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.library.kubernetes;
  
  import com.google.common.cache.CacheBuilder;
  import com.google.common.cache.CacheLoader;
  import com.google.common.cache.LoadingCache;
  import io.fabric8.kubernetes.api.model.Pod;
  import io.fabric8.kubernetes.client.KubernetesClientBuilder;
  import lombok.SneakyThrows;
  
  import java.time.Duration;
  import java.util.Optional;
  
  public enum KubernetesPods {
      INSTANCE;
  
      private final LoadingCache<String, Optional<Pod>> podByIP;
      private final LoadingCache<ObjectID, Optional<Pod>> podByObjectID;
  
      @SneakyThrows
      KubernetesPods() {
          final CacheBuilder<Object, Object> cacheBuilder =
                  CacheBuilder.newBuilder()
                          .expireAfterAccess(Duration.ofMinutes(5));
  
          podByIP = cacheBuilder.build(new CacheLoader<>() {
              @Override
              public Optional<Pod> load(String ip) {
                  try (final var kubernetesClient = new KubernetesClientBuilder().build()) {
                      return kubernetesClient
                              .pods()
                              .inAnyNamespace()
                              .withField("status.podIP", ip)
                              .list()
                              .getItems()
                              .stream()
                              .findFirst();
                  }
              }
          });
  
          podByObjectID = cacheBuilder.build(new CacheLoader<>() {
              @Override
              public Optional<Pod> load(ObjectID objectID) {
                  try (final var kubernetesClient = new KubernetesClientBuilder().build()) {
                      return Optional.ofNullable(
                              kubernetesClient
                                      .pods()
                                      .inNamespace(objectID.namespace())
                                      .withName(objectID.name())
                                      .get());
                  }
              }
          });
      }
  
      @SneakyThrows
      public Optional<Pod> findByIP(final String ip) {
          return podByIP.get(ip);
      }
  
      @SneakyThrows
      public Optional<Pod> findByObjectID(final ObjectID id) {
          return podByObjectID.get(id);
      }
  }
  