This guide walks through the process to create a centralized authentication and authorization server with Spring Boot 2, a demo resource server will also be provided.

If you’re not familiar with OAuth2 I recommend this read.

Pre-req

JDK 1.8
Text editor or your favorite IDE
Maven 3.0+

Implementation Overview

For this project we’ll be using Spring Security 5 through Spring Boot. If you’re familiar with the earlier versions this Spring Boot Migration Guide might be useful.

OAuth2 Terminology

Resource Owner
- The user who authorizes an application to access his account. The access is limited to the scope.
Resource Server:
- A server that handles authenticated requests after the client has obtained an access token.
Client
- An application that access protected resources on behalf of the resource owner.
Authorization Server
- A server which issues access tokens after successfully authenticating a client and resource owner, and authorizing the request.
Access Token
- A unique token used to access protected resources
Scope
- A Permission
JWT
- JSON Web Token is a method for representing claims securely between two parties as defined in RFC 7519
Grant type
- A grant is a method of acquiring an access token.
- Read more about grant types here

Authorization Server

To build our Auth Server we’ll be using Spring Security 5.x through Spring Boot 2.1.x.

Dependencies

You can go to start.spring.io and generate a new project and then add the following dependencies:

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
		
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.security.oauth.boot</groupId>
            <artifactId>spring-security-oauth2-autoconfigure</artifactId>
            <version>2.1.2.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>		
    </dependencies>

Database

For the sake of this tutorial we’ll be using H2 Database.
Here you can find a reference OAuth2 SQL schema required by Spring Security.

CREATE TABLE IF NOT EXISTS oauth_client_details (
  client_id VARCHAR(256) PRIMARY KEY,
  resource_ids VARCHAR(256),
  client_secret VARCHAR(256) NOT NULL,
  scope VARCHAR(256),
  authorized_grant_types VARCHAR(256),
  web_server_redirect_uri VARCHAR(256),
  authorities VARCHAR(256),
  access_token_validity INTEGER,
  refresh_token_validity INTEGER,
  additional_information VARCHAR(4000),
  autoapprove VARCHAR(256)
);

CREATE TABLE IF NOT EXISTS oauth_client_token (
  token_id VARCHAR(256),
  token BLOB,
  authentication_id VARCHAR(256) PRIMARY KEY,
  user_name VARCHAR(256),
  client_id VARCHAR(256)
);

CREATE TABLE IF NOT EXISTS oauth_access_token (
  token_id VARCHAR(256),
  token BLOB,
  authentication_id VARCHAR(256),
  user_name VARCHAR(256),
  client_id VARCHAR(256),
  authentication BLOB,
  refresh_token VARCHAR(256)
);

CREATE TABLE IF NOT EXISTS oauth_refresh_token (
  token_id VARCHAR(256),
  token BLOB,
  authentication BLOB
);

CREATE TABLE IF NOT EXISTS oauth_code (
  code VARCHAR(256), authentication BLOB
);

Note: As this tutorial uses JWT not all the tables are required.

And then add the following entry

-- The encrypted client_secret it `secret`
INSERT INTO oauth_client_details (client_id, client_secret, scope, authorized_grant_types, authorities, access_token_validity)
  VALUES ('clientId', '{bcrypt}$2a$10$vCXMWCn7fDZWOcLnIEhmK.74dvK1Eh8ae2WrWlhr2ETPLoxQctN4.', 'read,write', 'password,refresh_token,client_credentials', 'ROLE_CLIENT', 300);

The client_secret above was generated using bcrypt.
The prefix {bcrypt} is required because we’ll using Spring Security 5.x’s new feature of DelegatingPasswordEncoder.

Bellow here you can find the User and Authority reference SQL schema used by Spring’s org.springframework.security.core.userdetails.jdbc.JdbcDaoImpl.

