If failFast=false only log warnings for config loading.

fixes gh-137

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

@@ -185,6 +185,11 @@ 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-failfast]]
+== Fail Fast
+
+It may be convenient in certain circumstances (like local development or certain test scenarios) to not fail if consul isn't available for configuration. Setting `spring.cloud.consul.config.failFast=false` will cause the configuration module to log a warning rather than throw an exception. This will allow the application to continue startup normally.
+
 [[spring-cloud-consul-retry]]
 == Consul Retry
 
@@ -203,7 +208,7 @@ Retry has a `RetryInterceptorBuilder` that makes it easy to create one.
 [[spring-cloud-consul-bus]]
 == Spring Cloud Bus with Consul
 
-TODO: document Spring Cloud Consul Bus
+Coming in a later release.
 
 [[spring-cloud-consul-hystrix]]
 == Circuit Breaker with Hystrix

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

@@ -56,6 +56,11 @@ public class ConsulConfigProperties {
 
 	private Watch watch = new Watch();
 
+	/**
+	 * Throw exceptions during config lookup if true, otherwise, log warnings.
+	 */
+	private boolean failFast = true;
+
 	@Data
 	public class Watch {
 		private int waitTime = 2;

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

@@ -28,13 +28,17 @@ 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 org.springframework.util.ReflectionUtils;
 
 import com.ecwid.consul.v1.ConsulClient;
 
+import lombok.extern.apachecommons.CommonsLog;
+
 /**
  * @author Spencer Gibb
  */
 @Order(0)
+@CommonsLog
 public class ConsulPropertySourceLocator implements PropertySourceLocator {
 
 	private ConsulClient consul;
@@ -75,9 +79,17 @@ public class ConsulPropertySourceLocator implements PropertySourceLocator {
 			Collections.reverse(this.contexts);
 
 			for (String propertySourceContext : this.contexts) {
-				ConsulPropertySource propertySource = create(propertySourceContext);
-				propertySource.init();
-				composite.addPropertySource(propertySource);
+				try {
+					ConsulPropertySource propertySource = create(propertySourceContext);
+					propertySource.init();
+					composite.addPropertySource(propertySource);
+				} catch (Exception e) {
+					if (this.properties.isFailFast()) {
+						ReflectionUtils.rethrowRuntimeException(e);
+					} else {
+						log.warn("Unable to load consul config from "+ propertySourceContext, e);
+					}
+				}
 			}
 
 			return composite;

spring-cloud-consul-config/src/test/java/org/springframework/cloud/consul/config/ConsulPropertySourceLocatorFailFastTests.java

@@ -0,0 +1,48 @@
+/*
+ * 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.config;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.SpringApplicationConfiguration;
+import org.springframework.boot.test.WebIntegrationTest;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+/**
+ * @author Spencer Gibb
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = ConsulPropertySourceLocatorFailFastTests.Config.class)
+@WebIntegrationTest(value = {"spring.application.name=testConsulPropertySourceLocatorFailFast",
+		"spring.cloud.consul.host=53210a7c-4809-42cb-8b30-057d2db85fcc",
+		"spring.cloud.consul.port=65530",
+		"spring.cloud.consul.retry.maxAttempts=0",
+		"spring.cloud.consul.config.failFast=false"}, randomPort = true)
+public class ConsulPropertySourceLocatorFailFastTests {
+
+	@Configuration
+	@EnableAutoConfiguration
+	static class Config {
+	}
+
+	@Test
+	public void testFailFastFalse() {
+	}
+
+}