code: /*
   * 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.configuration.configmap;
  
  import io.fabric8.kubernetes.api.model.ConfigMap;
  import io.fabric8.kubernetes.client.KubernetesClientBuilder;
  import io.fabric8.kubernetes.client.informers.cache.Lister;
  import lombok.extern.slf4j.Slf4j;
  
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  @Slf4j
  public class ConfigurationConfigmapInformer {
      private final Lister<ConfigMap> configMapLister;
  
      public ConfigurationConfigmapInformer(ConfigmapConfigurationSettings settings) {
          final var client = new KubernetesClientBuilder().build();
          final var informer = client
              .configMaps()
              .inNamespace(settings.getNamespace())
              .withLabelSelector(settings.getLabelSelector())
              .inform();
  
          configMapLister = new Lister<>(informer.getIndexer());
  
          Runtime.getRuntime().addShutdownHook(new Thread(() -> {
              informer.stop();
              client.close();
          }));
      }
  
      public Map<String, String> configMapData() {
          Map<String, String> configMapData = new HashMap<>();
          if (configMapLister != null) {
              final List<ConfigMap> list = configMapLister.list();
              if (list != null) {
                  list.forEach(cf -> {
                      Map<String, String> data = cf.getData();
                      if (data == null) {
                          return;
                      }
                      configMapData.putAll(data);
                  });
              }
          }
  
          return configMapData;
      }
  }
  