feat(config-server): add MongoDB environment repository support

This commit introduces MongoDB as a new backend option for the Spring Cloud Config Server, enabling users to store and manage their configuration properties in a MongoDB database.

spring-cloud-config-server/pom.xml

@@ -151,6 +151,11 @@
 			<artifactId>google-auth-library-oauth2-http</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-mongodb</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>com.h2database</groupId>
 			<artifactId>h2</artifactId>

spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/config/EnvironmentRepositoryConfiguration.java

@@ -68,6 +68,9 @@
 import org.springframework.cloud.config.server.environment.JdbcEnvironmentProperties;
 import org.springframework.cloud.config.server.environment.JdbcEnvironmentRepository;
 import org.springframework.cloud.config.server.environment.JdbcEnvironmentRepositoryFactory;
+import org.springframework.cloud.config.server.environment.MongoDbEnvironmentProperties;
+import org.springframework.cloud.config.server.environment.MongoDbEnvironmentRepository;
+import org.springframework.cloud.config.server.environment.MongoDbEnvironmentRepositoryFactory;
 import org.springframework.cloud.config.server.environment.MultipleJGitEnvironmentProperties;
 import org.springframework.cloud.config.server.environment.MultipleJGitEnvironmentRepository;
 import org.springframework.cloud.config.server.environment.MultipleJGitEnvironmentRepositoryFactory;
@@ -98,6 +101,7 @@
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.Environment;
 import org.springframework.credhub.core.CredHubOperations;
+import org.springframework.data.mongodb.core.MongoTemplate;
 import org.springframework.data.redis.core.StringRedisTemplate;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.vault.core.VaultTemplate;
@@ -111,19 +115,21 @@
  * @author Scott Frederick
  * @author Tejas Pandilwar
  * @author Iulian Antohe
+ * @author Alexandros Pappas
  */
 @Configuration(proxyBeanMethods = false)
 @EnableConfigurationProperties({ SvnKitEnvironmentProperties.class, CredhubEnvironmentProperties.class,
 		JdbcEnvironmentProperties.class, NativeEnvironmentProperties.class, VaultEnvironmentProperties.class,
 		RedisEnvironmentProperties.class, AwsS3EnvironmentProperties.class,
 		AwsSecretsManagerEnvironmentProperties.class, AwsParameterStoreEnvironmentProperties.class,
-		GoogleSecretManagerEnvironmentProperties.class })
+		GoogleSecretManagerEnvironmentProperties.class, MongoDbEnvironmentProperties.class })
 @Import({ CompositeRepositoryConfiguration.class, JdbcRepositoryConfiguration.class, VaultConfiguration.class,
 		VaultRepositoryConfiguration.class, SpringVaultRepositoryConfiguration.class, CredhubConfiguration.class,
 		CredhubRepositoryConfiguration.class, SvnRepositoryConfiguration.class, NativeRepositoryConfiguration.class,
 		GitRepositoryConfiguration.class, RedisRepositoryConfiguration.class, GoogleCloudSourceConfiguration.class,
 		AwsS3RepositoryConfiguration.class, AwsSecretsManagerRepositoryConfiguration.class,
 		AwsParameterStoreRepositoryConfiguration.class, GoogleSecretManagerRepositoryConfiguration.class,
+		MongoRepositoryConfiguration.class,
 		// DefaultRepositoryConfiguration must be last
 		DefaultRepositoryConfiguration.class })
 public class EnvironmentRepositoryConfiguration {
@@ -376,6 +382,19 @@ public NativeEnvironmentRepositoryFactory nativeEnvironmentRepositoryFactory(
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	@ConditionalOnClass(MongoTemplate.class)
+	@ConditionalOnProperty(value = "spring.cloud.config.server.mongodb.enabled", matchIfMissing = true)
+	static class MongoDbFactoryConfig {
+
+		@Bean
+		@ConditionalOnBean(MongoTemplate.class)
+		public MongoDbEnvironmentRepositoryFactory mongoDbEnvironmentRepositoryFactory(MongoTemplate mongoTemplate) {
+			return new MongoDbEnvironmentRepositoryFactory(mongoTemplate);
+		}
+
+	}
+
 }
 
