Add "management.health.probes.enabled" config property

Prior to this commit, we were relying on the
`"spring.main.cloud-platform"` property for overriding cloud platform
detection and enabling liveness and readiness probes. Changes made in
gh-20553 have now been reverted.

This commit adds the `"management.health.probes.enabled"` configuration
property. The auto-configuration now enables the HTTP Probes and
`HealthIndicator` if this property is enabled, or if the Kubernetes
cloud platform is detected.

This property is `false` by default for now, since enabling this for all
Spring Boot applications would be a breaking change. In this case, the
global `"/actuator/health"` endpoint could report `OUT_OF_SERVICE`
during startup time because the application now reports the readiness as
well.

See gh-19593

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/kubernetes/ProbesHealthContributorAutoConfiguration.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.actuate.autoconfigure.kubernetes;
 
 import org.springframework.boot.actuate.autoconfigure.health.ConditionalOnEnabledHealthIndicator;
+import org.springframework.boot.actuate.autoconfigure.kubernetes.ProbesHealthContributorAutoConfiguration.KubernetesOrPropertyCondition;
 import org.springframework.boot.actuate.availability.LivenessProbeHealthIndicator;
 import org.springframework.boot.actuate.availability.ReadinessProbeHealthIndicator;
 import org.springframework.boot.actuate.health.HealthEndpointGroupsRegistryCustomizer;
@@ -24,11 +25,14 @@ import org.springframework.boot.actuate.kubernetes.ProbesHealthEndpointGroupsReg
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.availability.ApplicationAvailabilityAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnCloudPlatform;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.availability.ApplicationAvailabilityProvider;
 import org.springframework.boot.cloud.CloudPlatform;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 
 /**
@@ -39,7 +43,7 @@ import org.springframework.context.annotation.Configuration;
  * @since 2.3.0
  */
 @Configuration(proxyBeanMethods = false)
-@ConditionalOnCloudPlatform(CloudPlatform.KUBERNETES)
+@Conditional(KubernetesOrPropertyCondition.class)
 @AutoConfigureAfter(ApplicationAvailabilityAutoConfiguration.class)
 public class ProbesHealthContributorAutoConfiguration {
 
@@ -64,4 +68,22 @@ public class ProbesHealthContributorAutoConfiguration {
 		return new ProbesHealthEndpointGroupsRegistrar();
 	}
 
+	static class KubernetesOrPropertyCondition extends AnyNestedCondition {
+
+		KubernetesOrPropertyCondition() {
+			super(ConfigurationPhase.PARSE_CONFIGURATION);
+		}
+
+		@ConditionalOnCloudPlatform(CloudPlatform.KUBERNETES)
+		static class Kubernetes {
+
+		}
+
+		@ConditionalOnProperty(prefix = "management.health.probes", name = "enabled")
+		static class ProbesIndicatorsEnabled {
+
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -146,6 +146,12 @@
       "description": "Whether to enable ping health check.",
       "defaultValue": true
     },
+    {
+      "name": "management.health.probes.enabled",
+      "type": "java.lang.Boolean",
+      "description": "Whether to enable liveness and readiness probes.",
+      "defaultValue": false
+    },
     {
       "name": "management.health.rabbit.enabled",
       "type": "java.lang.Boolean",

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/kubernetes/ProbesHealthContributorAutoConfigurationTests.java

@@ -47,8 +47,8 @@ class ProbesHealthContributorAutoConfigurationTests {
 	}
 
 	@Test
-	void probesConfiguredIfKubernetes() {
-		this.contextRunner.withPropertyValues("spring.main.cloud-platform=kubernetes")
+	void probesConfiguredIfProperty() {
+		this.contextRunner.withPropertyValues("management.health.probes.enabled=true")
 				.run((context) -> assertThat(context).hasSingleBean(ApplicationAvailabilityProvider.class)
 						.hasSingleBean(LivenessProbeHealthIndicator.class)
 						.hasSingleBean(ReadinessProbeHealthIndicator.class)

spring-boot-project/spring-boot-docs/src/docs/asciidoc/deployment.adoc

@@ -184,7 +184,7 @@ TIP: The https://github.com/pivotal-cf/java-cfenv/[Java CFEnv] project is a bett
 [[cloud-deployment-kubernetes]]
 === Kubernetes
 Spring Boot auto-detects Kubernetes deployment environments by checking the environment for `"*_SERVICE_HOST"` and `"*_SERVICE_PORT"` variables.
-You can override this detection with the configprop:spring.main.cloud-platform[] configuration property.
+You can override this detection with the configprop:management.health.probes.enabled[] configuration property.
 
 Spring Boot helps you to <<spring-boot-features.adoc#boot-features-application-availability-state,manage the state of your application>> and export it with <<production-ready-features.adoc#production-ready-kubernetes-probes, HTTP Kubernetes Probes using Actuator>>.