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.cluster.plugin.zookeeper;
  
  import com.google.common.collect.Lists;
  import java.nio.charset.StandardCharsets;
  import java.security.NoSuchAlgorithmException;
  import java.util.List;
  import org.apache.curator.RetryPolicy;
  import org.apache.curator.framework.CuratorFramework;
  import org.apache.curator.framework.CuratorFrameworkFactory;
  import org.apache.curator.framework.api.ACLProvider;
  import org.apache.curator.retry.ExponentialBackoffRetry;
  import org.apache.curator.x.discovery.ServiceDiscovery;
  import org.apache.curator.x.discovery.ServiceDiscoveryBuilder;
  import org.apache.skywalking.oap.server.core.CoreModule;
  import org.apache.skywalking.oap.server.core.cluster.ClusterCoordinator;
  import org.apache.skywalking.oap.server.core.cluster.ClusterModule;
  import org.apache.skywalking.oap.server.core.cluster.ClusterNodesQuery;
  import org.apache.skywalking.oap.server.core.cluster.ClusterRegister;
  import org.apache.skywalking.oap.server.core.cluster.RemoteInstance;
  import org.apache.skywalking.oap.server.library.module.ModuleProvider;
  import org.apache.skywalking.oap.server.library.module.ModuleStartException;
  import org.apache.skywalking.oap.server.library.module.ServiceNotProvidedException;
  import org.apache.skywalking.oap.server.library.util.StringUtil;
  import org.apache.zookeeper.ZooDefs;
  import org.apache.zookeeper.data.ACL;
  import org.apache.zookeeper.data.Id;
  import org.apache.zookeeper.server.auth.DigestAuthenticationProvider;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Use Zookeeper to manage all instances in SkyWalking cluster.
   */
  public class ClusterModuleZookeeperProvider extends ModuleProvider {
  
      private static final Logger LOGGER = LoggerFactory.getLogger(ClusterModuleZookeeperProvider.class);
  
      private static final String BASE_PATH = "/skywalking";
  
      private ClusterModuleZookeeperConfig config;
      private CuratorFramework client;
      private ServiceDiscovery<RemoteInstance> serviceDiscovery;
      private ZookeeperCoordinator coordinator;
  
      public ClusterModuleZookeeperProvider() {
          super();
      }
  
      @Override
      public String name() {
          return "zookeeper";
      }
  
      @Override
      public Class module() {
          return ClusterModule.class;
      }
  
      @Override
      public ConfigCreator newConfigCreator() {
          return new ConfigCreator<ClusterModuleZookeeperConfig>() {
              @Override
              public Class type() {
                  return ClusterModuleZookeeperConfig.class;
              }
  
              @Override
              public void onInitialized(final ClusterModuleZookeeperConfig initialized) {
                  config = initialized;
              }
          };
      }
  
      @Override
      public void prepare() throws ServiceNotProvidedException, ModuleStartException {
          RetryPolicy retryPolicy = new ExponentialBackoffRetry(config.getBaseSleepTimeMs(), config.getMaxRetries());
  
          CuratorFrameworkFactory.Builder builder = CuratorFrameworkFactory.builder()
                                                                           .retryPolicy(retryPolicy)
                                                                           .connectString(config.getHostPort());
  
          if (config.isEnableACL()) {
              String authInfo = config.getExpression();
              if ("digest".equals(config.getSchema())) {
                  try {
                      authInfo = DigestAuthenticationProvider.generateDigest(authInfo);
                  } catch (NoSuchAlgorithmException e) {
                      throw new ModuleStartException(e.getMessage(), e);
                  }
              } else {
                  throw new ModuleStartException("Support digest schema only.");
              }
              final List<ACL> acls = Lists.newArrayList();
              acls.add(new ACL(ZooDefs.Perms.ALL, new Id(config.getSchema(), authInfo)));
              acls.add(new ACL(ZooDefs.Perms.READ, ZooDefs.Ids.ANYONE_ID_UNSAFE));
  
              ACLProvider provider = new ACLProvider() {
                  @Override
                  public List<ACL> getDefaultAcl() {
                      return acls;
                  }
  
                  @Override
                  public List<ACL> getAclForPath(String s) {
                      return acls;
                  }
              };
              builder.aclProvider(provider);
              builder.authorization(config.getSchema(), config.getExpression().getBytes(StandardCharsets.UTF_8));
          }
          client = builder.build();
  
          String path = BASE_PATH + (StringUtil.isEmpty(config.getNamespace()) ? "" : "/" + config.getNamespace());
  
          serviceDiscovery = ServiceDiscoveryBuilder.builder(RemoteInstance.class)
                                                    .client(client)
                                                    .basePath(path)
                                                    .watchInstances(true)
                                                    .serializer(new SWInstanceSerializer())
                                                    .build();
          try {
              client.start();
              client.blockUntilConnected();
              serviceDiscovery.start();
              coordinator = new ZookeeperCoordinator(getManager(), config, serviceDiscovery);
          } catch (Exception e) {
              LOGGER.error(e.getMessage(), e);
              throw new ModuleStartException(e.getMessage(), e);
          }
  
          this.registerServiceImplementation(ClusterRegister.class, coordinator);
          this.registerServiceImplementation(ClusterNodesQuery.class, coordinator);
          this.registerServiceImplementation(ClusterCoordinator.class, coordinator);
      }
  
      @Override
      public void start() {
      }
  
      @Override
      public void notifyAfterCompleted() {
      }
  
      @Override
      public String[] requiredModules() {
          return new String[]{CoreModule.NAME};
      }
  }
  