 @Configuration(proxyBeanMethods = false)
@@ -577,3 +596,18 @@ public GoogleSecretManagerEnvironmentRepository googleSecretManagerEnvironmentRe
 	}
 
 }
+
+@Configuration(proxyBeanMethods = false)
+@Profile("mongodb")
+@ConditionalOnClass(MongoTemplate.class)
+@ConditionalOnProperty(value = "spring.cloud.config.server.mongodb.enabled", matchIfMissing = true)
+class MongoRepositoryConfiguration {
+
+	@Bean
+	@ConditionalOnBean(MongoTemplate.class)
+	public MongoDbEnvironmentRepository mongoDbEnvironmentRepository(MongoDbEnvironmentRepositoryFactory factory,
+			MongoDbEnvironmentProperties environmentProperties) {
+		return factory.build(environmentProperties);
+	}
+
+}

spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/MongoDbEnvironmentProperties.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2018-2019 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 org.springframework.cloud.config.server.environment;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.cloud.config.server.support.EnvironmentRepositoryProperties;
+import org.springframework.core.Ordered;
+
+/**
+ * Properties related to MongoDB environment repository.
+ *
+ * @author Alexandros Pappas
+ */
+@ConfigurationProperties("spring.cloud.config.server.mongodb")
+public class MongoDbEnvironmentProperties implements EnvironmentRepositoryProperties {
+
+	/**
+	 * Flag to indicate that MongoDB environment repository configuration is enabled.
+	 */
+	private boolean enabled = true;
+
+	/**
+	 * Order of the MongoDB environment repository.
+	 */
+	private int order = Ordered.LOWEST_PRECEDENCE - 10;
+
+	/**
+	 * Name of the MongoDB collection to query for configuration properties.
+	 */
+	private String collection = "properties";
+
+	/**
+	 * Flag to determine how to handle query exceptions.
+	 */
+	private boolean failOnError = true;
+
+	/**
+	 * Default label to use if none is specified.
+	 */
+	private String defaultLabel = "master";
+
+	public boolean isEnabled() {
+		return enabled;
+	}
+
+	public void setEnabled(boolean enabled) {
+		this.enabled = enabled;
+	}
+
+	public int getOrder() {
+		return order;
+	}
+
+	@Override
+	public void setOrder(int order) {
+		this.order = order;
+	}
+
+	public String getCollection() {
+		return collection;
+	}
+
+	public void setCollection(String collection) {
+		this.collection = collection;
+	}
+
+	public boolean isFailOnError() {
+		return failOnError;
+	}
+
+	public void setFailOnError(boolean failOnError) {
+		this.failOnError = failOnError;
+	}
+
+	public String getDefaultLabel() {
+		return defaultLabel;
+	}
+
+	public void setDefaultLabel(String defaultLabel) {
+		this.defaultLabel = defaultLabel;
+	}
+
+}

spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/MongoDbEnvironmentRepository.java

