Add a ConfigResourceClient for plain text and binary files

docs/modules/ROOT/pages/client.adoc

@@ -138,6 +138,25 @@ Label can also be provided as a comma-separated list.
 This behavior can be useful when working on a feature branch.
 For instance, you might want to align the config label with your branch but make it optional (in that case, use `spring.cloud.config.label=myfeature,develop`).
 
+[[reading-plain-text-and-binary-files]]
+== Reading Plain Text and Binary Files
+
+The Config Server can also serve plain text and binary files from the configuration repository (see xref:server/serving-plain-text.adoc[Serving Plain Text] and xref:server/serving-binary-files.adoc[Serving Binary Files]).
+When the configuration is imported with `spring.config.import=configserver:`, the client registers a `ConfigResourceClient` bean that reads such files with the same settings that loaded the configuration (URI, credentials, headers, TLS settings, timeouts and token), as the following example shows:
+
+[source,java]
+----
+@Autowired
+private ConfigResourceClient configResourceClient;
+
+Resource nginx = configResourceClient.getPlainTextResource("nginx.conf");
+Resource logo = configResourceClient.getBinaryResource("dev", "main", "images/logo.png");
+----
+
+Without a profile or label, the client uses `spring.cloud.config.profile` and `spring.cloud.config.label`; without a label, the server's default label is used.
+Like the import, it tries each configured URI according to `spring.cloud.config.multiple-uri-strategy`, with the credentials of that URI, and tries a comma-separated label one label at a time.
+A file is read into memory, so a file larger than `spring.cloud.config.resource-client.max-size` (1MB by default) is rejected; `0` disables the limit.
+
 [[sharing-configuration-across-applications]]
 == Sharing Configuration Across Applications
 

docs/modules/ROOT/partials/_configprops.adoc

@@ -19,6 +19,7 @@
 |spring.cloud.config.profile | `+++default+++` | The default profile to use when fetching remote configuration (comma-separated). Default is "default".
 |spring.cloud.config.request-connect-timeout |  | timeout on waiting to connect to the Config Server.
 |spring.cloud.config.request-read-timeout |  | timeout on waiting to read data from the Config Server.
+|spring.cloud.config.resource-client.max-size | `+++1MB+++` | Maximum size of a file read from the config server; a larger file is rejected instead of being loaded into memory. Zero disables the limit.
 |spring.cloud.config.retry.enabled | `+++false+++` | Whether to retry failed requests to the Config Server. Only has an effect when spring.cloud.config.fail-fast is enabled.
 |spring.cloud.config.retry.initial-interval | `+++1000+++` | Initial retry interval in milliseconds.
 |spring.cloud.config.retry.max-attempts | `+++6+++` | Maximum number of attempts.

spring-cloud-config-client/src/main/java/org/springframework/cloud/config/client/BinaryResourceConfigClient.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2013-present 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.client;
+
+import org.springframework.core.io.Resource;
+import org.springframework.web.client.HttpClientErrorException;
+
+/**
+ * Provides access to the binary files served by a Spring Cloud Config Server.
+ *
+ * @author Craig Walls
+ * @author Anshul Mehra
+ * @author Sharang Gupta
+ * @since 5.1.0
+ * @see ConfigResourceClient
+ */
+public interface BinaryResourceConfigClient {
+
+	/**
+	 * Retrieves a binary file using the configured profile and label.
+	 * @param path the path of the file, relative to the application's folder
+	 * @return the file served by the config server
+	 * @throws IllegalArgumentException when the application name or the config server URI
+	 * is undefined
+	 * @throws HttpClientErrorException when the file is not found
+	 */
+	Resource getBinaryResource(String path);
+
+	/**
+	 * Retrieves a binary file.
+	 * @param profile the profile, or {@code null} for the configured one; may be a
+	 * comma-separated list
+	 * @param label the label, or {@code null} for the configured one
+	 * @param path the path of the file, relative to the application's folder
+	 * @return the file served by the config server
+	 * @throws IllegalArgumentException when the application name or the config server URI
+	 * is undefined
+	 * @throws HttpClientErrorException when the file is not found
+	 */
+	Resource getBinaryResource(String profile, String label, String path);
+
+}

spring-cloud-config-client/src/main/java/org/springframework/cloud/config/client/ConfigClientProperties.java

@@ -31,8 +31,10 @@
 import org.springframework.cloud.config.environment.EnvironmentMediaType;
 import org.springframework.cloud.configuration.TlsProperties;
 import org.springframework.core.env.Environment;
+import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
+import org.springframework.util.unit.DataSize;
 import org.springframework.web.util.UriComponentsBuilder;
 
 /**
@@ -143,6 +145,12 @@ public class ConfigClientProperties {
 	 */
 	private Discovery discovery = new Discovery();
 