CREATE TABLE IF NOT EXISTS users (
  id INT AUTO_INCREMENT PRIMARY KEY,
  username VARCHAR(256) NOT NULL,
  password VARCHAR(256) NOT NULL,
  enabled TINYINT(1),
  UNIQUE KEY unique_username(username)
);

CREATE TABLE IF NOT EXISTS authorities (
  username VARCHAR(256) NOT NULL,
  authority VARCHAR(256) NOT NULL,
  PRIMARY KEY(username, authority)
);

Same as before add the following entries for the user and its authority.

-- The encrypted password is `pass`
INSERT INTO users (id, username, password, enabled) VALUES (1, 'user', '{bcrypt}$2a$10$cyf5NfobcruKQ8XGjUJkEegr9ZWFqaea6vjpXWEaSqTa2xL9wjgQC', 1);
INSERT INTO authorities (username, authority) VALUES ('user', 'ROLE_USER');

Spring Security Configuration

Add the following Spring configuration class.

import org.springframework.context.annotation.Bean;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.jdbc.JdbcDaoImpl;
import org.springframework.security.crypto.factory.PasswordEncoderFactories;
import org.springframework.security.crypto.password.PasswordEncoder;

import javax.sql.DataSource;

@EnableWebSecurity
public class WebSecurityConfiguration extends WebSecurityConfigurerAdapter {

    private final DataSource dataSource;

    private PasswordEncoder passwordEncoder;
    private UserDetailsService userDetailsService;

    public WebSecurityConfiguration(final DataSource dataSource) {
        this.dataSource = dataSource;
    }

    @Override
    protected void configure(final AuthenticationManagerBuilder auth) throws Exception {
        auth.userDetailsService(userDetailsService())
                .passwordEncoder(passwordEncoder());
    }

    @Bean
    @Override
    public AuthenticationManager authenticationManagerBean() throws Exception {
        return super.authenticationManagerBean();
    }

    @Bean
    public PasswordEncoder passwordEncoder() {
        if (passwordEncoder == null) {
            passwordEncoder = PasswordEncoderFactories.createDelegatingPasswordEncoder();
        }
        return passwordEncoder;
    }

    @Bean
    public UserDetailsService userDetailsService() {
        if (userDetailsService == null) {
            userDetailsService = new JdbcDaoImpl();
            ((JdbcDaoImpl) userDetailsService).setDataSource(dataSource);
        }
        return userDetailsService;
    }

}

Quoting from Spring Blog:

The @EnableWebSecurity annotation and WebSecurityConfigurerAdapter work together to provide web based security.

If you are using Spring Boot the DataSource object will be auto-configured and you can just inject it to the class instead of defining it yourself. it needs to be injected to the UserDetailsService in which will be using the provided JdbcDaoImpl provided by Spring Security, if necessary you can replace this with your own implementation.

As the Spring Security’s AuthenticationManager is required by some auto-configured Spring @Beans it’s necessary to override the authenticationManagerBean method and annotate is as a @Bean.

The PasswordEncoder will be handled by PasswordEncoderFactories.createDelegatingPasswordEncoder() in which handles a few of password encoders and delegates based on a prefix, in our example we are prefixing the passwords with {bcrypt}.

Authorization Server Configuration

The authorization server validates the client and user credentials and provides the tokens, in this tutorial we’ll be generating JSON Web Tokens a.k.a JWT.

To sign the generated JWT tokens we’ll be using a self-signed certificate and to do so before we start with the Spring Configuration let’s create a @ConfigurationProperties class to bind our configuration properties.

