core/src/main/java/org/apache/accumulo/core/conf/SiteConfiguration.java

/*
 * 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.accumulo.core.conf;

import java.io.IOException;
import java.util.Map;
import java.util.Map.Entry;

import org.apache.accumulo.core.util.CachedConfiguration;
import org.apache.hadoop.conf.Configuration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Predicate;

/**
 * An {@link AccumuloConfiguration} which loads properties from an XML file, usually accumulo-site.xml. This implementation supports defaulting undefined
 * property values to a parent configuration's definitions.
 * <p>
 * The system property "org.apache.accumulo.config.file" can be used to specify the location of the XML configuration file on the classpath. If the system
 * property is not defined, it defaults to "accumulo-site.xml".
 * <p>
 * This class is a singleton.
 * <p>
 * <b>Note</b>: Client code should not use this class, and it may be deprecated in the future.
 */
public class SiteConfiguration extends AccumuloConfiguration {
  private static final Logger log = LoggerFactory.getLogger(SiteConfiguration.class);

  private AccumuloConfiguration parent = null;
  private static SiteConfiguration instance = null;

  private static Configuration xmlConfig;

  /**
   * Not for consumers. Call {@link SiteConfiguration#getInstance(AccumuloConfiguration)} instead
   */
  SiteConfiguration(AccumuloConfiguration parent) {
    this.parent = parent;
  }

  /**
   * Gets an instance of this class. A new instance is only created on the first call, and so the parent configuration cannot be changed later.
   *
   * @param parent
   *          parent (default) configuration
   * @throws RuntimeException
   *           if the configuration is invalid
   */
  synchronized public static SiteConfiguration getInstance(AccumuloConfiguration parent) {
    if (instance == null) {
      instance = new SiteConfiguration(parent);
      ConfigSanityCheck.validate(instance);
    }
    return instance;
  }

  synchronized public static SiteConfiguration getInstance() {
    return getInstance(DefaultConfiguration.getInstance());
  }

  synchronized private static Configuration getXmlConfig() {
    String configFile = System.getProperty("org.apache.accumulo.config.file", "accumulo-site.xml");
    if (xmlConfig == null) {
      xmlConfig = new Configuration(false);

      if (SiteConfiguration.class.getClassLoader().getResource(configFile) == null)
        log.warn(configFile + " not found on classpath", new Throwable());
      else
        xmlConfig.addResource(configFile);
    }
    return xmlConfig;
  }

  @Override
  public String get(Property property) {
    String key = property.getKey();

    // If the property is sensitive, see if CredentialProvider was configured.
    if (property.isSensitive()) {
      Configuration hadoopConf = getHadoopConfiguration();
      if (null != hadoopConf) {
        // Try to find the sensitive value from the CredentialProvider
        try {
          char[] value = CredentialProviderFactoryShim.getValueFromCredentialProvider(hadoopConf, key);
          if (null != value) {
            return new String(value);
          }
        } catch (IOException e) {
          log.warn("Failed to extract sensitive property (" + key + ") from Hadoop CredentialProvider, falling back to accumulo-site.xml", e);
        }
      }
    }

    String value = getXmlConfig().get(key);

    if (value == null || !property.getType().isValidFormat(value)) {
      if (value != null)
        log.error("Using default value for " + key + " due to improperly formatted " + property.getType() + ": " + value);
      value = parent.get(property);
    }
    return value;
  }

  @Override
  public void getProperties(Map<String,String> props, Predicate<String> filter) {
    parent.getProperties(props, filter);

    for (Entry<String,String> entry : getXmlConfig())
      if (filter.apply(entry.getKey()))
        props.put(entry.getKey(), entry.getValue());

    // CredentialProvider should take precedence over site
    Configuration hadoopConf = getHadoopConfiguration();
    if (null != hadoopConf) {
      try {
        for (String key : CredentialProviderFactoryShim.getKeys(hadoopConf)) {
          if (!Property.isValidPropertyKey(key) || !Property.isSensitive(key)) {
            continue;
          }

          if (filter.apply(key)) {
            char[] value = CredentialProviderFactoryShim.getValueFromCredentialProvider(hadoopConf, key);
            if (null != value) {
              props.put(key, new String(value));
            }
          }
        }
      } catch (IOException e) {
        log.warn("Failed to extract sensitive properties from Hadoop CredentialProvider, falling back to accumulo-site.xml", e);
      }
    }
  }

  protected Configuration getHadoopConfiguration() {
    String credProviderPathsKey = Property.GENERAL_SECURITY_CREDENTIAL_PROVIDER_PATHS.getKey();
    String credProviderPathsValue = getXmlConfig().get(credProviderPathsKey);

    if (null != credProviderPathsValue) {
      // We have configuration for a CredentialProvider
      // Try to pull the sensitive password from there
      Configuration conf = new Configuration(CachedConfiguration.getInstance());
      conf.set(CredentialProviderFactoryShim.CREDENTIAL_PROVIDER_PATH, credProviderPathsValue);
      return conf;
    }

    return null;
  }

  /**
   * Clears the configuration properties in this configuration (but not the parent). This method supports testing and should not be called.
   */
  synchronized public static void clearInstance() {
    instance = null;
  }

  /**
   * Sets a property. This method supports testing and should not be called.
   *
   * @param property
   *          property to set
   * @param value
   *          property value
   */
  public void set(Property property, String value) {
    set(property.getKey(), value);
  }

  /**
   * Sets a property. This method supports testing and should not be called.
   *
   * @param key
   *          key of property to set
   * @param value
   *          property value
   */
  public void set(String key, String value) {
    getXmlConfig().set(key, value);
  }
}