+	/**
+	 * Settings of the {@link ConfigResourceClient} that reads plain text and binary files
+	 * from the config server.
+	 */
+	private ResourceClient resourceClient = new ResourceClient();
+
 	/**
 	 * TLS properties.
 	 */
@@ -284,6 +292,14 @@ public Discovery getDiscovery() {
 		return this.discovery;
 	}
 
+	public ResourceClient getResourceClient() {
+		return this.resourceClient;
+	}
+
+	public void setResourceClient(ResourceClient resourceClient) {
+		this.resourceClient = resourceClient;
+	}
+
 	public void setDiscovery(Discovery discovery) {
 		this.discovery = discovery;
 	}
@@ -469,6 +485,28 @@ public String getUri() {
 
 	}
 
+	/**
+	 * Settings of the {@link ConfigResourceClient}.
+	 */
+	public static class ResourceClient {
+
+		/**
+		 * Maximum size of a file read from the config server; a larger file is rejected
+		 * instead of being loaded into memory. Zero disables the limit.
+		 */
+		private DataSize maxSize = DataSize.ofMegabytes(1);
+
+		public DataSize getMaxSize() {
+			return this.maxSize;
+		}
+
+		public void setMaxSize(DataSize maxSize) {
+			Assert.isTrue(!maxSize.isNegative(), "maxSize must not be negative");
+			this.maxSize = maxSize;
+		}
+
+	}
+
 	/**
 	 * Discovery properties.
 	 */

spring-cloud-config-client/src/main/java/org/springframework/cloud/config/client/ConfigResourceClient.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2013-present 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.client;
+
+/**
+ * Provides access to the plain text and binary files served by a Spring Cloud Config
+ * Server. When the configuration is imported with {@code spring.config.import}, a
+ * {@link ConfigResourceClient} that uses the same connection settings as the import is
+ * available as a bean.
+ *
+ * @author Daniel Lavoie
+ * @author Sharang Gupta
+ * @since 5.1.0
+ * @see ConfigResourceClientAutoConfiguration
+ */
+public interface ConfigResourceClient extends PlainTextConfigClient, BinaryResourceConfigClient {
+
+}

spring-cloud-config-client/src/main/java/org/springframework/cloud/config/client/ConfigResourceClientAutoConfiguration.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2013-present 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.client;
+
+import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.boot.autoconfigure.AutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.context.annotation.Bean;
+
+/**
+ * Auto-configuration for a {@link ConfigResourceClient} that reads plain text and binary
+ * files from the config server with the connection that loaded the configuration, when it
+ * was imported with {@code spring.config.import}.
+ *
+ * @author Daniel Lavoie
+ * @author Roy Clarkson
+ * @author Dylan Roberts
+ * @author Sharang Gupta
+ * @since 5.1.0
+ */
+@AutoConfiguration(after = ConfigClientAutoConfiguration.class)
+@ConditionalOnProperty(name = ConfigClientProperties.PREFIX + ".enabled", matchIfMissing = true)
+public class ConfigResourceClientAutoConfiguration {
+
+	@Bean
+	@ConditionalOnMissingBean(ConfigResourceClient.class)
+	@ConditionalOnBean(ConfigServerRestClientHolder.class)
+	public ConfigResourceClient configResourceClient(ConfigServerRestClientHolder restClientHolder,
+			@Qualifier(ConfigServerConfigDataLocationResolver.PROPERTIES_BEAN_NAME) ObjectProvider<ConfigClientProperties> importedProperties,
+			ObjectProvider<ConfigClientProperties> properties) {
+		// The properties resolved by the config server import describe the server the
+		// RestClient talks to; a context may also hold the ones bound by
+		// ConfigClientAutoConfiguration.
+		return new DefaultConfigResourceClient(restClientHolder.getRestClient(),
+				importedProperties.getIfAvailable(properties::getObject));
+	}
+
+}

spring-cloud-config-client/src/main/java/org/springframework/cloud/config/client/ConfigServerConfigDataLocationResolver.java

@@ -23,6 +23,8 @@
 
 import org.apache.commons.logging.Log;
 
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.boot.bootstrap.BootstrapContextClosedEvent;
 import org.springframework.boot.bootstrap.BootstrapRegistry;
 import org.springframework.boot.bootstrap.BootstrapRegistry.InstanceSupplier;
 import org.springframework.boot.bootstrap.ConfigurableBootstrapContext;
@@ -51,6 +53,7 @@
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
+import org.springframework.web.client.RestClient;
 import org.springframework.web.client.RestTemplate;
 
 import static org.springframework.cloud.config.client.ConfigClientProperties.CONFIG_DISCOVERY_ENABLED;
@@ -62,6 +65,13 @@
 	 * Prefix for Config Server imports.
 	 */
 	public static final String PREFIX = "configserver:";
+
+	/**
+	 * Name of the {@link ConfigClientProperties} bean resolved by the config server
+	 * import.
+	 */
+	public static final String PROPERTIES_BEAN_NAME = "configDataConfigClientProperties";
+
 	static final boolean RSA_IS_PRESENT = ClassUtils
 		.isPresent("org.springframework.security.crypto.encrypt.RsaSecretEncryptor", null);
 
