecoder jwtDecoder = new NimbusJwtDecoder(JwtProcessors.withJwkSetUri(jwkSetUri).build());

    MappedJwtClaimSetConverter converter = MappedJwtClaimSetConverter
            .withDefaults(Collections.singletonMap("sub", this::lookupUserIdBySub));
    jwtDecoder.setClaimSetConverter(converter);

    return jwtDecoder;
}

MappedJwtClaimSetConverter.withDefaults(Collections.singletonMap("custom", custom -> "value"));

MappedJwtClaimSetConverter.withDefaults(Collections.singletonMap("legacyclaim", legacy -> null));

public class UsernameSubClaimAdapter implements Converter<Map<String, Object>, Map<String, Object>> {
    private final MappedJwtClaimSetConverter delegate =
            MappedJwtClaimSetConverter.withDefaults(Collections.emptyMap());

    public Map<String, Object> convert(Map<String, Object> claims) {
        Map<String, Object> convertedClaims = this.delegate.convert(claims);

        String username = (String) convertedClaims.get("user_name");
        convertedClaims.put("sub", username);

        return convertedClaims;
    }
}

@Bean
JwtDecoder jwtDecoder() {
    NimbusJwtDecoder jwtDecoder = new NimbusJwtDecoder(JwtProcessors.withJwkSetUri(jwkSetUri).build());
    jwtDecoder.setClaimSetConverter(new UsernameSubClaimAdapter());
    return jwtDecoder;
}

By default, Resource Server uses connection and socket timeouts of 30 seconds each for coordinating with the authorization server.

This may be too short in some scenarios. Further, it doesn’t take into account more sophisticated patterns like back-off and discovery.

To adjust the way in which Resource Server connects to the authorization server, NimbusJwtDecoder accepts an instance of RestOperations:

@Bean
public JwtDecoder jwtDecoder(RestTemplateBuilder builder) {
    RestOperations rest = builder
            .setConnectionTimeout(60000)
            .setReadTimeout(60000)
            .build();

    NimbusJwtDecoder jwtDecoder = new NimbusJwtDecoder(JwtProcessors.withJwkSetUri(jwkSetUri).restOperations(rest).build());
    return jwtDecoder;
}

We have already seen an example of configuring in-memory authentication for a single user. Below is an example to configure multiple users:

@Bean
public UserDetailsService userDetailsService() throws Exception {
    // ensure the passwords are encoded properly
    UserBuilder users = User.withDefaultPasswordEncoder();
    InMemoryUserDetailsManager manager = new InMemoryUserDetailsManager();
    manager.createUser(users.username("user").password("password").roles("USER").build());
    manager.createUser(users.username("admin").password("password").roles("USER","ADMIN").build());
    return manager;
}

You can find the updates to support JDBC based authentication. The example below assumes that you have already defined a DataSource within your application. The jdbc-javaconfig sample provides a complete example of using JDBC based authentication.

@Autowired
private DataSource dataSource;

@Autowired
public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
    // ensure the passwords are encoded properly
    UserBuilder users = User.withDefaultPasswordEncoder();
    auth
        .jdbcAuthentication()
            .dataSource(dataSource)
            .withDefaultSchema()
            .withUser(users.username("user").password("password").roles("USER"))
            .withUser(users.username("admin").password("password").roles("USER","ADMIN"));
}

You can find the updates to support LDAP based authentication. The ldap-javaconfig sample provides a complete example of using LDAP based authentication.

@Autowired
private DataSource dataSource;

@Autowired
public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
    auth
        .ldapAuthentication()
            .userDnPatterns("uid={0},ou=people")
            .groupSearchBase("ou=groups");
}

The example above uses the following LDIF and an embedded Apache DS LDAP instance.

users.ldif. 

