feat: make health checks addable via SPI

src/main/java/io/neonbee/NeonBee.java

@@ -23,6 +23,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.ServiceLoader;
 import java.util.Set;
 import java.util.TimeZone;
 import java.util.UUID;
@@ -45,6 +46,7 @@
 import io.neonbee.entity.EntityModelManager;
 import io.neonbee.entity.EntityWrapper;
 import io.neonbee.health.HazelcastClusterHealthCheck;
+import io.neonbee.health.HealthCheckProvider;
 import io.neonbee.health.HealthCheckRegistry;
 import io.neonbee.health.MemoryHealthCheck;
 import io.neonbee.health.internal.HealthCheck;
@@ -328,7 +330,8 @@ private Future<Void> boot() {
      *
      * @return a Future
      */
-    private Future<Void> registerHealthChecks() {
+    @VisibleForTesting
+    Future<Void> registerHealthChecks() {
         List<Future<HealthCheck>> healthChecks = new ArrayList<>();
 
         if (Optional.ofNullable(config.getHealthConfig()).map(HealthConfig::isEnabled).orElse(true)) {
@@ -337,6 +340,12 @@ private Future<Void> registerHealthChecks() {
             if (options.isClustered()) {
                 healthChecks.add(healthRegistry.register(new HazelcastClusterHealthCheck(this, clusterManager)));
             }
+
+            ServiceLoader.load(HealthCheckProvider.class).forEach(provider -> provider.get(vertx).forEach(check -> {
+                if (!healthRegistry.getHealthChecks().containsKey(check.getId())) {
+                    healthChecks.add(healthRegistry.register(check));
+                }
+            }));
         }
 
         return joinComposite(healthChecks).recover(v -> {

src/main/java/io/neonbee/health/AbstractHealthCheck.java

@@ -47,7 +47,7 @@ public AbstractHealthCheck(NeonBee neonBee) {
      *
      * @return a function which returns a handler with a Status
      */
-    abstract Function<NeonBee, Handler<Promise<Status>>> createProcedure();
+    public abstract Function<NeonBee, Handler<Promise<Status>>> createProcedure();
 
     @Override
     public long getRetentionTime() {

src/main/java/io/neonbee/health/HazelcastClusterHealthCheck.java

@@ -45,7 +45,7 @@ public boolean isGlobal() {
     }
 
     @Override
-    Function<NeonBee, Handler<Promise<Status>>> createProcedure() {
+    public Function<NeonBee, Handler<Promise<Status>>> createProcedure() {
         return neonBee -> healthCheckPromise -> neonBee.getVertx().executeBlocking(promise -> {
             HazelcastInstance instance = clusterManager.getHazelcastInstance();
             boolean lifecycleServiceRunning = instance.getLifecycleService().isRunning();

src/main/java/io/neonbee/health/HealthCheckProvider.java

@@ -0,0 +1,21 @@
+package io.neonbee.health;
+
+import java.util.List;
+
+import io.vertx.core.Vertx;
+
+/**
+ * This interface can be used to provide additional health checks to NeonBee. If you implement this interface, NeonBee
+ * discovers the implementing class and registers all health checks of the list to NeonBee's health check registry.
+ */
+@FunctionalInterface
+public interface HealthCheckProvider {
+
+    /**
+     * Provide custom health checks that will be registered to NeonBee's health check registry.
+     *
+     * @param vertx the current Vert.x instance
+     * @return a succeeded future if registering was successful. A failed Future, otherwise.
+     */
+    List<AbstractHealthCheck> get(Vertx vertx);
+}

src/main/java/io/neonbee/health/MemoryHealthCheck.java

@@ -50,7 +50,7 @@ public boolean isGlobal() {
     }
 
     @Override
-    Function<NeonBee, Handler<Promise<Status>>> createProcedure() {
+    public Function<NeonBee, Handler<Promise<Status>>> createProcedure() {
         return neonBee -> healthCheckPromise -> {
             long usedMemory = memoryStats.getUsedHeap();
             double memoryUsedOfTotalPercentage = (PERCENTAGE_MULTIPLIER * usedMemory) / memoryStats.getCommittedHeap();

