If you are just getting started with Spring Authorization Server, the following sections walk you through creating your first application.

System Requirements

Spring Authorization Server requires a Java 17 or higher Runtime Environment.

Installing Spring Authorization Server

Spring Authorization Server can be used anywhere you already use Spring Security.

The easiest way to begin using Spring Authorization Server is by creating a Spring Boot-based application. You can use start.spring.io to generate a basic project or use the default authorization server sample as a guide. Then add Spring Authorization Server as a dependency, as in the following example:

Maven
<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-oauth2-authorization-server</artifactId>
    <version>1.0.7</version>
</dependency>
Gradle
implementation "org.springframework.security:spring-security-oauth2-authorization-server:1.0.7"
See Installing Spring Boot for more information on using Spring Boot with Maven or Gradle.

Developing Your First Application

To get started, you need the minimum required components defined as a @Bean in a Spring @Configuration. These components can be defined as follows:

To skip the setup and run a working example, see the default authorization server sample.
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.util.UUID;

import com.nimbusds.jose.jwk.JWKSet;
import com.nimbusds.jose.jwk.RSAKey;
import com.nimbusds.jose.jwk.source.ImmutableJWKSet;
import com.nimbusds.jose.jwk.source.JWKSource;
import com.nimbusds.jose.proc.SecurityContext;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;
import org.springframework.security.config.Customizer;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configurers.oauth2.server.resource.OAuth2ResourceServerConfigurer;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.oauth2.core.AuthorizationGrantType;
import org.springframework.security.oauth2.core.ClientAuthenticationMethod;
import org.springframework.security.oauth2.core.oidc.OidcScopes;
import org.springframework.security.oauth2.jwt.JwtDecoder;
import org.springframework.security.oauth2.server.authorization.client.InMemoryRegisteredClientRepository;
import org.springframework.security.oauth2.server.authorization.client.RegisteredClient;
import org.springframework.security.oauth2.server.authorization.client.RegisteredClientRepository;
import org.springframework.security.oauth2.server.authorization.config.annotation.web.configuration.OAuth2AuthorizationServerConfiguration;
import org.springframework.security.oauth2.server.authorization.config.annotation.web.configurers.OAuth2AuthorizationServerConfigurer;
import org.springframework.security.oauth2.server.authorization.settings.AuthorizationServerSettings;
import org.springframework.security.oauth2.server.authorization.settings.ClientSettings;
import org.springframework.security.provisioning.InMemoryUserDetailsManager;
import org.springframework.security.web.SecurityFilterChain;
import org.springframework.security.web.authentication.LoginUrlAuthenticationEntryPoint;

@Configuration
public class SecurityConfig {

	@Bean (1)
	@Order(1)
	public SecurityFilterChain authorizationServerSecurityFilterChain(HttpSecurity http)
			throws Exception {
		OAuth2AuthorizationServerConfiguration.applyDefaultSecurity(http);
		http.getConfigurer(OAuth2AuthorizationServerConfigurer.class)
			.oidc(Customizer.withDefaults());	// Enable OpenID Connect 1.0
		http
			// Redirect to the login page when not authenticated from the
			// authorization endpoint
			.exceptionHandling((exceptions) -> exceptions
				.authenticationEntryPoint(
					new LoginUrlAuthenticationEntryPoint("/login"))
			)
			// Accept access tokens for User Info and/or Client Registration
			.oauth2ResourceServer(OAuth2ResourceServerConfigurer::jwt);

		return http.build();
	}

	@Bean (2)
	@Order(2)
	public SecurityFilterChain defaultSecurityFilterChain(HttpSecurity http)
			throws Exception {
		http
			.authorizeHttpRequests((authorize) -> authorize
				.anyRequest().authenticated()
			)
			// Form login handles the redirect to the login page from the
			// authorization server filter chain
			.formLogin(Customizer.withDefaults());

		return http.build();
	}

	@Bean (3)
	public UserDetailsService userDetailsService() {
		UserDetails userDetails = User.withDefaultPasswordEncoder()
				.username("user")
				.password("password")
				.roles("USER")
				.build();

		return new InMemoryUserDetailsManager(userDetails);
	}

	@Bean (4)
	public RegisteredClientRepository registeredClientRepository() {
		RegisteredClient registeredClient = RegisteredClient.withId(UUID.randomUUID().toString())
				.clientId("messaging-client")
				.clientSecret("{noop}secret")
				.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_BASIC)
				.authorizationGrantType(AuthorizationGrantType.AUTHORIZATION_CODE)
				.authorizationGrantType(AuthorizationGrantType.REFRESH_TOKEN)
				.authorizationGrantType(AuthorizationGrantType.CLIENT_CREDENTIALS)
				.redirectUri("http://127.0.0.1:8080/login/oauth2/code/messaging-client-oidc")
				.redirectUri("http://127.0.0.1:8080/authorized")
				.scope(OidcScopes.OPENID)
				.scope(OidcScopes.PROFILE)
				.scope("message.read")
				.scope("message.write")
				.clientSettings(ClientSettings.builder().requireAuthorizationConsent(true).build())
				.build();

		return new InMemoryRegisteredClientRepository(registeredClient);
	}

	@Bean (5)
	public JWKSource<SecurityContext> jwkSource() {
		KeyPair keyPair = generateRsaKey();
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
		RSAKey rsaKey = new RSAKey.Builder(publicKey)
				.privateKey(privateKey)
				.keyID(UUID.randomUUID().toString())
				.build();
		JWKSet jwkSet = new JWKSet(rsaKey);
		return new ImmutableJWKSet<>(jwkSet);
	}

	private static KeyPair generateRsaKey() { (6)
		KeyPair keyPair;
		try {
			KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
			keyPairGenerator.initialize(2048);
			keyPair = keyPairGenerator.generateKeyPair();
		}
		catch (Exception ex) {
			throw new IllegalStateException(ex);
		}
		return keyPair;
	}

	@Bean (7)
	public JwtDecoder jwtDecoder(JWKSource<SecurityContext> jwkSource) {
		return OAuth2AuthorizationServerConfiguration.jwtDecoder(jwkSource);
	}

	@Bean (8)
	public AuthorizationServerSettings authorizationServerSettings() {
		return AuthorizationServerSettings.builder().build();
	}

}

This is a minimal configuration for getting started quickly. To understand what each component is used for, see the following descriptions:

1 A Spring Security filter chain for the Protocol Endpoints.
2 A Spring Security filter chain for authentication.
3 An instance of UserDetailsService for retrieving users to authenticate.
4 An instance of RegisteredClientRepository for managing clients.
5 An instance of com.nimbusds.jose.jwk.source.JWKSource for signing access tokens.
6 An instance of java.security.KeyPair with keys generated on startup used to create the JWKSource above.
7 An instance of JwtDecoder for decoding signed access tokens.
8 An instance of AuthorizationServerSettings to configure Spring Authorization Server.