Add configuration meta-data property for the number of members in the DistributedSystem.

Guard against null/unset URLs for the DistributedSystem standard gemfire properties and security properties locations.

spring-geode-actuator/src/main/java/org/springframework/geode/boot/actuate/GeodeCacheHealthIndicator.java

@@ -17,6 +17,7 @@
 package org.springframework.geode.boot.actuate;
 
 import java.net.URL;
+import java.util.Collection;
 import java.util.Optional;
 import java.util.function.Function;
 
@@ -29,6 +30,7 @@ import org.springframework.boot.actuate.health.Health;
 import org.springframework.boot.actuate.health.HealthIndicator;
 import org.springframework.boot.actuate.health.Status;
 import org.springframework.geode.boot.actuate.health.AbstractGeodeHealthIndicator;
+import org.springframework.util.StringUtils;
 
 /**
  * The {@link GeodeCacheHealthIndicator} class is a Spring Boot {@link HealthIndicator} providing details about
@@ -135,12 +137,23 @@ public class GeodeCacheHealthIndicator extends AbstractGeodeHealthIndicator {
 		return healthBuilder -> getGemFireCache()
 			.map(GemFireCache::getDistributedSystem)
 			.map(distributedSystem -> healthBuilder
+				.withDetail("geode.distributed-system.member-count", Optional.of(distributedSystem)
+					.map(DistributedSystem::getAllOtherMembers)
+					.map(Collection::size)
+					.map(size -> size + 1)
+					.orElse(1))
 				.withDetail("geode.distributed-system.connection", toConnectedNoConnectedString(distributedSystem.isConnected()))
 				.withDetail("geode.distributed-system.reconnecting", toYesNoString(distributedSystem.isReconnecting()))
 				.withDetail("geode.distributed-system.properties-location",
-					Optional.ofNullable(DistributedSystem.getPropertiesFileURL()).map(URL::toExternalForm))
+					Optional.ofNullable(DistributedSystem.getPropertiesFileURL())
+						.map(URL::toExternalForm)
+						.filter(StringUtils::hasText)
+						.orElse(""))
 				.withDetail("geode.distributed-system.security-properties-location",
-					Optional.ofNullable(DistributedSystem.getSecurityPropertiesFileURL()).map(URL::toExternalForm))
+					Optional.ofNullable(DistributedSystem.getSecurityPropertiesFileURL())
+						.map(URL::toExternalForm)
+						.filter(StringUtils::hasText)
+						.orElse(""))
 			)
 			.orElse(healthBuilder);
 	}

spring-geode-actuator/src/test/java/org/springframework/geode/boot/actuate/GeodeCacheHealthIndicatorUnitTests.java

@@ -24,6 +24,9 @@ import static org.mockito.Mockito.when;
 
 import java.util.Arrays;
 import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 
 import org.apache.geode.CancelCriterion;
 import org.apache.geode.cache.GemFireCache;
@@ -70,6 +73,15 @@ public class GeodeCacheHealthIndicatorUnitTests {
 	public void setup() {
 		this.cacheHealthIndicator = new GeodeCacheHealthIndicator(this.mockGemFireCache);
 	}
+
+	@SuppressWarnings("all")
+	private Set<DistributedMember> mockDistributedMembers(int size) {
+
+		return IntStream.range(0, size)
+			.mapToObj(it -> mock(DistributedMember.class))
+			.collect(Collectors.toSet());
+	}
+
 	@Test
 	public void healthCheckCapturesDetails() throws Exception {
 
@@ -81,6 +93,7 @@ public class GeodeCacheHealthIndicatorUnitTests {
 
 		DistributedSystem mockDistributedSystem = CacheMockObjects.mockDistributedSystem(mockDistributedMember);
 
+		when(mockDistributedSystem.getAllOtherMembers()).thenAnswer(invocation -> mockDistributedMembers(8));
 		when(mockDistributedSystem.isConnected()).thenReturn(true);
 		when(mockDistributedSystem.isReconnecting()).thenReturn(false);
 
@@ -118,6 +131,7 @@ public class GeodeCacheHealthIndicatorUnitTests {
 		assertThat(healthDetails).containsEntry("geode.distributed-member.groups", Arrays.asList("TestGroup", "MockGroup"));
 		assertThat(healthDetails).containsEntry("geode.distributed-member.host", "Skullbox");
 		assertThat(healthDetails).containsEntry("geode.distributed-member.process-id", 12345);
+		assertThat(healthDetails).containsEntry("geode.distributed-system.member-count", 9);
 		assertThat(healthDetails).containsEntry("geode.distributed-system.connection", "Connected");
 		assertThat(healthDetails).containsEntry("geode.distributed-system.reconnecting", "No");
 		//assertThat(healthDetails).containsKey("geode.distributed-member.properties-location");