Polish "Add Prometheus push gateway support"

Rework Prometheus push gateway support so that the central class can
be used outside of auto-configuration. The shutdown flags have also
been replaced with a single "shutdown-operation" property since it's
unlikely that both "push" and "delete" will be required.

It's also possible now to supply a `TaskScheduler` to the manager.

See gh-14353

Author: philwebb

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/export/prometheus/PrometheusMetricsExportAutoConfiguration.java

@@ -16,25 +16,21 @@
 
 package org.springframework.boot.actuate.autoconfigure.metrics.export.prometheus;
 
-import java.net.UnknownHostException;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.TimeUnit;
-
-import javax.annotation.PreDestroy;
+import java.time.Duration;
+import java.util.Map;
 
 import io.micrometer.core.instrument.Clock;
 import io.micrometer.prometheus.PrometheusConfig;
 import io.micrometer.prometheus.PrometheusMeterRegistry;
 import io.prometheus.client.CollectorRegistry;
 import io.prometheus.client.exporter.PushGateway;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 import org.springframework.boot.actuate.autoconfigure.endpoint.condition.ConditionalOnEnabledEndpoint;
 import org.springframework.boot.actuate.autoconfigure.metrics.CompositeMeterRegistryAutoConfiguration;
 import org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfiguration;
 import org.springframework.boot.actuate.autoconfigure.metrics.export.simple.SimpleMetricsExportAutoConfiguration;
+import org.springframework.boot.actuate.metrics.export.prometheus.PrometheusPushGatewayManager;
+import org.springframework.boot.actuate.metrics.export.prometheus.PrometheusPushGatewayManager.ShutdownOperation;
 import org.springframework.boot.actuate.metrics.export.prometheus.PrometheusScrapeEndpoint;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.AutoConfigureBefore;
@@ -53,6 +49,7 @@
  *
  * @since 2.0.0
  * @author Jon Schneider
+ * @author David J. M. Karlsen
  */
 @Configuration
 @AutoConfigureBefore({ CompositeMeterRegistryAutoConfiguration.class,
@@ -100,108 +97,42 @@ public PrometheusScrapeEndpoint prometheusEndpoint(
 	/**
 	 * Configuration for <a href="https://github.com/prometheus/pushgateway">Prometheus
 	 * Pushgateway</a>.
-	 *
-	 * @author David J. M. Karlsen
 	 */
 	@Configuration
 	@ConditionalOnClass(PushGateway.class)
 	@ConditionalOnProperty(prefix = "management.metrics.export.prometheus.pushgateway", name = "enabled")
 	public static class PrometheusPushGatewayConfiguration {
 
+		/**
+		 * The fallback job name. We use 'spring' since there's a history of Prometheus
+		 * spring integration defaulting to that name from when Prometheus integration
+		 * didn't exist in Spring itself.
+		 */
+		private static final String FALLBACK_JOB = "spring";
+
 		@Bean
-		public PushGatewayHandler pushGatewayHandler(CollectorRegistry collectorRegistry,
+		@ConditionalOnMissingBean
+		public PrometheusPushGatewayManager prometheusPushGatewayManager(
+				CollectorRegistry collectorRegistry,
 				PrometheusProperties prometheusProperties, Environment environment) {
-			return new PushGatewayHandler(collectorRegistry, prometheusProperties,
-					environment);
+			PrometheusProperties.Pushgateway properties = prometheusProperties
+					.getPushgateway();
+			PushGateway pushGateway = new PushGateway(properties.getBaseUrl());
+			Duration pushRate = properties.getPushRate();
+			String job = getJob(properties, environment);
+			Map<String, String> groupingKey = properties.getGroupingKey();
+			ShutdownOperation shutdownOperation = properties.getShutdownOperation();
+			return new PrometheusPushGatewayManager(pushGateway, collectorRegistry,
+					pushRate, job, groupingKey, shutdownOperation);
 		}
 