dn: ou=groups,dc=springframework,dc=org
objectclass: top
objectclass: organizationalUnit
ou: groups

dn: ou=people,dc=springframework,dc=org
objectclass: top
objectclass: organizationalUnit
ou: people

dn: uid=admin,ou=people,dc=springframework,dc=org
objectclass: top
objectclass: person
objectclass: organizationalPerson
objectclass: inetOrgPerson
cn: Rod Johnson
sn: Johnson
uid: admin
userPassword: password

dn: uid=user,ou=people,dc=springframework,dc=org
objectclass: top
objectclass: person
objectclass: organizationalPerson
objectclass: inetOrgPerson
cn: Dianne Emu
sn: Emu
uid: user
userPassword: password

dn: cn=user,ou=groups,dc=springframework,dc=org
objectclass: top
objectclass: groupOfNames
cn: user
uniqueMember: uid=admin,ou=people,dc=springframework,dc=org
uniqueMember: uid=user,ou=people,dc=springframework,dc=org

dn: cn=admin,ou=groups,dc=springframework,dc=org
objectclass: top
objectclass: groupOfNames
cn: admin
uniqueMember: uid=admin,ou=people,dc=springframework,dc=org

You can define custom authentication by exposing a custom AuthenticationProvider as a bean. For example, the following will customize authentication assuming that SpringAuthenticationProvider implements AuthenticationProvider:

	Note
	This is only used if the AuthenticationManagerBuilder has not been populated

@Bean
public SpringAuthenticationProvider springAuthenticationProvider() {
    return new SpringAuthenticationProvider();
}

You can define custom authentication by exposing a custom UserDetailsService as a bean. For example, the following will customize authentication assuming that SpringDataUserDetailsService implements UserDetailsService:

	Note
	This is only used if the AuthenticationManagerBuilder has not been populated and no AuthenticationProviderBean is defined.

@Bean
public SpringDataUserDetailsService springDataUserDetailsService() {
    return new SpringDataUserDetailsService();
}

You can also customize how passwords are encoded by exposing a PasswordEncoder as a bean. For example, if you use bcrypt you can add a bean definition as shown below:

@Bean
public BCryptPasswordEncoder passwordEncoder() {
    return new BCryptPasswordEncoder();
}

We can enable annotation-based security using the @EnableGlobalMethodSecurity annotation on any @Configuration instance. For example, the following would enable Spring Security’s @Secured annotation.

@EnableGlobalMethodSecurity(securedEnabled = true)
public class MethodSecurityConfig {
// ...
}

Adding an annotation to a method (on a class or interface) would then limit the access to that method accordingly. Spring Security’s native annotation support defines a set of attributes for the method. These will be passed to the AccessDecisionManager for it to make the actual decision:

public interface BankService {

@Secured("IS_AUTHENTICATED_ANONYMOUSLY")
public Account readAccount(Long id);

@Secured("IS_AUTHENTICATED_ANONYMOUSLY")
public Account[] findAccounts();

@Secured("ROLE_TELLER")
public Account post(Account account, double amount);
}

Support for JSR-250 annotations can be enabled using

@EnableGlobalMethodSecurity(jsr250Enabled = true)
public class MethodSecurityConfig {
// ...
}

These are standards-based and allow simple role-based constraints to be applied but do not have the power Spring Security’s native annotations. To use the new expression-based syntax, you would use

@EnableGlobalMethodSecurity(prePostEnabled = true)
public class MethodSecurityConfig {
// ...
}

and the equivalent Java code would be

public interface BankService {

@PreAuthorize("isAnonymous()")
public Account readAccount(Long id);

@PreAuthorize("isAnonymous()")
public Account[] findAccounts();

@PreAuthorize("hasAuthority('ROLE_TELLER')")
public Account post(Account account, double amount);
}

Sometimes you may need to perform operations that are more complicated than are possible with the @EnableGlobalMethodSecurity annotation allow. For these instances, you can extend the GlobalMethodSecurityConfiguration ensuring that the @EnableGlobalMethodSecurity annotation is present on your subclass. For example, if you wanted to provide a custom MethodSecurityExpressionHandler, you could use the following configuration:

@EnableGlobalMethodSecurity(prePostEnabled = true)
public class MethodSecurityConfig extends GlobalMethodSecurityConfiguration {
    @Override
    protected MethodSecurityExpressionHandler createExpressionHandler() {
        // ... create and return custom MethodSecurityExpressionHandler ...
        return expressionHandler;
    }
}

For additional information about methods that can be overridden, refer to the GlobalMethodSecurityConfiguration Javadoc.