Add How-to: Implement Multitenancy

Closes gh-663

docs/src/main/java/sample/multitenancy/RegisteredClientRepositoryConfig.java

@@ -0,0 +1,131 @@
+/*
+ * Copyright 2020-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package sample.multitenancy;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+
+import javax.sql.DataSource;
+
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.security.oauth2.core.AuthorizationGrantType;
+import org.springframework.security.oauth2.core.ClientAuthenticationMethod;
+import org.springframework.security.oauth2.server.authorization.client.JdbcRegisteredClientRepository;
+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.context.AuthorizationServerContextHolder;
+
+@Configuration(proxyBeanMethods = false)
+public class RegisteredClientRepositoryConfig {
+
+	@Bean
+	public RegisteredClientRepository registeredClientRepository(
+			@Qualifier("issuer1-data-source") DataSource issuer1DataSource,
+			@Qualifier("issuer2-data-source") DataSource issuer2DataSource) {
+
+		JdbcRegisteredClientRepository issuer1RegisteredClientRepository =
+				new JdbcRegisteredClientRepository(new JdbcTemplate(issuer1DataSource));	// <1>
+
+		// @fold:on
+		// @formatter:off
+		issuer1RegisteredClientRepository.save(
+				RegisteredClient.withId(UUID.randomUUID().toString())
+						.clientId("client-1")
+						.clientSecret("{noop}secret")
+						.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_BASIC)
+						.authorizationGrantType(AuthorizationGrantType.CLIENT_CREDENTIALS)
+						.scope("scope-1")
+						.build()
+		);
+		// @formatter:on
+		// @fold:off
+
+		JdbcRegisteredClientRepository issuer2RegisteredClientRepository =
+				new JdbcRegisteredClientRepository(new JdbcTemplate(issuer2DataSource));	// <2>
+
+		// @fold:on
+		// @formatter:off
+		issuer2RegisteredClientRepository.save(
+				RegisteredClient.withId(UUID.randomUUID().toString())
+						.clientId("client-2")
+						.clientSecret("{noop}secret")
+						.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_BASIC)
+						.authorizationGrantType(AuthorizationGrantType.CLIENT_CREDENTIALS)
+						.scope("scope-2")
+						.build()
+		);
+		// @formatter:on
+		// @fold:off
+
+		Map<String, RegisteredClientRepository> registeredClientRepositoryMap = new HashMap<>();
+		registeredClientRepositoryMap.put("issuer1", issuer1RegisteredClientRepository);
+		registeredClientRepositoryMap.put("issuer2", issuer2RegisteredClientRepository);
+
+		return new DelegatingRegisteredClientRepository(registeredClientRepositoryMap);
+	}
+
+	private static class DelegatingRegisteredClientRepository implements RegisteredClientRepository {	// <3>
+		private final Map<String, RegisteredClientRepository> registeredClientRepositoryMap;
+
+		private DelegatingRegisteredClientRepository(Map<String, RegisteredClientRepository> registeredClientRepositoryMap) {
+			this.registeredClientRepositoryMap = registeredClientRepositoryMap;
+		}
+
+		@Override
+		public void save(RegisteredClient registeredClient) {
+			RegisteredClientRepository registeredClientRepository = getRegisteredClientRepository();
+			if (registeredClientRepository != null) {
+				registeredClientRepository.save(registeredClient);
+			}
+		}
+
+		@Override
+		public RegisteredClient findById(String id) {
+			RegisteredClientRepository registeredClientRepository = getRegisteredClientRepository();
+			return (registeredClientRepository != null) ?
+					registeredClientRepository.findById(id) :
+					null;
+		}
+
+		@Override
+		public RegisteredClient findByClientId(String clientId) {
+			RegisteredClientRepository registeredClientRepository = getRegisteredClientRepository();
+			return (registeredClientRepository != null) ?
+					registeredClientRepository.findByClientId(clientId) :
+					null;
+		}
+
+		private RegisteredClientRepository getRegisteredClientRepository() {
+			if (AuthorizationServerContextHolder.getContext() == null ||
+					AuthorizationServerContextHolder.getContext().getIssuer() == null) {
+				return null;
+			}
+			String issuer = AuthorizationServerContextHolder.getContext().getIssuer();	// <4>
+			for (Map.Entry<String, RegisteredClientRepository> entry : this.registeredClientRepositoryMap.entrySet()) {
+				if (issuer.endsWith(entry.getKey())) {
+					return entry.getValue();
+				}
+			}
+			return null;
+		}
+
+	}
+
+}