Merge branch '2.2.x'

Closes gh-21092

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/actuate/metrics/MetricsHealthMicrometerExportExample.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2012-2020 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.boot.docs.actuate.metrics;
+
+import io.micrometer.core.instrument.Gauge;
+import io.micrometer.core.instrument.MeterRegistry;
+
+import org.springframework.boot.actuate.health.HealthEndpoint;
+import org.springframework.boot.actuate.health.HealthIndicator;
+import org.springframework.boot.actuate.health.Status;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Example to show how to export {@link HealthIndicator} beans to a {@link MeterRegistry}.
+ *
+ * @author Phillip Webb
+ */
+public class MetricsHealthMicrometerExportExample {
+
+	// tag::configuration[]
+	@Configuration
+	public class HealthMetricsConfiguration {
+
+		public HealthMetricsConfiguration(MeterRegistry registry, HealthEndpoint healthEndpoint) {
+			// This example presumes common tags (such as the app) are applied elsewhere
+			Gauge.builder("health", healthEndpoint, this::getStatusCode).strongReference(true).register(registry);
+		}
+
+		private int getStatusCode(HealthEndpoint health) {
+			Status status = health.health().getStatus();
+			if (Status.UP.equals(status)) {
+				return 3;
+			}
+			if (Status.OUT_OF_SERVICE.equals(status)) {
+				return 2;
+			}
+			if (Status.DOWN.equals(status)) {
+				return 1;
+			}
+			return 0;
+		}
+
+	}
+	// end::configuration[]
+
+}