CAMEL-20371: Asynchrnous Camel health checks

core/camel-spring-boot/src/main/docs/spring-boot.adoc

@@ -417,6 +417,24 @@ or by providing GraalVM JSON hint files that can be generated by the https://doc
 
 For more details about `GraalVM Native Image Support` in Spring Boot please refer to https://docs.spring.io/spring-boot/docs/current/reference/html/native-image.html
 
+== Camel Asynchronous Health Checks
+
+Camel health checks can be executed asynchronously via a Task Scheduler so that the result can be cached and the actual health check is executed in background every few seconds. Asynchronous Camel health checks are disabled by default but can be enabled with the following property:
+
+[source,properties]
+----
+camel.health.async-camel-health-check=true
+----
+
+moreover the Camel health check task scheduler can be customized with the following properties:
+
+[source,properties]
+----
+camel.health.healthCheckPoolSize=5
+camel.health.healthCheckFrequency=10
+camel.health.healthCheckThreadNamePrefix=CamelHealthTaskScheduler
+----
+
 == Camel Readiness and Liveness State Indicators
 
 Camel specific Readiness and Liveness checks can be added to a Spring Boot 3 application including respectively in the

core/camel-spring-boot/src/main/docs/spring-boot.json

@@ -513,6 +513,13 @@
       "sourceType": "org.apache.camel.spring.boot.debug.CamelDebugConfigurationProperties",
       "defaultValue": false
     },
+    {
+      "name": "camel.health.async-camel-health-check",
+      "type": "java.lang.Boolean",
+      "description": "Whether Camel Health Checks are executed asynchronously <p> disabled by default",
+      "sourceType": "org.apache.camel.spring.boot.actuate.health.CamelHealthCheckConfigurationProperties",
+      "defaultValue": false
+    },
     {
       "name": "camel.health.consumers-enabled",
       "type": "java.lang.Boolean",
@@ -538,6 +545,27 @@
       "sourceType": "org.apache.camel.spring.boot.actuate.health.CamelHealthCheckConfigurationProperties",
       "defaultValue": "default"
     },
+    {
+      "name": "camel.health.health-check-frequency",
+      "type": "java.lang.Integer",
+      "description": "Camel's HealthCheck frequency in seconds",
+      "sourceType": "org.apache.camel.spring.boot.actuate.health.CamelHealthCheckConfigurationProperties",
+      "defaultValue": 10
+    },
+    {
+      "name": "camel.health.health-check-pool-size",
+      "type": "java.lang.Integer",
+      "description": "Camel HealthCheck pool size",
+      "sourceType": "org.apache.camel.spring.boot.actuate.health.CamelHealthCheckConfigurationProperties",
+      "defaultValue": 5
+    },
+    {
+      "name": "camel.health.health-check-thread-name-prefix",
+      "type": "java.lang.String",
+      "description": "Camel HealthCheck thread name prefix",
+      "sourceType": "org.apache.camel.spring.boot.actuate.health.CamelHealthCheckConfigurationProperties",
+      "defaultValue": "CamelHealthTaskScheduler"
+    },
     {
       "name": "camel.health.initial-state",
       "type": "java.lang.String",

core/camel-spring-boot/src/main/java/org/apache/camel/spring/boot/actuate/health/AsyncHealthIndicatorAutoConfiguration.java