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.core.io.Resource;

@ConfigurationProperties("security")
public class SecurityProperties {

    private JwtProperties jwt;

    public JwtProperties getJwt() {
        return jwt;
    }

    public void setJwt(JwtProperties jwt) {
        this.jwt = jwt;
    }

    public static class JwtProperties {

        private Resource keyStore;
        private String keyStorePassword;
        private String keyPairAlias;
        private String keyPairPassword;

        public Resource getKeyStore() {
            return keyStore;
        }

        public void setKeyStore(Resource keyStore) {
            this.keyStore = keyStore;
        }

        public String getKeyStorePassword() {
            return keyStorePassword;
        }

        public void setKeyStorePassword(String keyStorePassword) {
            this.keyStorePassword = keyStorePassword;
        }

        public String getKeyPairAlias() {
            return keyPairAlias;
        }

        public void setKeyPairAlias(String keyPairAlias) {
            this.keyPairAlias = keyPairAlias;
        }

        public String getKeyPairPassword() {
            return keyPairPassword;
        }

        public void setKeyPairPassword(String keyPairPassword) {
            this.keyPairPassword = keyPairPassword;
        }
    }
}

Add the following Spring configuration class.

import com.marcosbarbero.lab.sec.oauth.jwt.config.props.SecurityProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.oauth2.config.annotation.configurers.ClientDetailsServiceConfigurer;
import org.springframework.security.oauth2.config.annotation.web.configuration.AuthorizationServerConfigurerAdapter;
import org.springframework.security.oauth2.config.annotation.web.configuration.EnableAuthorizationServer;
import org.springframework.security.oauth2.config.annotation.web.configurers.AuthorizationServerEndpointsConfigurer;
import org.springframework.security.oauth2.config.annotation.web.configurers.AuthorizationServerSecurityConfigurer;
import org.springframework.security.oauth2.provider.ClientDetailsService;
import org.springframework.security.oauth2.provider.token.DefaultTokenServices;
import org.springframework.security.oauth2.provider.token.TokenStore;
import org.springframework.security.oauth2.provider.token.store.JwtAccessTokenConverter;
import org.springframework.security.oauth2.provider.token.store.JwtTokenStore;
import org.springframework.security.oauth2.provider.token.store.KeyStoreKeyFactory;

import javax.sql.DataSource;
import java.security.KeyPair;

@Configuration
@EnableAuthorizationServer
@EnableConfigurationProperties(SecurityProperties.class)
public class AuthorizationServerConfiguration extends AuthorizationServerConfigurerAdapter {

    private final DataSource dataSource;
    private final PasswordEncoder passwordEncoder;
    private final AuthenticationManager authenticationManager;
    private final SecurityProperties securityProperties;
    private final UserDetailsService userDetailsService;

    private JwtAccessTokenConverter jwtAccessTokenConverter;
    private TokenStore tokenStore;

    public AuthorizationServerConfiguration(final DataSource dataSource, final PasswordEncoder passwordEncoder,
                                            final AuthenticationManager authenticationManager, final SecurityProperties securityProperties,
                                            final UserDetailsService userDetailsService) {
        this.dataSource = dataSource;
        this.passwordEncoder = passwordEncoder;
        this.authenticationManager = authenticationManager;
        this.securityProperties = securityProperties;
        this.userDetailsService = userDetailsService;
    }

    @Bean
    public TokenStore tokenStore() {
        if (tokenStore == null) {
            tokenStore = new JwtTokenStore(jwtAccessTokenConverter());
        }
        return tokenStore;
    }

    @Bean
    public DefaultTokenServices tokenServices(final TokenStore tokenStore,
                                              final ClientDetailsService clientDetailsService) {
        DefaultTokenServices tokenServices = new DefaultTokenServices();
        tokenServices.setSupportRefreshToken(true);
        tokenServices.setTokenStore(tokenStore);
        tokenServices.setClientDetailsService(clientDetailsService);
        tokenServices.setAuthenticationManager(this.authenticationManager);
        return tokenServices;
    }

    @Bean
    public JwtAccessTokenConverter jwtAccessTokenConverter() {
        if (jwtAccessTokenConverter != null) {
            return jwtAccessTokenConverter;
        }

