Add initial implementaion of zookeeper-based discovery service.

plugins/zookeeper/build.gradle

@@ -0,0 +1,131 @@
+dependsOn(':elasticsearch')
+
+apply plugin: 'java'
+apply plugin: 'maven'
+
+archivesBaseName = "elasticsearch-zookeeper"
+
+explodedDistDir = new File(distsDir, 'exploded')
+
+configurations.compile.transitive = true
+configurations.testCompile.transitive = true
+
+// no need to use the resource dir
+sourceSets.main.resources.srcDirs 'src/main/java'
+sourceSets.test.resources.srcDirs 'src/test/java'
+
+// add the source files to the dist jar
+//jar {
+//    from sourceSets.main.allJava
+//}
+
+configurations {
+    dists
+    distLib {
+        visible = false
+    }
+}
+
+dependencies {
+    compile project(':elasticsearch')
+    compile("org.apache.zookeeper:zookeeper:3.3.3") { transitive = false }
+
+    distLib("org.apache.zookeeper:zookeeper:3.3.3") { transitive = false }
+}
+
+task explodedDist(dependsOn: [jar], description: 'Builds the plugin zip file') << {
+    [explodedDistDir]*.mkdirs()
+
+    copy {
+        from configurations.distLib
+        into explodedDistDir
+    }
+
+    // remove elasticsearch files (compile above adds the elasticsearch one)
+    ant.delete { fileset(dir: explodedDistDir, includes: "elasticsearch-*.jar") }
+
+    copy {
+        from libsDir
+        into explodedDistDir
+    }
+
+    ant.delete { fileset(dir: explodedDistDir, includes: "elasticsearch-*-javadoc.jar") }
+    ant.delete { fileset(dir: explodedDistDir, includes: "elasticsearch-*-sources.jar") }
+}
+
+task zip(type: Zip, dependsOn: ['explodedDist']) {
+    from(explodedDistDir) {
+    }
+}
+
+task release(dependsOn: [zip]) << {
+    ant.delete(dir: explodedDistDir)
+    copy {
+        from distsDir
+        into(new File(rootProject.distsDir, "plugins"))
+    }
+}
+
+configurations {
+    deployerJars
+}
+
+dependencies {
+    deployerJars "org.apache.maven.wagon:wagon-http:1.0-beta-2"
+}
+
+task sourcesJar(type: Jar, dependsOn: classes) {
+    classifier = 'sources'
+    from sourceSets.main.allSource
+}
+
+task javadocJar(type: Jar, dependsOn: javadoc) {
+    classifier = 'javadoc'
+    from javadoc.destinationDir
+}
+
+jar {
+//    from sourceSets.main.allJava
+    manifest {
+        attributes("Implementation-Title": "ElasticSearch", "Implementation-Version": rootProject.version, "Implementation-Date": buildTimeStr)
+    }
+}
+
+artifacts {
+    archives sourcesJar
+    archives javadocJar
+}
+
+uploadArchives {
+    repositories.mavenDeployer {
+        configuration = configurations.deployerJars
+        repository(url: rootProject.mavenRepoUrl) {
+            authentication(userName: rootProject.mavenRepoUser, password: rootProject.mavenRepoPass)
+        }
+        snapshotRepository(url: rootProject.mavenSnapshotRepoUrl) {
+            authentication(userName: rootProject.mavenRepoUser, password: rootProject.mavenRepoPass)
+        }
+
+        pom.project {
+            inceptionYear '2011'
+            name 'elasticsearch-plugins-zookeeper'
+            description 'ZooKeeper Plugin for ElasticSearch'
+            licenses {
+                license {
+                    name 'The Apache Software License, Version 2.0'
+                    url 'http://www.apache.org/licenses/LICENSE-2.0.txt'
+                    distribution 'repo'
+                }
+            }
+            scm {
+                connection 'git://github.com/elasticsearch/elasticsearch.git'
+                developerConnection 'git@github.com:elasticsearch/elasticsearch.git'
+                url 'http://github.com/elasticsearch/elasticsearch'
+            }
+        }
+
+        pom.whenConfigured {pom ->
+            pom.dependencies = pom.dependencies.findAll {dep -> dep.scope != 'test' } // removes the test scoped ones
+        }
+    }
+}

plugins/zookeeper/src/main/java/es-plugin.properties

@@ -0,0 +1 @@
+plugin=org.elasticsearch.plugin.zookeeper.ZooKeeperPlugin

plugins/zookeeper/src/main/java/org/elasticsearch/common/settings/zookeeper/ZooKeeperSettingsLoader.java

@@ -0,0 +1,85 @@
+/*
+ * Licensed to Elastic Search and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Elastic Search 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.elasticsearch.common.settings.zookeeper;
+
+import org.apache.zookeeper.KeeperException;
+import org.apache.zookeeper.ZooKeeper;
+import org.elasticsearch.ElasticSearchException;
+import org.elasticsearch.cluster.ClusterName;
+import org.elasticsearch.common.settings.ImmutableSettings;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.settings.loader.SettingsLoader;
+import org.elasticsearch.common.settings.loader.SettingsLoaderFactory;
+import org.elasticsearch.zookeeper.ZooKeeperEnvironment;
+import org.elasticsearch.zookeeper.ZooKeeperFactory;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * @author imotov
+ */
+public final class ZooKeeperSettingsLoader {
+
+    private ZooKeeperSettingsLoader() {
+
+    }
+
+    public static Settings loadZooKeeperSettings(Settings settings) {
+        ZooKeeperFactory zooKeeperFactory = new ZooKeeperFactory(settings);
+
+        ClusterName clusterName = ClusterName.clusterNameFromSettings(settings);
+
+        ZooKeeperEnvironment zooKeeperEnvironment = new ZooKeeperEnvironment(settings, clusterName);
+
+        ZooKeeper zooKeeper = zooKeeperFactory.newZooKeeper();
+        try {
+            return ImmutableSettings.settingsBuilder()
+                    .put(loadSettings(zooKeeper, zooKeeperEnvironment.globalSettingsNodePath()))
+                    .put(loadSettings(zooKeeper, zooKeeperEnvironment.clusterSettingsNodePath()))
+                    .build();
+        } catch (InterruptedException e) {
+            // Ignore
+        } catch (KeeperException e) {
+            throw new ElasticSearchException("Cannot load settings ", e);
+        } finally {
+            try {
+                zooKeeper.close();
+            } catch (InterruptedException ex) {
+                // Ignore
+            }
+        }
+        return ImmutableSettings.Builder.EMPTY_SETTINGS;
+    }
+
+    private static Map<String, String> loadSettings(ZooKeeper zooKeeper, String path) throws InterruptedException, KeeperException {
+        try {
+            byte[] settingsBytes = zooKeeper.getData(path, null, null);
+            SettingsLoader loader = SettingsLoaderFactory.loaderFromSource(new String(settingsBytes));
+            return loader.load(settingsBytes);
+        } catch (KeeperException.NoNodeException e) {
+            return Collections.emptyMap();
+        } catch (IOException ex) {
+            throw new ElasticSearchException("Cannot load settings ", ex);
+        }
+    }
+}