content: /*
   * 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.atlas.authorize;
  
  import org.apache.atlas.ApplicationProperties;
  import org.apache.atlas.AtlasException;
  import org.apache.atlas.authorize.simple.AtlasSimpleAuthorizer;
  import org.apache.commons.configuration.Configuration;
  import org.apache.commons.lang.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class AtlasAuthorizerFactory {
      private static final Logger LOG = LoggerFactory.getLogger(AtlasAuthorizerFactory.class);
  
      private static final String NONE_AUTHORIZER   = AtlasNoneAuthorizer.class.getName();
      private static final String SIMPLE_AUTHORIZER = AtlasSimpleAuthorizer.class.getName();
      private static final String RANGER_AUTHORIZER = "org.apache.ranger.authorization.atlas.authorizer.RangerAtlasAuthorizer";
  
      private static volatile AtlasAuthorizer instance;
  
      private AtlasAuthorizerFactory() {
          // to block instantiation
      }
  
      public static AtlasAuthorizer getAtlasAuthorizer() throws AtlasAuthorizationException {
          AtlasAuthorizer ret = AtlasAuthorizerFactory.instance;
  
          if (ret == null) {
              synchronized (AtlasAuthorizerFactory.class) {
                  ret = AtlasAuthorizerFactory.instance;
  
                  if (ret == null) {
                      Configuration configuration = null;
  
                      try {
                          configuration = ApplicationProperties.get();
                      } catch (AtlasException e) {
                          LOG.error("Exception while fetching configuration", e);
                      }
  
                      String authorizerClass = configuration != null ? configuration.getString("atlas.authorizer.impl") : "SIMPLE";
  
                      if (StringUtils.isNotEmpty(authorizerClass)) {
                          if (StringUtils.equalsIgnoreCase(authorizerClass, "SIMPLE")) {
                              authorizerClass = SIMPLE_AUTHORIZER;
                          } else if (StringUtils.equalsIgnoreCase(authorizerClass, "RANGER")) {
                              authorizerClass = RANGER_AUTHORIZER;
                          } else if (StringUtils.equalsIgnoreCase(authorizerClass, "NONE")) {
                              authorizerClass = NONE_AUTHORIZER;
                          }
                      } else {
                          authorizerClass = SIMPLE_AUTHORIZER;
                      }
  
                      LOG.info("Initializing Authorizer {}", authorizerClass);
  
                      try {
                          Class<?> authorizerMetaObject = Class.forName(authorizerClass);
  
                          ret = (AtlasAuthorizer) authorizerMetaObject.newInstance();
  
                          ret.init();
  
                          AtlasAuthorizerFactory.instance = ret;
                      } catch (Exception e) {
                          LOG.error("Error while creating authorizer of type {}", authorizerClass, e);
  
                          throw new AtlasAuthorizationException("Error while creating authorizer of type '" + authorizerClass + "'", e);
                      }
                  }
              }
          }
  
          return ret;
      }
  }
  