Allow loading of config maps to be retried on failure

spring-cloud-kubernetes-config/pom.xml

@@ -67,6 +67,12 @@
 			<artifactId>spring-security-rsa</artifactId>
 		</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-kubernetes-config/src/main/java/org/springframework/cloud/kubernetes/config/BootstrapConfiguration.java

@@ -16,18 +16,22 @@
 
 package org.springframework.cloud.kubernetes.config;
 
+import java.util.Optional;
+
 import io.fabric8.kubernetes.api.model.ConfigMap;
 import io.fabric8.kubernetes.api.model.Secret;
 import io.fabric8.kubernetes.client.KubernetesClient;
 
 import org.springframework.beans.factory.annotation.Autowired;
 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.cloud.kubernetes.KubernetesAutoConfiguration;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
+import org.springframework.retry.support.RetryTemplate;
 
 /**
  * Auto configuration that reuses Kubernetes config maps as property sources.
@@ -49,8 +53,10 @@ protected static class KubernetesPropertySourceConfiguration {
 
 		@Bean
 		@ConditionalOnProperty(name = "spring.cloud.kubernetes.config.enabled", matchIfMissing = true)
-		public ConfigMapPropertySourceLocator configMapPropertySourceLocator(ConfigMapConfigProperties properties) {
-			return new ConfigMapPropertySourceLocator(this.client, properties);
+		public ConfigMapPropertySourceLocator configMapPropertySourceLocator(ConfigMapConfigProperties properties,
+				Optional<ConfigMapRetryTemplateFactory> configMapRetryTemplateFactory) {
+			return new ConfigMapPropertySourceLocator(this.client, properties,
+					configMapRetryTemplateFactory.orElse(null));
 		}
 
 		@Bean
@@ -59,6 +65,15 @@ public SecretsPropertySourceLocator secretsPropertySourceLocator(SecretsConfigPr
 			return new SecretsPropertySourceLocator(this.client, properties);
 		}
 
+		@Bean
+		@ConditionalOnMissingBean
+		@ConditionalOnClass(RetryTemplate.class)
+		public ConfigMapRetryTemplateFactory configMapRetryPolicyFactory(ConfigMapConfigProperties properties) {
+			final RetryTemplate template = RetryTemplate.builder().maxAttempts(properties.getRetry().getMaxAttempts())
+					.fixedBackoff(properties.getRetry().getBackoff().toMillis()).retryOn(Exception.class).build();
+			return () -> template;
+		}
+
 	}
 
 }

spring-cloud-kubernetes-config/src/main/java/org/springframework/cloud/kubernetes/config/ConfigMapConfigProperties.java

@@ -16,6 +16,7 @@
 
 package org.springframework.cloud.kubernetes.config;
 
+import java.time.Duration;
 import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -27,6 +28,7 @@
  * Config map configuration properties.
  *
  * @author Ioannis Canellos
+ * @author Roy Jacobs
  */
 @ConfigurationProperties("spring.cloud.kubernetes.config")
 public class ConfigMapConfigProperties extends AbstractConfigProperties {
@@ -39,6 +41,8 @@ public class ConfigMapConfigProperties extends AbstractConfigProperties {
 
 	private List<Source> sources = Collections.emptyList();
 
+	private Retry retry = new Retry();
+
 	public boolean isEnableApi() {
 		return this.enableApi;
 	}
@@ -63,6 +67,14 @@ public void setSources(List<Source> sources) {
 		this.sources = sources;
 	}
 
+	public Retry getRetry() {
+		return retry;
+	}
+
+	public void setRetry(Retry retry) {
+		this.retry = retry;
+	}
+
 	/**
 	 * @return A list of Source to use If the user has not specified any Source
 	 * properties, then a single Source is constructed based on the supplied name and
@@ -73,9 +85,8 @@ public void setSources(List<Source> sources) {
 	 */
 	public List<NormalizedSource> determineSources() {
 		if (this.sources.isEmpty()) {
-			return Collections.singletonList(
-					new NormalizedSource(ConfigMapConfigProperties.this.name,
-							ConfigMapConfigProperties.this.namespace));
+			return Collections.singletonList(new NormalizedSource(ConfigMapConfigProperties.this.name,
+					ConfigMapConfigProperties.this.namespace));
 		}
 
 		return this.sources.stream().map(s -> s.normalize(this.name, this.namespace)).collect(Collectors.toList());
@@ -138,6 +149,39 @@ public NormalizedSource normalize(String defaultName, String defaultNamespace) {
 