src/test/java/io/neonbee/NeonBeeTest.java

@@ -11,6 +11,7 @@
 import static io.neonbee.NeonBeeProfile.STABLE;
 import static io.neonbee.internal.helper.StringHelper.EMPTY;
 import static io.neonbee.test.helper.OptionsHelper.defaultOptions;
+import static io.neonbee.test.helper.ResourceHelper.TEST_RESOURCES;
 import static io.vertx.core.Future.failedFuture;
 import static io.vertx.core.Future.succeededFuture;
 import static org.mockito.ArgumentMatchers.any;
@@ -22,8 +23,13 @@
 
 import java.io.IOException;
 import java.lang.reflect.Method;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Function;
@@ -44,6 +50,13 @@
 import org.mockito.Mockito;
 
 import io.neonbee.config.NeonBeeConfig;
+import io.neonbee.health.DummyHealthCheck;
+import io.neonbee.health.DummyHealthCheckProvider;
+import io.neonbee.health.HazelcastClusterHealthCheck;
+import io.neonbee.health.HealthCheckProvider;
+import io.neonbee.health.HealthCheckRegistry;
+import io.neonbee.health.MemoryHealthCheck;
+import io.neonbee.health.internal.HealthCheck;
 import io.neonbee.internal.NeonBeeModuleJar;
 import io.neonbee.internal.tracking.MessageDirection;
 import io.neonbee.internal.tracking.TrackingDataLoggingStrategy;
@@ -79,6 +92,10 @@ protected void adaptOptions(TestInfo testInfo, NeonBeeOptions.Mutable options) {
             options.addActiveProfile(CORE);
             options.setIgnoreClassPath(false);
             break;
+        case "testRegisterClusterHealthChecks":
+            options.setClustered(true);
+            options.setClusterConfigResource("hazelcast-local.xml");
+            break;
         case "testDeployModule":
             try {
                 options.setModuleJarPaths(
@@ -202,6 +219,72 @@ void testRegisterAndUnregisterLocalConsumer() {
         assertThat(getNeonBee().isLocalConsumerAvailable(address)).isFalse();
     }
 
