apis/byon/src/main/java/org/jclouds/byon/functions/NodesFromYamlStream.java

/**
 * Licensed to jclouds, Inc. (jclouds) under one or more
 * contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  jclouds 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.jclouds.byon.functions;

import static com.google.common.base.Preconditions.checkState;

import java.io.InputStream;
import java.util.List;
import java.util.Map;

import javax.inject.Singleton;

import org.jclouds.byon.Node;
import org.jclouds.byon.domain.YamlNode;
import org.yaml.snakeyaml.Loader;
import org.yaml.snakeyaml.TypeDescription;
import org.yaml.snakeyaml.Yaml;
import org.yaml.snakeyaml.constructor.Constructor;

import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.Iterables;
import com.google.common.collect.Maps;

/**
 * Parses the following syntax.
 * 
 * <pre>
 * nodes:
 *     - id: cluster-1:
 *       name: cluster-1
 *       description: xyz
 *       hostname: cluster-1.mydomain.com
 *       location_id: virginia
 *       os_arch: x86
 *       os_family: linux
 *       os_description: redhat
 *       os_version: 5.3
 *       group: hadoop
 *       tags:
 *           - vanilla
 *       username: kelvin
 *       credential: password_or_rsa
 *         or
 *       credential_url: password_or_rsa_file ex. resource:///id_rsa will get the classpath /id_rsa; file://path/to/id_rsa
 *       sudo_password: password
 * </pre>
 * 
 * @author Kelvin Kakugawa
 * @author Adrian Cole
 */
@Singleton
public class NodesFromYamlStream implements Function<InputStream, LoadingCache<String, Node>> {

   /**
    * Type-safe config class for YAML
    * 
    */
   public static class Config {
      public List<YamlNode> nodes;
   }

   @Override
   public LoadingCache<String, Node> apply(InputStream source) {

      Constructor constructor = new Constructor(Config.class);

      TypeDescription nodeDesc = new TypeDescription(YamlNode.class);
      nodeDesc.putListPropertyType("tags", String.class);
      constructor.addTypeDescription(nodeDesc);

      TypeDescription configDesc = new TypeDescription(Config.class);
      configDesc.putListPropertyType("nodes", YamlNode.class);
      constructor.addTypeDescription(configDesc);
      // note that snakeyaml also throws nosuchmethod error when you use the
      // non-deprecated
      // constructor
      Yaml yaml = new Yaml(new Loader(constructor));
      Config config = (Config) yaml.load(source);
      checkState(config != null, "missing config: class");
      checkState(config.nodes != null, "missing nodes: collection");

      Map<String, Node> backingMap = Maps.uniqueIndex(Iterables.transform(config.nodes, YamlNode.toNode),
            new Function<Node, String>() {
               public String apply(Node node) {
                  return node.getId();
               }
            });
      LoadingCache<String, Node> cache = CacheBuilder.newBuilder().build(CacheLoader.from(Functions.forMap(backingMap)));
      for (String node : backingMap.keySet())
         cache.getUnchecked(node);
      return cache;
   }
}