 	}
 
+	public static class Retry {
+
+		/**
+		 * The amount of times to try contacting Kubernetes to load config maps.
+		 */
+		private int maxAttempts = 3;
+
+		/**
+		 * The delay in between attempts to load config maps.
+		 */
+		private Duration backoff = Duration.ofSeconds(1);
+
+		public Retry() {
+		}
+
+		public int getMaxAttempts() {
+			return maxAttempts;
+		}
+
+		public void setMaxAttempts(int maxAttempts) {
+			this.maxAttempts = maxAttempts;
+		}
+
+		public Duration getBackoff() {
+			return backoff;
+		}
+
+		public void setBackoff(Duration backoff) {
+			this.backoff = backoff;
+		}
+
+	}
+
 	static class NormalizedSource {
 
 		private final String name;

spring-cloud-kubernetes-config/src/main/java/org/springframework/cloud/kubernetes/config/ConfigMapPropertySource.java

@@ -30,6 +30,7 @@
 import org.springframework.core.env.Environment;
 import org.springframework.core.env.MapPropertySource;
 import org.springframework.core.env.StandardEnvironment;
+import org.springframework.retry.support.RetryTemplate;
 import org.springframework.util.StringUtils;
 
 import static org.springframework.cloud.kubernetes.config.PropertySourceUtils.KEY_VALUE_TO_PROPERTIES;
@@ -43,6 +44,7 @@
  * @author Ioannis Canellos
  * @author Ali Shahbour
  * @author Michael Moudatsos
+ * @author Roy Jacobs
  */
 public class ConfigMapPropertySource extends MapPropertySource {
 
@@ -71,7 +73,13 @@ private static Environment createEnvironmentWithActiveProfiles(String[] activePr
 	}
 
 	public ConfigMapPropertySource(KubernetesClient client, String name, String namespace, Environment environment) {
-		super(getName(client, name, namespace), asObjectMap(getData(client, name, namespace, environment)));
+		this(client, name, namespace, environment, null);
+	}
+
+	public ConfigMapPropertySource(KubernetesClient client, String name, String namespace, Environment environment,
+			ConfigMapRetryTemplateFactory configMapRetryTemplateFactory) {
+		super(getName(client, name, namespace),
+				asObjectMap(getData(client, name, namespace, environment, configMapRetryTemplateFactory)));
 	}
 
 	private static String getName(KubernetesClient client, String name, String namespace) {
@@ -81,40 +89,59 @@ private static String getName(KubernetesClient client, String name, String names
 	}
 
 	private static Map<String, Object> getData(KubernetesClient client, String name, String namespace,
-			Environment environment) {
+			Environment environment, ConfigMapRetryTemplateFactory configMapRetryTemplateFactory) {
 		try {
-			Map<String, Object> result = new LinkedHashMap<>();
-			ConfigMap map = StringUtils.isEmpty(namespace) ? client.configMaps().withName(name).get()
-					: client.configMaps().inNamespace(namespace).withName(name).get();
-
-			if (map != null) {
-				result.putAll(processAllEntries(map.getData(), environment));
+			if (configMapRetryTemplateFactory == null) {
+				return tryGetData(client, name, namespace, environment);
 			}
+			else {
+				final RetryTemplate retryTemplate = configMapRetryTemplateFactory.getRetryTemplate();
+				return retryTemplate.execute(ctx -> {
+					try {
+						return tryGetData(client, name, namespace, environment);
+					}
+					catch (Exception e) {
+						LOG.warn("Can't read configMap with name: [" + name + "] in namespace:[" + namespace
+								+ "]. Retrying.", e);
+						throw e;
+					}
+				});
+			}
+		}
+		catch (Exception e) {
+			LOG.warn("Can't read configMap with name: [" + name + "] in namespace:[" + namespace + "]. Ignoring.", e);
+		}
+
+		return new LinkedHashMap<>();
+	}
 
-			if (environment != null) {
-				for (String activeProfile : environment.getActiveProfiles()) {
+	private static Map<String, Object> tryGetData(KubernetesClient client, String name, String namespace,
+			Environment environment) {
+		Map<String, Object> result = new LinkedHashMap<>();
+		ConfigMap map = StringUtils.isEmpty(namespace) ? client.configMaps().withName(name).get()
+				: client.configMaps().inNamespace(namespace).withName(name).get();
 
-					String mapNameWithProfile = name + "-" + activeProfile;
+		if (map != null) {
+			result.putAll(processAllEntries(map.getData(), environment));
+		}
 
-					ConfigMap mapWithProfile = StringUtils.isEmpty(namespace)
-							? client.configMaps().withName(mapNameWithProfile).get()
-							: client.configMaps().inNamespace(namespace).withName(mapNameWithProfile).get();
+		if (environment != null) {
+			for (String activeProfile : environment.getActiveProfiles()) {
 
-					if (mapWithProfile != null) {
-						result.putAll(processAllEntries(mapWithProfile.getData(), environment));
-					}
+				String mapNameWithProfile = name + "-" + activeProfile;
 
-				}
-			}
+				ConfigMap mapWithProfile = StringUtils.isEmpty(namespace)
+						? client.configMaps().withName(mapNameWithProfile).get()
+						: client.configMaps().inNamespace(namespace).withName(mapNameWithProfile).get();
 