        SecurityProperties.JwtProperties jwtProperties = securityProperties.getJwt();
        KeyPair keyPair = keyPair(jwtProperties, keyStoreKeyFactory(jwtProperties));

        jwtAccessTokenConverter = new JwtAccessTokenConverter();
        jwtAccessTokenConverter.setKeyPair(keyPair);
        return jwtAccessTokenConverter;
    }

    @Override
    public void configure(final ClientDetailsServiceConfigurer clients) throws Exception {
        clients.jdbc(this.dataSource);
    }

    @Override
    public void configure(final AuthorizationServerEndpointsConfigurer endpoints) {
        endpoints.authenticationManager(this.authenticationManager)
                .accessTokenConverter(jwtAccessTokenConverter())
                .userDetailsService(this.userDetailsService)
                .tokenStore(tokenStore());
    }

    @Override
    public void configure(final AuthorizationServerSecurityConfigurer oauthServer) {
        oauthServer.passwordEncoder(this.passwordEncoder).tokenKeyAccess("permitAll()")
                .checkTokenAccess("isAuthenticated()");
    }

    private KeyPair keyPair(SecurityProperties.JwtProperties jwtProperties, KeyStoreKeyFactory keyStoreKeyFactory) {
        return keyStoreKeyFactory.getKeyPair(jwtProperties.getKeyPairAlias(), jwtProperties.getKeyPairPassword().toCharArray());
    }

    private KeyStoreKeyFactory keyStoreKeyFactory(SecurityProperties.JwtProperties jwtProperties) {
        return new KeyStoreKeyFactory(jwtProperties.getKeyStore(), jwtProperties.getKeyStorePassword().toCharArray());
    }
}

In the class above you’ll find all the required Spring @Beans for JWT. The most important @Beans are: JwtAccessTokenConverter, JwtTokenStore and the DefaultTokenServices.

The JwtAccessTokenConverter uses the self-signed certificate to sign the generated tokens.
The JwtTokenStore implementation that just reads data from the tokens themselves. Not really a store since it never persists anything and it uses the JwtAccessTokenConverter to generate and read the tokens.
The DefaultTokenServices uses the TokenStore to persist the tokens.

Follow this guide to generate a self-signed certificate.

After generating your self-signed certificate configure it on your application.yml.

security:
  jwt:
    key-store: classpath:keystore.jks
    key-store-password: letmein
    key-pair-alias: mytestkey
    key-pair-password: changeme

Resource Server Configuration

The resource server hosts the HTTP resources in which can be a document a photo or something else, in our case it will be a REST API protected by OAuth2.

Dependencies

   <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
           
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.security.oauth.boot</groupId>
            <artifactId>spring-security-oauth2-autoconfigure</artifactId>
            <version>2.1.2.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>                
    </dependencies>

Defining our protected API

The code bellow defines the endpoint /me which returns the Principal object and it requires the authenticated user to have the ROLE_USER to access.

import org.springframework.http.ResponseEntity;
import org.springframework.security.access.prepost.PreAuthorize;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.security.Principal;

@RestController
@RequestMapping("/me")
public class UserController {

    @GetMapping
    @PreAuthorize("hasRole('ROLE_USER')")
    public ResponseEntity<Principal> get(final Principal principal) {
        return ResponseEntity.ok(principal);
    }

}

The @PreAuthorize annotation validates whether the user has the given role prior to execute the code, to make it work it’s necessary to enable the prePost annotations, to do so add the following class:

import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;

@EnableGlobalMethodSecurity(prePostEnabled = true)
public class WebSecurityConfiguration {

}

The important part here is the @EnableGlobalMethodSecurity(prePostEnabled = true) annotation, the prePostEnabled flag is set to false by default.

Resource Server Configuration

To decode the JWT token it will be necessary to use the public key from the self-signed certificated used on the Authorization Server to sign the token, to do so let’s first create a @ConfigurationProperties class to bind the configuration properties.