@@ -0,0 +1,126 @@
+package org.apache.camel.spring.boot.actuate.health;
+
+import org.apache.camel.spring.boot.actuate.health.liveness.CamelLivenessStateHealthIndicator;
+import org.apache.camel.spring.boot.actuate.health.readiness.CamelReadinessStateHealthIndicator;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.boot.actuate.health.Health;
+import org.springframework.boot.actuate.health.HealthContributorRegistry;
+import org.springframework.boot.actuate.health.HealthIndicator;
+import org.springframework.boot.actuate.health.NamedContributor;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.scheduling.TaskScheduler;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
+
+import java.time.Duration;
+import java.time.ZonedDateTime;
+
+/**
+ * Configuration class that replace synchronous Camel Health Checks with asynchronous ones.
+ *
+ * This implementation is based on https://github.com/spring-projects/spring-boot/issues/2652 that most probably
+ * will be added in spring boot 3.2.x as a new feature in the future.
+ *
+ * TODO: To be refactored once async health contributors feature will be added in spring boot.
+ *
+ */
+@Configuration
+@ConditionalOnProperty(prefix = "camel.health", name = "async-camel-health-check", havingValue = "true")
+public class AsyncHealthIndicatorAutoConfiguration implements InitializingBean {
+	private static final Logger log = LoggerFactory.getLogger(AsyncHealthIndicatorAutoConfiguration.class);
+
+	private HealthContributorRegistry healthContributorRegistry;
+	private TaskScheduler taskScheduler;
+	private CamelHealthCheckConfigurationProperties config;
+
+	public AsyncHealthIndicatorAutoConfiguration(HealthContributorRegistry healthContributorRegistry,
+												 CamelHealthCheckConfigurationProperties config) {
+		this.healthContributorRegistry = healthContributorRegistry;
+		this.config = config;
+
+		ThreadPoolTaskScheduler threadPoolTaskScheduler = new ThreadPoolTaskScheduler();
+		threadPoolTaskScheduler.setPoolSize(config.getHealthCheckPoolSize());
+		threadPoolTaskScheduler.setThreadNamePrefix(config.getHealthCheckThreadNamePrefix());
+		threadPoolTaskScheduler.initialize();
+		taskScheduler = threadPoolTaskScheduler;
+	}
+
+	@Override
+	public void afterPropertiesSet() throws Exception {
+		for (NamedContributor<?> namedContributor : healthContributorRegistry) {
+			final String name = namedContributor.getName();
+			final Object contributor = namedContributor.getContributor();
+			if (contributor instanceof CamelHealthCheckIndicator
+				|| contributor instanceof CamelLivenessStateHealthIndicator
+				|| contributor instanceof CamelReadinessStateHealthIndicator) {
+				HealthIndicator camelHealthCheckIndicator = (HealthIndicator) contributor;
+				healthContributorRegistry.unregisterContributor(name);
+				log.debug(
+						"Wrapping " + contributor.getClass().getSimpleName() + " for async health scheduling");
+				WrappedHealthIndicator wrappedHealthIndicator =
+						new WrappedHealthIndicator(camelHealthCheckIndicator);
+				healthContributorRegistry.registerContributor(name, wrappedHealthIndicator);
+				taskScheduler.scheduleWithFixedDelay(
+						wrappedHealthIndicator, Duration.ofSeconds(config.getHealthCheckFrequency()));
+			}
+		}
+	}
+
+	/**
+	 * Health Check Indicator that executes Health Checks within a Task Scheduler
+	 */
+	private static class WrappedHealthIndicator implements HealthIndicator, Runnable {
+		private static final String LAST_CHECKED_KEY = "lastChecked";
+		private static final String LAST_DURATION_KEY = "lastDuration";
+
+		private HealthIndicator wrappedHealthIndicator;
+
+		private Health lastHealth;
+
+		public WrappedHealthIndicator(HealthIndicator wrappedHealthIndicator) {
+			this.wrappedHealthIndicator = wrappedHealthIndicator;
+		}
+
+		@Override
+		public Health health() {
+			Health lastHealth = getLastHealth();
+			if (lastHealth == null) {
+				setLastHealth(getAndWrapHealth());
+				lastHealth = getLastHealth();
+			}
+
+			return lastHealth;
+		}
+
+		private Health getAndWrapHealth() {
+			ZonedDateTime startTime = ZonedDateTime.now();
+			Health baseHealth = getWrappedHealthIndicator().health();
+			ZonedDateTime endTime = ZonedDateTime.now();
+			Duration duration = Duration.between(startTime, endTime);
+			return Health.status(baseHealth.getStatus())
+					.withDetails(baseHealth.getDetails())
+					.withDetail(LAST_CHECKED_KEY, startTime)
+					.withDetail(LAST_DURATION_KEY, duration)
+					.build();
+		}
+
+		@Override
+		public void run() {
+			setLastHealth(getAndWrapHealth());
+		}
+
+		public HealthIndicator getWrappedHealthIndicator() {
+			return wrappedHealthIndicator;
+		}
+
+		public Health getLastHealth() {
+			return lastHealth;
+		}
+
+		public void setLastHealth(Health lastHealth) {
+			this.lastHealth = lastHealth;
+		}
+	}
+}