-			return result;
+				if (mapWithProfile != null) {
+					result.putAll(processAllEntries(mapWithProfile.getData(), environment));
+				}
 
-		}
-		catch (Exception e) {
-			LOG.warn("Can't read configMap with name: [" + name + "] in namespace:[" + namespace + "]. Ignoring.", e);
+			}
 		}
 
-		return new LinkedHashMap<>();
+		return result;
 	}
 
 	private static Map<String, Object> processAllEntries(Map<String, String> input, Environment environment) {

spring-cloud-kubernetes-config/src/main/java/org/springframework/cloud/kubernetes/config/ConfigMapPropertySourceLocator.java

@@ -48,6 +48,7 @@
  *
  * @author Ioannis Canellos
  * @author Michael Moudatsos
+ * @author Roy Jacobs
  */
 @Order(0)
 public class ConfigMapPropertySourceLocator implements PropertySourceLocator {
@@ -58,9 +59,17 @@ public class ConfigMapPropertySourceLocator implements PropertySourceLocator {
 
 	private final ConfigMapConfigProperties properties;
 
+	private final ConfigMapRetryTemplateFactory configMapRetryTemplateFactory;
+
 	public ConfigMapPropertySourceLocator(KubernetesClient client, ConfigMapConfigProperties properties) {
+		this(client, properties, null);
+	}
+
+	public ConfigMapPropertySourceLocator(KubernetesClient client, ConfigMapConfigProperties properties,
+			ConfigMapRetryTemplateFactory configMapRetryTemplateFactory) {
 		this.client = client;
 		this.properties = properties;
+		this.configMapRetryTemplateFactory = configMapRetryTemplateFactory;
 	}
 
 	@Override
@@ -87,8 +96,8 @@ private MapPropertySource getMapPropertySourceForSingleConfigMap(ConfigurableEnv
 		String configurationTarget = this.properties.getConfigurationTarget();
 		return new ConfigMapPropertySource(this.client,
 				getApplicationName(environment, normalizedSource.getName(), configurationTarget),
-				getApplicationNamespace(this.client, normalizedSource.getNamespace(), configurationTarget),
-				environment);
+				getApplicationNamespace(this.client, normalizedSource.getNamespace(), configurationTarget), environment,
+				configMapRetryTemplateFactory);
 	}
 
 	private void addPropertySourcesFromPaths(Environment environment, CompositePropertySource composite) {

spring-cloud-kubernetes-config/src/main/java/org/springframework/cloud/kubernetes/config/ConfigMapRetryTemplateFactory.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2013-2020 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.kubernetes.config;
+
+import org.springframework.retry.support.RetryTemplate;
+
+/**
+ * This interface determines which retry logic to apply if there are any errors during the
+ * loading of config maps at application startup.
+ *
+ * @author Roy Jacobs
+ */
+public interface ConfigMapRetryTemplateFactory {
+
+	/**
+	 * @return the {@link RetryTemplate} to use when loading config maps.
+	 */
+	RetryTemplate getRetryTemplate();
+
+}

spring-cloud-kubernetes-config/src/main/java/org/springframework/cloud/kubernetes/config/ConfigUtils.java

@@ -39,26 +39,21 @@ private ConfigUtils() {
 		throw new IllegalStateException("Can't instantiate a utility class");
 	}
 
-	public static String getApplicationName(Environment env, String configName,
-			String configurationTarget) {
+	public static String getApplicationName(Environment env, String configName, String configurationTarget) {
 		if (StringUtils.isEmpty(configName)) {
 			// TODO: use relaxed binding
-			LOG.debug(configurationTarget
-					+ " name has not been set, taking it from property/env "
-					+ SPRING_APPLICATION_NAME + " (default=" + FALLBACK_APPLICATION_NAME
-					+ ")");
-			configName = env.getProperty(SPRING_APPLICATION_NAME,
-					FALLBACK_APPLICATION_NAME);
+			LOG.debug(configurationTarget + " name has not been set, taking it from property/env "
+					+ SPRING_APPLICATION_NAME + " (default=" + FALLBACK_APPLICATION_NAME + ")");
+			configName = env.getProperty(SPRING_APPLICATION_NAME, FALLBACK_APPLICATION_NAME);
 		}
 
 		return configName;
 	}
 
-	public static String getApplicationNamespace(KubernetesClient client,
-			String configNamespace, String configurationTarget) {
+	public static String getApplicationNamespace(KubernetesClient client, String configNamespace,
+			String configurationTarget) {
 		if (StringUtils.isEmpty(configNamespace)) {
-			LOG.debug(configurationTarget
-					+ " namespace has not been set, taking it from client (ns="
+			LOG.debug(configurationTarget + " namespace has not been set, taking it from client (ns="
 					+ client.getNamespace() + ")");
 			configNamespace = client.getNamespace();
 		}