+    @Test
+    @DisplayName("NeonBee should register all default health checks")
+    void testRegisterDefaultHealthChecks() {
+        Map<String, HealthCheck> registeredChecks = getNeonBee().getHealthCheckRegistry().getHealthChecks();
+        assertThat(registeredChecks.size()).isEqualTo(1);
+        assertThat(registeredChecks.containsKey("node." + getNeonBee().getNodeId() + "." + MemoryHealthCheck.NAME))
+                .isTrue();
+    }
+
+    @Test
+    @DisplayName("NeonBee should register all cluster + default health checks if started clustered")
+    void testRegisterClusterHealthChecks() {
+        Map<String, HealthCheck> registeredChecks = getNeonBee().getHealthCheckRegistry().getHealthChecks();
+        assertThat(registeredChecks.size()).isEqualTo(2);
+        assertThat(registeredChecks.containsKey(HazelcastClusterHealthCheck.NAME)).isTrue();
+    }
+
+    @Test
+    @Timeout(value = 1, timeUnit = TimeUnit.SECONDS)
+    @DisplayName("NeonBee should register all SPI-provided + default health checks")
+    void testRegisterSpiAndDefaultHealthChecks(VertxTestContext testContext) {
+        HealthCheckRegistry registry = getNeonBee().getHealthCheckRegistry();
+        Set<String> healthCheckMap = registry.getHealthChecks().keySet();
+        for (String checkId : healthCheckMap) {
+            registry.unregister(checkId);
+        }
+
+        runWithMetaInfService(HealthCheckProvider.class, DummyHealthCheckProvider.class.getName(), testContext, () -> {
+            getNeonBee().registerHealthChecks().onComplete(testContext.succeeding(v -> testContext.verify(() -> {
+                Map<String, HealthCheck> registeredChecks = registry.getHealthChecks();
+                assertThat(registeredChecks.size()).isEqualTo(2);
+                assertThat(
+                        registeredChecks.containsKey("node." + getNeonBee().getNodeId() + "." + MemoryHealthCheck.NAME))
+                                .isTrue();
+                assertThat(registeredChecks.containsKey(DummyHealthCheck.DUMMY_ID)).isTrue();
+                testContext.completeNow();
+            })));
+        });
+    }
+
+    private void runWithMetaInfService(Class<?> service, String content, VertxTestContext context, Runnable runnable) {
+        Path providerPath = TEST_RESOURCES.resolve("META-INF/services/" + service.getName());
+        ClassLoader classLoader;
+        try {
+            Files.write(providerPath, content.getBytes(StandardCharsets.UTF_8));
+            classLoader = new URLClassLoader(new URL[] { TEST_RESOURCES.resolve(".").toUri().toURL() });
+        } catch (IOException e) {
+            context.failNow(e);
+            return;
+        }
+        Thread thread = Thread.currentThread();
+        ClassLoader original = thread.getContextClassLoader();
+        thread.setContextClassLoader(classLoader);
+
+        try {
+            runnable.run();
+        } finally {
+            thread.setContextClassLoader(original);
+            try {
+                Files.deleteIfExists(providerPath);
+            } catch (IOException e) {
+                context.failNow(e);
+            }
+        }
+    }
+
     @Test
     @DisplayName("NeonBee should have a (unique) node id")
     void testGetNodeId() {

src/test/java/io/neonbee/health/AbstractHealthCheckTest.java

@@ -162,7 +162,7 @@ void testConfigRetrievalFails(VertxTestContext testContext) {
     private AbstractHealthCheck createDummyHealthCheck(boolean global, boolean ok, JsonObject data) {
         return new AbstractHealthCheck(NeonBee.get(vertxMock)) {
             @Override
-            Function<NeonBee, Handler<Promise<Status>>> createProcedure() {
+            public Function<NeonBee, Handler<Promise<Status>>> createProcedure() {
                 return nb -> p -> p.complete(new Status().setOk(ok).setData(data));
             }
 

src/test/java/io/neonbee/health/DummyHealthCheck.java

@@ -0,0 +1,39 @@
+package io.neonbee.health;
+
+import java.util.function.Function;
+
+import io.neonbee.NeonBee;
+import io.vertx.core.Handler;
+import io.vertx.core.Promise;
+import io.vertx.ext.healthchecks.Status;
+
+public class DummyHealthCheck extends AbstractHealthCheck {
+    /**
+     * Name of the health check.
+     */
+    public static final String DUMMY_ID = "dummy";
+
+    /**
+     * Constructs an instance of {@link AbstractHealthCheck}.
+     *
+     * @param neonBee the current NeonBee instance
+     */
+    public DummyHealthCheck(NeonBee neonBee) {
+        super(neonBee);
+    }
+
+    @Override
+    public Function<NeonBee, Handler<Promise<Status>>> createProcedure() {
+        return nb -> promise -> promise.complete(new Status().setOK());
+    }
+
+    @Override
+    public String getId() {
+        return DUMMY_ID;
+    }
+
+    @Override
+    public boolean isGlobal() {
+        return true;
+    }
+}

src/test/java/io/neonbee/health/DummyHealthCheckProvider.java

@@ -0,0 +1,13 @@
+package io.neonbee.health;
+
+import java.util.List;
+
+import io.neonbee.NeonBee;
+import io.vertx.core.Vertx;
+
+public class DummyHealthCheckProvider implements HealthCheckProvider {
+    @Override
+    public List<AbstractHealthCheck> get(Vertx vertx) {
+        return List.of(new DummyHealthCheck(NeonBee.get(vertx)));
+    }
+}

