Fix potential NPE in the AlarmStatusQueryHandler. (#13513)

Author: wankai123

docs/en/changes/changes.md

@@ -100,6 +100,7 @@
 * Refactor Kubernetes coordinator to be more accurate about node readiness.
 * Bump up netty to 4.2.5.Final.
 * BanyanDB: fix log query missing order by condition, and fix missing service id condition when query by instance id or endpoint id.
+* Fix potential NPE in the `AlarmStatusQueryHandler`.
 
 #### UI
 

oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/AlarmModuleProvider.java

@@ -25,6 +25,7 @@
 import org.apache.skywalking.oap.server.configuration.api.DynamicConfigurationService;
 import org.apache.skywalking.oap.server.core.CoreModule;
 import org.apache.skywalking.oap.server.core.alarm.AlarmModule;
+import org.apache.skywalking.oap.server.core.alarm.AlarmRulesWatcherService;
 import org.apache.skywalking.oap.server.core.alarm.AlarmStandardPersistence;
 import org.apache.skywalking.oap.server.core.alarm.MetricsNotify;
 import org.apache.skywalking.oap.server.library.module.ModuleDefine;
@@ -59,6 +60,7 @@ public void prepare() throws ServiceNotProvidedException, ModuleStartException {
         alarmRulesWatcher = new AlarmRulesWatcher(new Rules(), this, getManager());
         notifyHandler = new NotifyHandler(alarmRulesWatcher, getManager());
         this.registerServiceImplementation(MetricsNotify.class, notifyHandler);
+        this.registerServiceImplementation(AlarmRulesWatcherService.class, alarmRulesWatcher);
     }
 
     @Override

oap-server/server-alarm-plugin/src/main/java/org/apache/skywalking/oap/server/core/alarm/provider/AlarmRulesWatcher.java

@@ -31,6 +31,7 @@
 import lombok.extern.slf4j.Slf4j;
 import org.apache.skywalking.oap.server.configuration.api.ConfigChangeWatcher;
 import org.apache.skywalking.oap.server.core.alarm.AlarmModule;
+import org.apache.skywalking.oap.server.core.alarm.AlarmRulesWatcherService;
 import org.apache.skywalking.oap.server.core.alarm.provider.dingtalk.DingtalkSettings;
 import org.apache.skywalking.oap.server.core.alarm.provider.discord.DiscordSettings;
 import org.apache.skywalking.oap.server.core.alarm.provider.feishu.FeishuSettings;
@@ -50,7 +51,7 @@
  * @since 6.5.0
  */
 @Slf4j
-public class AlarmRulesWatcher extends ConfigChangeWatcher {
+public class AlarmRulesWatcher extends ConfigChangeWatcher implements AlarmRulesWatcherService {
     @Getter
     private volatile Map<String, List<RunningRule>> runningContext;
     private volatile Map<AlarmRule, RunningRule> alarmRuleRunningRuleMap;

oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/alarm/AlarmModule.java

@@ -34,6 +34,6 @@ public AlarmModule() {
 
     @Override
     public Class[] services() {
-        return new Class[] {MetricsNotify.class};
+        return new Class[] {MetricsNotify.class, AlarmRulesWatcherService.class};
     }
 }

oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/alarm/AlarmRulesWatcherService.java

@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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
+ *
+ *     http://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.apache.skywalking.oap.server.core.alarm;
+
+import org.apache.skywalking.oap.server.library.module.Service;
+
+public interface AlarmRulesWatcherService extends Service {
+
+}

oap-server/server-query-plugin/status-query-plugin/src/main/java/org/apache/skywalking/oap/query/debug/AlarmStatusQueryHandler.java

@@ -31,8 +31,8 @@
 import java.util.stream.Collectors;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.skywalking.oap.server.core.alarm.AlarmModule;
+import org.apache.skywalking.oap.server.core.alarm.AlarmRulesWatcherService;
 import org.apache.skywalking.oap.server.core.alarm.provider.AlarmEntity;
-import org.apache.skywalking.oap.server.core.alarm.provider.AlarmModuleProvider;
 import org.apache.skywalking.oap.server.core.alarm.provider.AlarmRulesWatcher;
 import org.apache.skywalking.oap.server.core.alarm.provider.RunningRule;
 import org.apache.skywalking.oap.server.core.analysis.metrics.DoubleValueHolder;
@@ -55,10 +55,8 @@ public AlarmStatusQueryHandler(final ModuleManager manager) {
 
     private AlarmRulesWatcher getAlarmRulesWatcher() {
         if (alarmRulesWatcher == null) {
-
-            AlarmModuleProvider provider = (AlarmModuleProvider) moduleManager.find(AlarmModule.NAME)
-                                               .provider();
-            alarmRulesWatcher = provider.getAlarmRulesWatcher();
+            alarmRulesWatcher = (AlarmRulesWatcher) moduleManager.find(AlarmModule.NAME)
+                                                                 .provider().getService(AlarmRulesWatcherService.class);
         }
         return alarmRulesWatcher;
     }
@@ -79,6 +77,9 @@ public HttpResponse getAlarmRuleByName(@Param("ruleName") String ruleName) {
         Map<String, RunningRule> runningRules = getAlarmRulesWatcher().getRunningContext().values().stream().flatMap(List::stream)
                                                                       .collect(Collectors.toMap(RunningRule::getRuleName, r -> r));
         RunningRule rule = runningRules.get(ruleName);
+        if (rule == null) {
+            return HttpResponse.of(MediaType.JSON_UTF_8, "{}");
+        }
         JsonObject runningRuleInfo = new JsonObject();
         runningRuleInfo.addProperty("ruleName", rule.getRuleName());
         runningRuleInfo.addProperty("expression", rule.getExpression());
@@ -137,6 +138,9 @@ public HttpResponse getAlarmRuleContext(@Param("ruleName") String ruleName, @Par
         Map<String, RunningRule> runningRules = getAlarmRulesWatcher().getRunningContext().values().stream().flatMap(List::stream)
                                                                       .collect(Collectors.toMap(RunningRule::getRuleName, r -> r));
         RunningRule rule = runningRules.get(ruleName);
+        if (rule == null) {
+            return HttpResponse.of(MediaType.JSON_UTF_8, "{}");
+        }
         Map<AlarmEntity, RunningRule.Window> windows = rule.getWindows();
         RunningRule.Window window = windows.keySet().stream().filter(e -> e.getName().equals(entityName)).map(windows::get)
             .findFirst().orElse(null);