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.web.listeners;
  
  import org.apache.atlas.ApplicationProperties;
  import org.apache.atlas.AtlasException;
  import org.apache.atlas.security.SecurityProperties;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.security.SecurityUtil;
  import org.apache.hadoop.security.UserGroupInformation;
  import org.apache.hadoop.util.Shell;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  import java.net.InetAddress;
  import java.net.UnknownHostException;
  
  /**
   * A class capable of performing a simple or kerberos login.
   */
  public class LoginProcessor {
      private static final Logger LOG = LoggerFactory.getLogger(LoginProcessor.class);
  
      public static final  String ATLAS_AUTHENTICATION_PREFIX    = "atlas.authentication.";
      public static final  String AUTHENTICATION_KERBEROS_METHOD = ATLAS_AUTHENTICATION_PREFIX + "method.kerberos";
      public static final  String AUTHENTICATION_PRINCIPAL       = ATLAS_AUTHENTICATION_PREFIX + "principal";
      public static final  String AUTHENTICATION_KEYTAB          = ATLAS_AUTHENTICATION_PREFIX + "keytab";
  
      /**
       * Perform a SIMPLE login based on established OS identity or a kerberos based login using the configured
       * principal and keytab (via atlas-application.properties).
       */
      public void login() {
          // first, let's see if we're running in a hadoop cluster and have the env configured
          boolean                                        isHadoopCluster = isHadoopCluster();
          Configuration                                  hadoopConfig    = isHadoopCluster ? getHadoopConfiguration() : new Configuration(false);
          org.apache.commons.configuration.Configuration configuration   = getApplicationConfiguration();
  
          if (!isHadoopCluster) {
              // need to read the configured authentication choice and create the UGI configuration
              setupHadoopConfiguration(hadoopConfig, configuration);
          }
  
          doServiceLogin(hadoopConfig, configuration);
      }
  
      protected void doServiceLogin(Configuration hadoopConfig, org.apache.commons.configuration.Configuration configuration) {
          UserGroupInformation.setConfiguration(hadoopConfig);
  
          UserGroupInformation.AuthenticationMethod authenticationMethod = SecurityUtil.getAuthenticationMethod(hadoopConfig);
  
          try {
              if (authenticationMethod == UserGroupInformation.AuthenticationMethod.SIMPLE) {
                  UserGroupInformation.loginUserFromSubject(null);
              } else if (authenticationMethod == UserGroupInformation.AuthenticationMethod.KERBEROS) {
                  String bindAddress = getHostname(configuration);
  
                  UserGroupInformation.loginUserFromKeytab(getServerPrincipal(configuration.getString(AUTHENTICATION_PRINCIPAL), bindAddress), configuration.getString(AUTHENTICATION_KEYTAB));
              }
              LOG.info("Logged in user {}", UserGroupInformation.getLoginUser());
          } catch (IOException e) {
              throw new IllegalStateException(String.format("Unable to perform %s login.", authenticationMethod), e);
          }
      }
  
      protected void setupHadoopConfiguration(Configuration hadoopConfig, org.apache.commons.configuration.Configuration configuration) {
          String authMethod           = "";
          String kerberosAuthNEnabled = configuration != null ? configuration.getString(AUTHENTICATION_KERBEROS_METHOD) : null;
  
          // getString may return null, and would like to log the nature of the default setting
          if (kerberosAuthNEnabled == null || kerberosAuthNEnabled.equalsIgnoreCase("false")) {
              LOG.info("No authentication method configured.  Defaulting to simple authentication");
  
              authMethod = "simple";
          } else if (kerberosAuthNEnabled.equalsIgnoreCase("true")) {
              authMethod = "kerberos";
          }
  
          SecurityUtil.setAuthenticationMethod(UserGroupInformation.AuthenticationMethod.valueOf(authMethod.toUpperCase()), hadoopConfig);
      }
  
      /**
       * Returns a Hadoop configuration instance.
       *
       * @return the configuration.
       */
      protected Configuration getHadoopConfiguration() {
          return new Configuration();
      }
  
      /**
       * Returns the metadata application configuration.
       *
       * @return the metadata configuration.
       */
      protected org.apache.commons.configuration.Configuration getApplicationConfiguration() {
          try {
              return ApplicationProperties.get();
          } catch (AtlasException e) {
              LOG.warn("Error reading application configuration", e);
          }
  
          return null;
      }
  
      /**
       * Uses a hadoop shell to discern whether a hadoop cluster is available/configured.
       *
       * @return true if a hadoop cluster is detected.
       */
      protected boolean isHadoopCluster() {
          boolean isHadoopCluster = false;
  
          try {
              isHadoopCluster = Shell.getHadoopHome() != null;
          } catch (IOException e) {
              // ignore - false is default setting
          }
  
          return isHadoopCluster;
      }
  
      private String getHostname(org.apache.commons.configuration.Configuration configuration) {
          String bindAddress = configuration.getString(SecurityProperties.BIND_ADDRESS);
  
          if (bindAddress == null) {
              LOG.info("No host name configured.  Defaulting to local host name.");
  
              try {
                  bindAddress = InetAddress.getLocalHost().getHostName();
              } catch (UnknownHostException e) {
                  throw new IllegalStateException(e);
              }
          }
  
          return bindAddress;
      }
  
      /**
       * Return a server (service) principal.  The token "_HOST" in the principal will be replaced with the local host
       * name (e.g. dgi/_HOST will be changed to dgi/localHostName)
       *
       * @param principal the input principal containing an option "_HOST" token
       * @return the service principal.
       * @throws IOException
       */
      private String getServerPrincipal(String principal, String host) throws IOException {
          return SecurityUtil.getServerPrincipal(principal, host);
      }
  }
  