src/test/java/io/neonbee/health/HealthCheckRegistryTest.java

@@ -1,6 +1,7 @@
 package io.neonbee.health;
 
 import static com.google.common.truth.Truth.assertThat;
+import static io.neonbee.health.DummyHealthCheck.DUMMY_ID;
 import static io.neonbee.test.helper.OptionsHelper.defaultOptions;
 import static io.neonbee.test.helper.ReflectionHelper.setValueOfPrivateField;
 import static org.junit.jupiter.api.Assertions.assertThrows;
@@ -33,8 +34,6 @@
 import io.neonbee.internal.verticle.HealthCheckVerticle;
 import io.neonbee.test.helper.DeploymentHelper;
 import io.vertx.core.Future;
-import io.vertx.core.Handler;
-import io.vertx.core.Promise;
 import io.vertx.core.Vertx;
 import io.vertx.core.json.JsonArray;
 import io.vertx.core.json.JsonObject;
@@ -47,34 +46,10 @@
 
 @ExtendWith(VertxExtension.class)
 class HealthCheckRegistryTest {
-
-    private static final String DUMMY_ID = "dummy-group.check-0";
-
     private static final long RETENTION_TIME = 12L;
 
     private NeonBee neonBee;
 
-    private static class DummyCheck extends AbstractHealthCheck {
-        DummyCheck(NeonBee neonBee) {
-            super(neonBee);
-        }
-
-        @Override
-        Function<NeonBee, Handler<Promise<Status>>> createProcedure() {
-            return nb -> p -> p.complete(new Status().setOK());
-        }
-
-        @Override
-        public String getId() {
-            return DUMMY_ID;
-        }
-
-        @Override
-        public boolean isGlobal() {
-            return true;
-        }
-    }
-
     @BeforeEach
     @Timeout(value = 2, timeUnit = TimeUnit.SECONDS)
     void setUp(Vertx vertx) {
@@ -168,7 +143,7 @@ void testCustomConfigDisabled(Vertx vertx) throws HealthCheckException {
     void testUnregister(VertxTestContext testContext) {
         HealthCheckRegistry registry = neonBee.getHealthCheckRegistry();
         registry.healthChecks = spy(registry.healthChecks);
-        AbstractHealthCheck check = new DummyCheck(neonBee);
+        AbstractHealthCheck check = new DummyHealthCheck(neonBee);
 
         registry.register(check).compose(v -> {
             testContext.verify(() -> {
@@ -234,7 +209,7 @@ public Future<JsonArray> retrieveData(DataQuery query, DataContext context) {
         DeploymentHelper.undeployAllVerticlesOfClass(neonBee.getVertx(), HealthCheckVerticle.class)
                 .compose(v -> AsyncHelper.allComposite(
                         List.of(vertx.deployVerticle(healthCheckVerticle1), vertx.deployVerticle(healthCheckVerticle2),
-                                neonBee.getHealthCheckRegistry().register(new DummyCheck(neonBee)))))
+                                neonBee.getHealthCheckRegistry().register(new DummyHealthCheck(neonBee)))))
                 .onSuccess(v -> {
                     neonBee.getHealthCheckRegistry().collectHealthCheckResults()
                             .onComplete(testContext.succeeding(result -> testContext.verify(() -> {
@@ -266,7 +241,7 @@ Future<List<JsonObject>> getLocalHealthCheckResults() {
             }
         };
 
-        mock.register(new DummyCheck(neonBee)).compose(hc -> mock.collectHealthCheckResults())
+        mock.register(new DummyHealthCheck(neonBee)).compose(hc -> mock.collectHealthCheckResults())
                 .onComplete(testContext.succeeding(result -> testContext.verify(() -> {
                     Function<String, Long> matchingNameCount = id -> result.getJsonArray("checks").stream()
                             .filter(c -> ((JsonObject) c).getString("id").equals(id)).count();