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.core.io.Resource;

@ConfigurationProperties("security")
public class SecurityProperties {

    private JwtProperties jwt;

    public JwtProperties getJwt() {
        return jwt;
    }

    public void setJwt(JwtProperties jwt) {
        this.jwt = jwt;
    }

    public static class JwtProperties {

        private Resource publicKey;

        public Resource getPublicKey() {
            return publicKey;
        }

        public void setPublicKey(Resource publicKey) {
            this.publicKey = publicKey;
        }
    }

}

Use the following command to export the public key from the generated JKS:

$ keytool -list -rfc --keystore keystore.jks | openssl x509 -inform pem -pubkey -noout

A sample response look like this:

Copy it to a public.txt file and place it at /src/main/resources and then configure your application.yml pointing to this file:

security:
  jwt:
    public-key: classpath:public.txt

Now let’s add the Spring’s configuration for the resource server.

import org.apache.commons.io.IOUtils;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.HttpMethod;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.oauth2.config.annotation.web.configuration.EnableResourceServer;
import org.springframework.security.oauth2.config.annotation.web.configuration.ResourceServerConfigurerAdapter;
import org.springframework.security.oauth2.config.annotation.web.configurers.ResourceServerSecurityConfigurer;
import org.springframework.security.oauth2.provider.token.DefaultTokenServices;
import org.springframework.security.oauth2.provider.token.TokenStore;
import org.springframework.security.oauth2.provider.token.store.JwtAccessTokenConverter;
import org.springframework.security.oauth2.provider.token.store.JwtTokenStore;

import java.io.IOException;

import static java.nio.charset.StandardCharsets.UTF_8;

@Configuration
@EnableResourceServer
@EnableConfigurationProperties(SecurityProperties.class)
public class ResourceServerConfiguration extends ResourceServerConfigurerAdapter {

    private static final String ROOT_PATTERN = "/**";

    private final SecurityProperties securityProperties;

    private TokenStore tokenStore;

    public ResourceServerConfiguration(final SecurityProperties securityProperties) {
        this.securityProperties = securityProperties;
    }

    @Override
    public void configure(final ResourceServerSecurityConfigurer resources) {
        resources.tokenStore(tokenStore());
    }

    @Override
    public void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests()
                .antMatchers(HttpMethod.GET, ROOT_PATTERN).access("#oauth2.hasScope('read')")
                .antMatchers(HttpMethod.POST, ROOT_PATTERN).access("#oauth2.hasScope('write')")
                .antMatchers(HttpMethod.PATCH, ROOT_PATTERN).access("#oauth2.hasScope('write')")
                .antMatchers(HttpMethod.PUT, ROOT_PATTERN).access("#oauth2.hasScope('write')")
                .antMatchers(HttpMethod.DELETE, ROOT_PATTERN).access("#oauth2.hasScope('write')");
    }

    @Bean
    public DefaultTokenServices tokenServices(final TokenStore tokenStore) {
        DefaultTokenServices tokenServices = new DefaultTokenServices();
        tokenServices.setTokenStore(tokenStore);
        return tokenServices;
    }

    @Bean
    public TokenStore tokenStore() {
        if (tokenStore == null) {
            tokenStore = new JwtTokenStore(jwtAccessTokenConverter());
        }
        return tokenStore;
    }

    @Bean
    public JwtAccessTokenConverter jwtAccessTokenConverter() {
        JwtAccessTokenConverter converter = new JwtAccessTokenConverter();
        converter.setVerifierKey(getPublicKeyAsString());
        return converter;
    }

    private String getPublicKeyAsString() {
        try {
            return IOUtils.toString(securityProperties.getJwt().getPublicKey().getInputStream(), UTF_8);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

}

The important part of this configuration are the three @Beans: JwtAccessTokenConverter, TokenStore and DefaultTokenServices:

The JwtAccessTokenConverter uses the JKS public key.
The JwtTokenStore uses the JwtAccessTokenConverter to read the tokens.
The DefaultTokenServices uses the JwtTokenStore to persist the tokens.