@@ -0,0 +1,128 @@
+/*
+ * Copyright 2018-2019 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 org.springframework.cloud.config.server.environment;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+import com.mongodb.MongoException;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.cloud.config.environment.Environment;
+import org.springframework.cloud.config.environment.PropertySource;
+import org.springframework.core.Ordered;
+import org.springframework.dao.DataAccessException;
+import org.springframework.data.mongodb.core.MongoTemplate;
+import org.springframework.data.mongodb.core.query.Criteria;
+import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.util.StringUtils;
+
+/**
+ * @author Alexandros Pappas
+ */
+public class MongoDbEnvironmentRepository implements EnvironmentRepository, Ordered {
+
+	private static final Log logger = LogFactory.getLog(JdbcEnvironmentRepository.class);
+
+	private final MongoTemplate mongoTemplate;
+
+	private final MongoDbEnvironmentProperties properties;
+
+	public MongoDbEnvironmentRepository(MongoTemplate mongoTemplate, MongoDbEnvironmentProperties properties) {
+		this.mongoTemplate = mongoTemplate;
+		this.properties = properties;
+	}
+
+	@Override
+	public Environment findOne(String application, String profile, String label) {
+		label = Optional.ofNullable(label).filter(StringUtils::hasText).orElse(this.properties.getDefaultLabel());
+		profile = Optional.ofNullable(profile).filter(StringUtils::hasText).orElse("default");
+
+		// Prepare the environment with applications and profiles
+		String[] profilesArray = StringUtils.commaDelimitedListToStringArray(profile);
+		Environment environment = new Environment(application, profilesArray, label, null, null);
+
+		// Prepend "application," to config if not already present
+		String config = application.startsWith("application") ? application : "application," + application;
+
+		List<String> applications = Arrays.stream(StringUtils.commaDelimitedListToStringArray(config)).distinct()
+				.collect(Collectors.toList());
+		List<String> profiles = Arrays.stream(profilesArray).distinct().collect(Collectors.toList());
+
+		// Reverse for the intended processing order
+		Collections.reverse(applications);
+		Collections.reverse(profiles);
+
+		// Add property sources for each combination of application and profile
+		for (String env : profiles) {
+			for (String app : applications) {
+				addPropertySource(environment, app, env, label);
+			}
+		}
+		// add properties without profile, equivalent to foo.yml, application.yml
+		for (String app : applications) {
+			addPropertySource(environment, app, null, label);
+		}
+		return environment;
+	}
+
+	private void addPropertySource(Environment environment, String application, String profile, String label) {
+		try {
+			Criteria criteria = Criteria.where("application").is(application).and("label").is(label);
+			if (profile != null) {
+				criteria = criteria.and("profile").is(profile);
+			}
+			else {
+				// Handling properties without profile by explicitly looking for them
+				criteria = criteria.andOperator(Criteria.where("profile").is(null));
+			}
+
+			Query query = new Query(criteria);
+			List<Map> propertyMaps = this.mongoTemplate.find(query, Map.class, this.properties.getCollection());
+
+			for (Map propertyMap : propertyMaps) {
+				String propertySourceName = (profile != null) ? application + "-" + profile : application;
+				@SuppressWarnings("unchecked")
+				Map<String, Object> source = (Map<String, Object>) propertyMap.get("properties");
+				if (source != null && !source.isEmpty()) {
+					environment.add(new PropertySource(propertySourceName, source));
+				}
+			}
+		}
+		catch (DataAccessException | MongoException e) {
+			if (!this.properties.isFailOnError()) {
+				if (logger.isDebugEnabled()) {
+					logger.debug("Failed to retrieve configuration from MongoDB", e);
+				}
+			}
+			else {
+				throw e;
+			}
+		}
+	}
+
+	@Override
+	public int getOrder() {
+		return this.properties.getOrder();
+	}
+
+}

spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/MongoDbEnvironmentRepositoryFactory.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2018-2019 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 org.springframework.cloud.config.server.environment;
+
+import org.springframework.data.mongodb.core.MongoTemplate;
+
+/**
+ * Factory for creating instances of MongoDbEnvironmentRepository.
+ *
+ * @author Alexandros Pappas
+ */
+public class MongoDbEnvironmentRepositoryFactory
+		implements EnvironmentRepositoryFactory<MongoDbEnvironmentRepository, MongoDbEnvironmentProperties> {
+
+	private final MongoTemplate mongoTemplate;
+
+	public MongoDbEnvironmentRepositoryFactory(MongoTemplate mongoTemplate) {
+		this.mongoTemplate = mongoTemplate;
+	}
+
+	@Override
+	public MongoDbEnvironmentRepository build(MongoDbEnvironmentProperties environmentProperties) {
+		return new MongoDbEnvironmentRepository(this.mongoTemplate, environmentProperties);
+	}
+
+}