-		static class PushGatewayHandler {
-
-			private final Logger logger = LoggerFactory
-					.getLogger(PrometheusPushGatewayConfiguration.class);
-
-			private final CollectorRegistry collectorRegistry;
-
-			private final PrometheusProperties.PushgatewayProperties pushgatewayProperties;
-
-			private final PushGateway pushGateway;
-
-			private final Environment environment;
-
-			private final ScheduledExecutorService executorService;
-
-			PushGatewayHandler(CollectorRegistry collectorRegistry,
-					PrometheusProperties prometheusProperties, Environment environment) {
-				this.collectorRegistry = collectorRegistry;
-				this.pushgatewayProperties = prometheusProperties.getPushgateway();
-				this.pushGateway = new PushGateway(
-						this.pushgatewayProperties.getBaseUrl());
-				this.environment = environment;
-				this.executorService = Executors.newSingleThreadScheduledExecutor((r) -> {
-					Thread thread = new Thread(r);
-					thread.setDaemon(true);
-					thread.setName("micrometer-pushgateway");
-					return thread;
-				});
-				this.executorService.scheduleAtFixedRate(this::push, 0,
-						this.pushgatewayProperties.getPushRate().toMillis(),
-						TimeUnit.MILLISECONDS);
-			}
-
-			void push() {
-				try {
-					this.pushGateway.pushAdd(this.collectorRegistry, getJobName(),
-							this.pushgatewayProperties.getGroupingKeys());
-				}
-				catch (UnknownHostException ex) {
-					this.logger.error("Unable to locate host '"
-							+ this.pushgatewayProperties.getBaseUrl()
-							+ "'. No longer attempting metrics publication to this host");
-					this.executorService.shutdown();
-				}
-				catch (Throwable throwable) {
-					this.logger.error("Unable to push metrics to Prometheus Pushgateway",
-							throwable);
-				}
-			}
-
-			@PreDestroy
-			void shutdown() {
-				this.executorService.shutdown();
-				if (this.pushgatewayProperties.isPushOnShutdown()) {
-					push();
-				}
-				if (this.pushgatewayProperties.isDeleteOnShutdown()) {
-					delete();
-				}
-			}
-
-			private void delete() {
-				try {
-					this.pushGateway.delete(getJobName(),
-							this.pushgatewayProperties.getGroupingKeys());
-				}
-				catch (Throwable throwable) {
-					this.logger.error(
-							"Unable to delete metrics from Prometheus Pushgateway",
-							throwable);
-				}
-			}
-
-			private String getJobName() {
-				String job = this.pushgatewayProperties.getJob();
-				if (job == null) {
-					job = this.environment.getProperty("spring.application.name");
-				}
-				if (job == null) {
-					// There's a history of Prometheus spring integration defaulting the
-					// getJobName name to "spring" from when
-					// Prometheus integration didn't exist in Spring itself.
-					job = "spring";
-				}
-				return job;
-			}
-
+		private String getJob(PrometheusProperties.Pushgateway properties,
+				Environment environment) {
+			String job = properties.getJob();
+			job = (job != null) ? job
+					: environment.getProperty("spring.application.name");
+			job = (job != null) ? job : FALLBACK_JOB;
+			return job;
 		}
 
 	}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/export/prometheus/PrometheusProperties.java

@@ -20,6 +20,7 @@
 import java.util.HashMap;
 import java.util.Map;
 
+import org.springframework.boot.actuate.metrics.export.prometheus.PrometheusPushGatewayManager.ShutdownOperation;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
 /**
@@ -42,7 +43,7 @@ public class PrometheusProperties {
 	 * Configuration options for using Prometheus Pushgateway, allowing metrics to be
 	 * pushed when they cannot be scraped.
 	 */
-	private PushgatewayProperties pushgateway = new PushgatewayProperties();
+	private Pushgateway pushgateway = new Pushgateway();
 
 	/**
 	 * Step size (i.e. reporting frequency) to use.
@@ -65,53 +66,48 @@ public void setStep(Duration step) {
 		this.step = step;
 	}
 
-	public PushgatewayProperties getPushgateway() {
+	public Pushgateway getPushgateway() {
 		return this.pushgateway;
 	}
 
-	public void setPushgateway(PushgatewayProperties pushgateway) {
+	public void setPushgateway(Pushgateway pushgateway) {
 		this.pushgateway = pushgateway;
 	}
 
 	/**
 	 * Configuration options for push-based interaction with Prometheus.
 	 */
-	public static class PushgatewayProperties {
+	public static class Pushgateway {
 
 		/**
 		 * Enable publishing via a Prometheus Pushgateway.
 		 */
 		private Boolean enabled = false;
 
 		/**
-		 * Required host:port or ip:port of the Pushgateway.
+		 * Base URL for the Pushgateway.
 		 */
 		private String baseUrl = "localhost:9091";
 
