Add support for retry in config client

If Spring Retry is on the classpath (and AspectJ) the config client
will create a proxy for the ConfigServerPropertySourceLocator that
retries a failed environment fetch. In this way the client can be
made to wait for the config server to come up, even if failFast=true.
(If failFast=false, the default, then it has no effect.)

Fixes gh-90, fixes gh-129

pom.xml

@@ -41,6 +41,11 @@
 			<artifactId>spring-cloud-config-server</artifactId>
 	        <version>1.0.1.BUILD-SNAPSHOT</version>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.retry</groupId>
+			<artifactId>spring-retry</artifactId>
+			<version>1.1.2.RELEASE</version>
+		</dependency>
 		<dependency>
 			<groupId>org.eclipse.jgit</groupId>
 			<artifactId>org.eclipse.jgit</artifactId>

spring-cloud-config-client/pom.xml

@@ -43,11 +43,21 @@
 			<groupId>org.springframework</groupId>
 			<artifactId>spring-web</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.retry</groupId>
+			<artifactId>spring-retry</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-actuator</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-aop</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>

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

@@ -62,5 +62,5 @@ public class ConfigClientAutoConfiguration {
 			return new ConfigServerHealthIndicator(locator);
 		}
 	}
-
+	
 }

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

@@ -16,12 +16,21 @@
 
 package org.springframework.cloud.config.client;
 
+import org.aspectj.lang.annotation.Aspect;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.aop.AopAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
 import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.retry.annotation.EnableRetry;
+import org.springframework.retry.annotation.Retryable;
+import org.springframework.retry.interceptor.RetryInterceptorBuilder;
+import org.springframework.retry.interceptor.RetryOperationsInterceptor;
 
 /**
  * @author Dave Syer
@@ -48,4 +57,23 @@ public class ConfigServiceBootstrapConfiguration {
 		return locator;
 	}
 
+	@ConditionalOnClass({ Retryable.class, Aspect.class, AopAutoConfiguration.class })
+	@Configuration
+	@EnableRetry(proxyTargetClass = true)
+	@Import(AopAutoConfiguration.class)
+	@EnableConfigurationProperties(RetryProperties.class)
+	protected static class RetryConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean(name = "configServerRetryInterceptor")
+		public RetryOperationsInterceptor configServerRetryInterceptor(
+				RetryProperties properties) {
+			return RetryInterceptorBuilder
+					.stateless()
+					.backOffOptions(properties.getInitialInterval(),
+							properties.getMultiplier(), properties.getMaxInterval())
+					.maxAttempts(properties.getMaxAttempts()).build();
+		}
+	}
+
 }

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

@@ -35,6 +35,7 @@ import org.springframework.http.MediaType;
 import org.springframework.http.client.ClientHttpRequestExecution;
 import org.springframework.http.client.ClientHttpRequestInterceptor;
 import org.springframework.http.client.ClientHttpResponse;
+import org.springframework.retry.annotation.Retryable;
 import org.springframework.util.StringUtils;
 import org.springframework.web.client.HttpServerErrorException;
 import org.springframework.web.client.RestTemplate;
@@ -57,6 +58,7 @@ public class ConfigServicePropertySourceLocator implements PropertySourceLocator
 	}
 
 	@Override
+	@Retryable(interceptor="configServerRetryInterceptor")
 	public org.springframework.core.env.PropertySource<?> locate(
 			org.springframework.core.env.Environment environment) {
 		ConfigClientProperties client = defaults.override(environment);

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

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2014-2015 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
+ *
+ *      http://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.boot.context.properties.ConfigurationProperties;
+
+/**
+ * @author Dave Syer
+ *
+ */
+@ConfigurationProperties("spring.config.retry")
+public class RetryProperties {
+
+	/**
+	 * Initial retry interval in milliseconds.
+	 */
+	long initialInterval = 1000;
+	/**
+	 * Multiplier for next interval.
+	 */
+	double multiplier = 1.1;
+	/**
+	 * Maximum interval for backoff.
+	 */
+	long maxInterval = 2000;
+	/**
+	 * Maximum number of attempts.
+	 */
+	int maxAttempts = 6;
+
+	public long getInitialInterval() {
+		return this.initialInterval;
+	}
+
+	public void setInitialInterval(long initialInterval) {
+		this.initialInterval = initialInterval;
+	}
+
+	public double getMultiplier() {
+		return this.multiplier;
+	}
+
+	public void setMultiplier(double multiplier) {
+		this.multiplier = multiplier;
+	}
+
+	public long getMaxInterval() {
+		return this.maxInterval;
+	}
+
+	public void setMaxInterval(long maxInterval) {
+		this.maxInterval = maxInterval;
+	}
+
+	public int getMaxAttempts() {
+		return this.maxAttempts;
+	}
+
+	public void setMaxAttempts(int maxAttempts) {
+		this.maxAttempts = maxAttempts;
+	}
+
+}