Loader.java

/*
 * Copyright 2015 Cloudera.
 *
 * Licensed 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.kitesdk.data.spi.s3;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Map;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.kitesdk.data.DatasetIOException;
import org.kitesdk.data.DatasetOperationException;
import org.kitesdk.data.spi.DatasetRepository;
import org.kitesdk.data.spi.DefaultConfiguration;
import org.kitesdk.data.spi.Loadable;
import org.kitesdk.data.spi.OptionBuilder;
import org.kitesdk.data.spi.Registration;
import org.kitesdk.data.spi.URIPattern;
import org.kitesdk.data.spi.filesystem.FileSystemDatasetRepository;

/**
 * A Loader implementation to register URIs for S3.
 */
public class Loader implements Loadable {

  private static final int UNSPECIFIED_PORT = -1;

  /**
   * This class builds configured instances of
   * {@code FileSystemDatasetRepository} from a Map of options. This is for the
   * URI system.
   */
  private static class URIBuilder implements OptionBuilder<DatasetRepository> {

    @Override
    public DatasetRepository getFromOptions(Map<String, String> match) {
      String path = match.get("path");
      final Path root = (path == null || path.isEmpty()) ?
          new Path("/") : new Path("/", path);

      Configuration conf = DefaultConfiguration.get();
      FileSystem fs;
      try {
        fs = FileSystem.get(fileSystemURI(match), conf);
      } catch (IOException e) {
        // "Incomplete HDFS URI, no host" => add a helpful suggestion
        if (e.getMessage().startsWith("Incomplete")) {
          throw new DatasetIOException("Could not get a FileSystem: " +
              "make sure the credentials for " + match.get(URIPattern.SCHEME) +
              " URIs are configured.", e);
        }
        throw new DatasetIOException("Could not get a FileSystem", e);
      }
      return new FileSystemDatasetRepository.Builder()
          .configuration(new Configuration(conf)) // make a modifiable copy
          .rootDirectory(fs.makeQualified(root))
          .build();
    }
  }

  @Override
  public void load() {
    try {
      // load hdfs-site.xml by loading HdfsConfiguration
      FileSystem.getLocal(DefaultConfiguration.get());
    } catch (IOException e) {
      throw new DatasetIOException("Cannot load default config", e);
    }

    OptionBuilder<DatasetRepository> builder = new URIBuilder();

    // username and secret are the same; host is the bucket
    Registration.register(
        new URIPattern("s3n:/*path"),
        new URIPattern("s3n:/*path/:namespace/:dataset"),
        builder);
    Registration.register(
        new URIPattern("s3a:/*path"),
        new URIPattern("s3a:/*path/:namespace/:dataset"),
        builder);
  }

  private static URI fileSystemURI(Map<String, String> match) {
    final String userInfo;
    if (match.containsKey(URIPattern.USERNAME)) {
      if (match.containsKey(URIPattern.PASSWORD)) {
        userInfo = match.get(URIPattern.USERNAME) + ":" +
            match.get(URIPattern.PASSWORD);
      } else {
        userInfo = match.get(URIPattern.USERNAME);
      }
    } else {
      userInfo = null;
    }
    try {
      int port = UNSPECIFIED_PORT;
      if (match.containsKey(URIPattern.PORT)) {
        try {
          port = Integer.parseInt(match.get(URIPattern.PORT));
        } catch (NumberFormatException e) {
          port = UNSPECIFIED_PORT;
        }
      }
      return new URI(match.get(URIPattern.SCHEME), userInfo,
          match.get(URIPattern.HOST), port, "/", null, null);
    } catch (URISyntaxException ex) {
      throw new DatasetOperationException("[BUG] Could not build FS URI", ex);
    }
  }
}