@@ -241,8 +251,7 @@
 				InstanceSupplier.of(properties).withScope(BootstrapRegistry.Scope.PROTOTYPE));
 		bootstrapContext.addCloseListener(event -> event.getApplicationContext()
 			.getBeanFactory()
-			.registerSingleton("configDataConfigClientProperties",
-					event.getBootstrapContext().get(ConfigClientProperties.class)));
+			.registerSingleton(PROPERTIES_BEAN_NAME, event.getBootstrapContext().get(ConfigClientProperties.class)));
 
 		bootstrapContext.registerIfAbsent(ConfigClientRequestTemplateFactory.class, context -> {
 			ConfigClientRequestTemplateFactory factory = new ConfigClientRequestTemplateFactory(log,
@@ -252,10 +261,11 @@
 			return factory;
 		});
 
 		bootstrapContext.registerIfAbsent(RestTemplate.class, context -> {
 			ConfigClientRequestTemplateFactory factory = context.get(ConfigClientRequestTemplateFactory.class);
 			return factory.create();
 		});
+		bootstrapContext.addCloseListener(this::registerRestClientHolder);
 
 		bootstrapContext.registerIfAbsent(PropertyResolver.class,
 				context -> new PropertyResolver(resolverContext.getBinder(), getBindHandler(resolverContext)));
@@ -320,10 +330,36 @@
 
 		List<ConfigServerConfigDataResource> locations = new ArrayList<>();
 		locations.add(resource);
-
 		return locations;
 	}
 
+	/**
+	 * Keep the {@link RestTemplate} that loaded the configuration, which carries the URI,
+	 * credentials, headers, TLS settings, timeouts and interceptors of the client,
+	 * available as a {@link RestClient} to the {@link ConfigResourceClient}, without
+	 * exposing it as a {@link RestClient} bean.
+	 */
+	private void registerRestClientHolder(BootstrapContextClosedEvent event) {
+		ConfigurableListableBeanFactory beanFactory = event.getApplicationContext().getBeanFactory();
+		// The listener is added on every resolution (one per import location and
+		// profile pass) and runs that many times when the bootstrap context closes,
+		// while a singleton can only be registered once.
+		if (beanFactory.containsBean(ConfigServerRestClientHolder.BEAN_NAME)
+				|| !event.getBootstrapContext().isRegistered(RestTemplate.class)) {
+			return;
+		}
+		try {
+			RestClient restClient = RestClient.create(event.getBootstrapContext().get(RestTemplate.class));
+			beanFactory.registerSingleton(ConfigServerRestClientHolder.BEAN_NAME,
+					new ConfigServerRestClientHolder(restClient));
+		}
+		catch (RuntimeException ex) {
+			// An optional component must not prevent the application from starting
+			this.log.warn("Could not build a RestClient from the config client RestTemplate; "
+					+ "the ConfigResourceClient will not be available", ex);
+		}
+	}
+
 	public static class PropertyResolver {
 
 		private final Binder binder;

spring-cloud-config-client/src/main/java/org/springframework/cloud/config/client/ConfigServerRestClientHolder.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2013-present 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.client;
+
+import org.springframework.util.Assert;
+import org.springframework.web.client.RestClient;
+
+/**
+ * Holds the {@link RestClient} built from the {@code RestTemplate} that loaded the
+ * configuration from the config server, which carries the client's headers, credentials,
+ * TLS settings, timeouts and interceptors. It is registered as a bean of its own type,
+ * not as a {@link RestClient}, so that it is neither ambiguous with the application's own
+ * {@link RestClient} nor injected into it by accident.
+ *
+ * @author Sharang Gupta
+ * @since 5.1.0
+ */
+final class ConfigServerRestClientHolder {
+
+	/**
+	 * Name of the bean registered when the configuration is imported from the config
+	 * server.
+	 */
+	static final String BEAN_NAME = "configServerRestClientHolder";
+
+	private final RestClient restClient;
+
+	ConfigServerRestClientHolder(RestClient restClient) {
+		Assert.notNull(restClient, "RestClient must not be null");
+		this.restClient = restClient;
+	}
+
+	RestClient getRestClient() {
+		return this.restClient;
+	}
+
+}