Use spring-retry for consul config and discovery.

fixes gh-81

docs/src/main/asciidoc/spring-cloud-consul.adoc

@@ -185,6 +185,21 @@ You could store a YAML document in any of the keys listed above.
 
 You can change the data key using `spring.cloud.consul.config.data-key`.
 
+[[spring-cloud-consul-retry]]
+== Consul Retry
+
+If you expect that the consul agent may occasionally be unavailable when
+your app starts, you can ask it to keep trying after a failure. You need to add
+`spring-retry` and `spring-boot-starter-aop` to your classpath. The default
+behaviour is to retry 6 times with an initial backoff interval of 1000ms and an
+exponential multiplier of 1.1 for subsequent backoffs. You can configure these
+properties (and others) using `spring.cloud.consul.retry.*` configuration properties.
+This works with both Spring Cloud Consul Config and Discovery registration.
+
+TIP: To take full control of the retry add a `@Bean` of type
+`RetryOperationsInterceptor` with id "consulRetryInterceptor". Spring
+Retry has a `RetryInterceptorBuilder` that makes it easy to create one.
+
 [[spring-cloud-consul-bus]]
 == Spring Cloud Bus with Consul
 

spring-cloud-consul-config/pom.xml

@@ -22,6 +22,11 @@
 			<artifactId>spring-boot-starter-web</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.retry</groupId>
+			<artifactId>spring-retry</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>com.ecwid.consul</groupId>
 			<artifactId>consul-api</artifactId>

spring-cloud-consul-config/src/main/java/org/springframework/cloud/consul/config/ConsulPropertySourceLocator.java

@@ -22,16 +22,19 @@ import java.util.Collections;
 import java.util.List;
 
 import org.springframework.cloud.bootstrap.config.PropertySourceLocator;
+import org.springframework.core.annotation.Order;
 import org.springframework.core.env.CompositePropertySource;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.Environment;
 import org.springframework.core.env.PropertySource;
+import org.springframework.retry.annotation.Retryable;
 
 import com.ecwid.consul.v1.ConsulClient;
 
 /**
  * @author Spencer Gibb
  */
+@Order(0)
 public class ConsulPropertySourceLocator implements PropertySourceLocator {
 
 	private ConsulClient consul;
@@ -44,6 +47,7 @@ public class ConsulPropertySourceLocator implements PropertySourceLocator {
 	}
 
 	@Override
+	@Retryable(interceptor = "consulRetryInterceptor")
 	public PropertySource<?> locate(Environment environment) {
 		if (environment instanceof ConfigurableEnvironment) {
 			ConfigurableEnvironment env = (ConfigurableEnvironment) environment;

spring-cloud-consul-core/pom.xml

@@ -32,6 +32,16 @@
 			<artifactId>spring-cloud-commons</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.retry</groupId>
+			<artifactId>spring-retry</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>com.ecwid.consul</groupId>
 			<artifactId>consul-api</artifactId>

spring-cloud-consul-core/src/main/java/org/springframework/cloud/consul/ConsulAutoConfiguration.java

@@ -18,14 +18,21 @@ package org.springframework.cloud.consul;
 
 import com.ecwid.consul.v1.ConsulClient;
 
+import org.aspectj.lang.annotation.Aspect;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.actuate.endpoint.Endpoint;
+import org.springframework.boot.autoconfigure.aop.AopAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 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.retry.annotation.EnableRetry;
+import org.springframework.retry.annotation.Retryable;
+import org.springframework.retry.interceptor.RetryInterceptorBuilder;
+import org.springframework.retry.interceptor.RetryOperationsInterceptor;
 
 /**
  * @author Spencer Gibb
@@ -67,4 +74,23 @@ public class ConsulAutoConfiguration {
 			return new ConsulHealthIndicator(consulClient);
 		}
 	}
+
+	@ConditionalOnClass({ Retryable.class, Aspect.class, AopAutoConfiguration.class })
+	@Configuration
+	@EnableRetry(proxyTargetClass = true)
+	@Import(AopAutoConfiguration.class)
+	@EnableConfigurationProperties(RetryProperties.class)
+	protected static class RetryConfiguration {
+
+		@Bean(name = "consulRetryInterceptor")
+		@ConditionalOnMissingBean(name = "consulRetryInterceptor")
+		public RetryOperationsInterceptor consulRetryInterceptor(
+				RetryProperties properties) {
+			return RetryInterceptorBuilder
+					.stateless()
+					.backOffOptions(properties.getInitialInterval(),
+							properties.getMultiplier(), properties.getMaxInterval())
+					.maxAttempts(properties.getMaxAttempts()).build();
+		}
+	}
 }

spring-cloud-consul-core/src/main/java/org/springframework/cloud/consul/ConsulProperties.java

@@ -28,12 +28,15 @@ import org.springframework.boot.context.properties.ConfigurationProperties;
 @ConfigurationProperties("spring.cloud.consul")
 @Data
 public class ConsulProperties {
+	/** Consul agent hostname. Defaults to 'localhost'. */
 	@NotNull
 	private String host = "localhost";
 
+	/** Consul agent port. Defaults to '8500'. */
 	@NotNull
 	private int port = 8500;
 
+	/** Is spring cloud consul enabled */
 	private boolean enabled = true;
 
 	private String prefix = "config";

spring-cloud-consul-core/src/main/java/org/springframework/cloud/consul/RetryProperties.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2013-2016 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.consul;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+import lombok.Data;
+
+/**
+ * @author Spencer Gibb
+ */
+@ConfigurationProperties("spring.cloud.consul.retry")
+@Data
+public class RetryProperties {
+
+	/** Initial retry interval in milliseconds. */
+	private long initialInterval = 1000;
+
+	/** Multiplier for next interval. */
+	private double multiplier = 1.1;
+
+	/** Maximum interval for backoff. */
+	private long maxInterval = 2000;
+
+	/** Maximum number of attempts. */
+	private int maxAttempts = 6;
+}

spring-cloud-consul-dependencies/pom.xml

@@ -125,6 +125,11 @@
 				<artifactId>joda-time</artifactId>
 				<version>${joda-time.version}</version>
 			</dependency>
+			<dependency>
+				<groupId>org.springframework.retry</groupId>
+				<artifactId>spring-retry</artifactId>
+				<version>1.1.2.RELEASE</version>
+			</dependency>
 			<dependency>
 				<groupId>org.springframework.cloud</groupId>
 				<artifactId>spring-cloud-netflix-dependencies</artifactId>

spring-cloud-consul-discovery/pom.xml

@@ -82,6 +82,11 @@
 			<artifactId>ribbon-loadbalancer</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.retry</groupId>
+			<artifactId>spring-retry</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>org.projectlombok</groupId>
 			<artifactId>lombok</artifactId>

spring-cloud-consul-discovery/src/main/java/org/springframework/cloud/consul/discovery/ConsulLifecycle.java

@@ -25,6 +25,7 @@ import lombok.extern.slf4j.Slf4j;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.cloud.client.discovery.AbstractDiscoveryLifecycle;
+import org.springframework.retry.annotation.Retryable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -69,6 +70,12 @@ public class ConsulLifecycle extends AbstractDiscoveryLifecycle {
 		service.setPort(port);
 	}
 
+	@Override
+	@Retryable(interceptor = "consulRetryInterceptor")
+	public void start() {
+		super.start();
+	}
+
 	@Override
 	protected void register() {
 		Assert.notNull(service.getPort(), "service.port has not been set");