 		/**
-		 * Required identifier for this application instance.
-		 */
-		private String job;
-
-		/**
-		 * Frequency with which to push metrics to Pushgateway.
+		 * Frequency with which to push metrics.
 		 */
 		private Duration pushRate = Duration.ofMinutes(1);
 
 		/**
-		 * Push metrics right before shut-down. Mostly useful for batch jobs.
+		 * Job identifier for this application instance.
 		 */
-		private boolean pushOnShutdown = true;
+		private String job;
 
 		/**
-		 * Delete metrics from Pushgateway when application is shut-down.
+		 * Grouping key for the pushed metrics.
 		 */
-		private boolean deleteOnShutdown = true;
+		private Map<String, String> groupingKey = new HashMap<>();
 
 		/**
-		 * Used to group metrics in pushgateway. A common example is setting
+		 * Operation that should be performed on shutdown.
 		 */
-		private Map<String, String> groupingKeys = new HashMap<>();
+		private ShutdownOperation shutdownOperation = ShutdownOperation.NONE;
 
 		public Boolean getEnabled() {
 			return this.enabled;
@@ -129,14 +125,6 @@ public void setBaseUrl(String baseUrl) {
 			this.baseUrl = baseUrl;
 		}
 
-		public String getJob() {
-			return this.job;
-		}
-
-		public void setJob(String job) {
-			this.job = job;
-		}
-
 		public Duration getPushRate() {
 			return this.pushRate;
 		}
@@ -145,28 +133,28 @@ public void setPushRate(Duration pushRate) {
 			this.pushRate = pushRate;
 		}
 
-		public boolean isPushOnShutdown() {
-			return this.pushOnShutdown;
+		public String getJob() {
+			return this.job;
 		}
 
-		public void setPushOnShutdown(boolean pushOnShutdown) {
-			this.pushOnShutdown = pushOnShutdown;
+		public void setJob(String job) {
+			this.job = job;
 		}
 
-		public boolean isDeleteOnShutdown() {
-			return this.deleteOnShutdown;
+		public Map<String, String> getGroupingKey() {
+			return this.groupingKey;
 		}
 
-		public void setDeleteOnShutdown(boolean deleteOnShutdown) {
-			this.deleteOnShutdown = deleteOnShutdown;
+		public void setGroupingKey(Map<String, String> groupingKey) {
+			this.groupingKey = groupingKey;
 		}
 
-		public Map<String, String> getGroupingKeys() {
-			return this.groupingKeys;
+		public ShutdownOperation getShutdownOperation() {
+			return this.shutdownOperation;
 		}
 
-		public void setGroupingKeys(Map<String, String> groupingKeys) {
-			this.groupingKeys = groupingKeys;
+		public void setShutdownOperation(ShutdownOperation shutdownOperation) {
+			this.shutdownOperation = shutdownOperation;
 		}
 
 	}

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/export/prometheus/PrometheusMetricsExportAutoConfigurationTests.java

@@ -22,8 +22,8 @@
 import io.prometheus.client.CollectorRegistry;
 import org.junit.Test;
 
-import org.springframework.boot.actuate.autoconfigure.metrics.export.prometheus.PrometheusMetricsExportAutoConfiguration.PrometheusPushGatewayConfiguration;
 import org.springframework.boot.actuate.autoconfigure.web.server.ManagementContextAutoConfiguration;
+import org.springframework.boot.actuate.metrics.export.prometheus.PrometheusPushGatewayManager;
 import org.springframework.boot.actuate.metrics.export.prometheus.PrometheusScrapeEndpoint;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
@@ -137,8 +137,8 @@ public void withPushGatewayEnabled() {
 				.withPropertyValues(
 						"management.metrics.export.prometheus.pushgateway.enabled=true")
 				.withUserConfiguration(BaseConfiguration.class)
-				.run((context) -> assertThat(context).hasSingleBean(
-						PrometheusPushGatewayConfiguration.PushGatewayHandler.class));
+				.run((context) -> assertThat(context)
+						.hasSingleBean(PrometheusPushGatewayManager.class));
 	}
 
 	@Configuration

spring-boot-project/spring-boot-actuator/pom.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 	<parent>
@@ -61,6 +62,11 @@
 			<artifactId>micrometer-registry-prometheus</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>io.prometheus</groupId>
+			<artifactId>simpleclient_pushgateway</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>io.reactivex</groupId>
 			<artifactId>rxjava-reactive-streams</artifactId>