Testing all together

To test all together we need to spin up the Authorization Server and the Resource Server as well, in my setup it will be running on port 9000 and 9100 accordingly.

Generating the token

$ curl -u clientId:secret -X POST localhost:9000/oauth/token\?grant_type=password\&username=user\&password=pass

{
  "access_token" : "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE1NDgxODk0NDUsInVzZXJfbmFtZSI6InVzZXIiLCJhdXRob3JpdGllcyI6WyJST0xFX1VTRVIiXSwianRpIjoiYjFjYWQ3MTktZTkwMS00Njk5LTlhOWEtYTIwYzk2NDM5NjAzIiwiY2xpZW50X2lkIjoiY2xpZW50SWQiLCJzY29wZSI6WyJyZWFkIiwid3JpdGUiXX0.LkQ3KAj2kPY7yKmwXlhIFaHtt-31mJGWPb-_VpC8PWo9IBUpZQxg76WpahBJjet6O1ICx8b5Ab2CxH7ErTl0tL1jk5VZ_kp66E9E7bUQn-C09CY0fqxAan3pzpGrJsUvcR4pzyzLoRCuAqVRF5K2mdDQUZ8NaP0oXeVRuxyRdgjwMAkQGHpFC_Fk-7Hbsq2Y0GikD0UdkaH2Ey_vVyKy5aj3NrAZs62KFvQfSbifxd4uBHzUJSkiFE2Cx3u1xKs3W2q8MladwMwlQmWJROH6lDjQiybUZOEhJaktxQYGAinScnm11-9WOdaqohcr65PAQt48__rMRi0TUgvsxpz6ow",
  "token_type" : "bearer",
  "refresh_token" : "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyX25hbWUiOiJ1c2VyIiwic2NvcGUiOlsicmVhZCIsIndyaXRlIl0sImF0aSI6ImIxY2FkNzE5LWU5MDEtNDY5OS05YTlhLWEyMGM5NjQzOTYwMyIsImV4cCI6MTU1MDc4MTE0NSwiYXV0aG9yaXRpZXMiOlsiUk9MRV9VU0VSIl0sImp0aSI6Ijg2OWFjZjM2LTJiODAtNGY5Ni04MzUwLTA5NTgyMzE3NTAzMCIsImNsaWVudF9pZCI6ImNsaWVudElkIn0.TDQwUNb627-f0-Cjn1vWZXFpzZSGpeKZq85ivA9zY_atOXM2WfjOxTLE6phnNLevjLSNAGrx1skm_sx6leQlrrmDi36nwiR7lvhv8xMbn1DkF5KaoWPhldW7GHsSIiauMu_cJ5Kmq89ZOEOlxYoXlLwfWYo75ISkKNYqko98yDogGrRAJxtc1aKIBLypLchhoCf8w43efd11itwvBdaLIb5ACfN30kztUqQtbeL8voQP6tOsRZbCgbOOKMTulOCRyBvaora4GJDV2qdvXdCUT-kORKDj9liqt2ae7OJzb2FuuXCGqBUrxYYK-H-wdwh7XFkXVe74Lev9YDUbyEmDHg",
  "expires_in" : 299,
  "scope" : "read write",
  "jti" : "b1cad719-e901-4699-9a9a-a20c96439603"
}

Accessing the resource

Now that you have generated the token copy the access_token and add it to the request on the Authorization HTTP Header, e.g:

curl localhost:9100/me -H "Authorization: Bearer eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE1NDgxODk0NDUsInVzZXJfbmFtZSI6InVzZXIiLCJhdXRob3JpdGllcyI6WyJST0xFX1VTRVIiXSwianRpIjoiYjFjYWQ3MTktZTkwMS00Njk5LTlhOWEtYTIwYzk2NDM5NjAzIiwiY2xpZW50X2lkIjoiY2xpZW50SWQiLCJzY29wZSI6WyJyZWFkIiwid3JpdGUiXX0.LkQ3KAj2kPY7yKmwXlhIFaHtt-31mJGWPb-_VpC8PWo9IBUpZQxg76WpahBJjet6O1ICx8b5Ab2CxH7ErTl0tL1jk5VZ_kp66E9E7bUQn-C09CY0fqxAan3pzpGrJsUvcR4pzyzLoRCuAqVRF5K2mdDQUZ8NaP0oXeVRuxyRdgjwMAkQGHpFC_Fk-7Hbsq2Y0GikD0UdkaH2Ey_vVyKy5aj3NrAZs62KFvQfSbifxd4uBHzUJSkiFE2Cx3u1xKs3W2q8MladwMwlQmWJROH6lDjQiybUZOEhJaktxQYGAinScnm11-9WOdaqohcr65PAQt48__rMRi0TUgvsxpz6ow"

{
  "authorities" : [ {
    "authority" : "ROLE_GUEST"
  } ],
  "details" : {
    "remoteAddress" : "127.0.0.1",
    "sessionId" : null,
    "tokenValue" : "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE1NDgyMzcxNDEsInVzZXJfbmFtZSI6Imd1ZXN0IiwiYXV0aG9yaXRpZXMiOlsiUk9MRV9HVUVTVCJdLCJqdGkiOiIzNDk1ODE1MC0wOGJkLTQwMDYtYmNhMC1lM2RkYjAxMGU2NjUiLCJjbGllbnRfaWQiOiJjbGllbnRJZCIsInNjb3BlIjpbInJlYWQiLCJ3cml0ZSJdfQ.WUwAh-aKgh_Bqk-a9ijw67EI6H8gFrb3D_WdwlEcITskIybhacHjT6E7cUXjdBT7GCRvvJ-yxzFJIQyI6y0t61SInpqVG2GlAwtTxR5reG0e4ZtcKoq2rbQghK8hWenGplGT31kjDY78zZv-WqCAc0-MM4cC06fTXFzdhsdueY789lCasSD4WMMC6bWbN098lHF96rMpCdlW13EalrPgcKeuvZtUBrC8ntL8Bg3LRMcU1bFKTRAwlVxw1aYyqeEN4NSxkiSgQod2dltA-b3c15L-fXoOWNGnPB68hqgK48ymuemRQTSg3eKmHFAQdDL6pxQ8_D_ZWAL3QhsKQVGDKg",
    "tokenType" : "Bearer",
    "decodedDetails" : null
  },
  "authenticated" : true,
  "userAuthentication" : {
    "authorities" : [ {
      "authority" : "ROLE_GUEST"
    } ],
    "details" : null,
    "authenticated" : true,
    "principal" : "guest",
    "credentials" : "N/A",
    "name" : "guest"
  },
  "credentials" : "",
  "principal" : "guest",
  "clientOnly" : false,
  "oauth2Request" : {
    "clientId" : "clientId",
    "scope" : [ "read", "write" ],
    "requestParameters" : {
      "client_id" : "clientId"
    },
    "resourceIds" : [ ],
    "authorities" : [ ],
    "approved" : true,
    "refresh" : false,
    "redirectUri" : null,
    "responseTypes" : [ ],
    "extensions" : { },
    "grantType" : null,
    "refreshTokenRequest" : null
  },
  "name" : "guest"
}

Footnote

O código desse tutorial pode ser encontrado no GitHub
OAuth 2.0
Spring Security Java Config Preview
Spring Boot 2 - Guia de migração

Auth Server Centralizado com OAuth2 + JWT usando Spring Boot 2

Auth Server Centralizado com OAuth2 + JWT usando Spring Boot 2

Pre-req

Implementation Overview

OAuth2 Terminology

Authorization Server

Dependencies

Database

Spring Security Configuration

Authorization Server Configuration

Resource Server Configuration

Dependencies

Defining our protected API

Resource Server Configuration

Testing all together

Generating the token

Accessing the resource

Footnote