core/camel-spring-boot/src/main/java/org/apache/camel/spring/boot/actuate/health/CamelHealthCheckConfigurationProperties.java

@@ -63,6 +63,28 @@ public class CamelHealthCheckConfigurationProperties {
      */
     private String excludePattern;
 
+    /**
+     * Camel's HealthCheck frequency in seconds
+     */
+    private int healthCheckFrequency = 10;
+
+    /**
+     * Camel HealthCheck pool size
+     */
+    private int healthCheckPoolSize = 5;
+
+    /**
+     * Camel HealthCheck thread name prefix
+     */
+    private String healthCheckThreadNamePrefix = "CamelHealthTaskScheduler";
+
+    /**
+     * Whether Camel Health Checks are executed asynchronously
+     * <p>
+     * disabled by default
+     */
+    private boolean asyncCamelHealthCheck = false;
+
     /**
      * Sets the level of details to exposure as result of invoking health checks. There are the following levels: full,
      * default, oneline
@@ -158,6 +180,38 @@ public String getInitialState() {
     public void setInitialState(String initialState) {
         this.initialState = initialState;
     }
+
+    public int getHealthCheckFrequency() {
+        return healthCheckFrequency;
+    }
+
+    public void setHealthCheckFrequency(int healthCheckFrequency) {
+        this.healthCheckFrequency = healthCheckFrequency;
+    }
+
+    public int getHealthCheckPoolSize() {
+        return healthCheckPoolSize;
+    }
+
+    public void setHealthCheckPoolSize(int healthCheckPoolSize) {
+        this.healthCheckPoolSize = healthCheckPoolSize;
+    }
+
+    public String getHealthCheckThreadNamePrefix() {
+        return healthCheckThreadNamePrefix;
+    }
+
+    public void setHealthCheckThreadNamePrefix(String healthCheckThreadNamePrefix) {
+        this.healthCheckThreadNamePrefix = healthCheckThreadNamePrefix;
+    }
+
+    public boolean isAsyncCamelHealthCheck() {
+        return asyncCamelHealthCheck;
+    }
+
+    public void setAsyncCamelHealthCheck(boolean asyncCamelHealthCheck) {
+        this.asyncCamelHealthCheck = asyncCamelHealthCheck;
+    }
 }
 
 

core/camel-spring-boot/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -19,6 +19,7 @@ org.apache.camel.spring.boot.CamelAutoConfiguration
 org.apache.camel.spring.boot.actuate.console.CamelDevConsoleAutoConfiguration
 org.apache.camel.spring.boot.actuate.endpoint.CamelRouteControllerEndpointAutoConfiguration
 org.apache.camel.spring.boot.actuate.endpoint.CamelRoutesEndpointAutoConfiguration
+org.apache.camel.spring.boot.actuate.health.AsyncHealthIndicatorAutoConfiguration
 org.apache.camel.spring.boot.actuate.health.CamelHealthCheckAutoConfiguration
 org.apache.camel.spring.boot.actuate.health.CamelAvailabilityCheckAutoConfiguration
 org.apache.camel.spring.boot.actuate.info.CamelInfoAutoConfiguration