/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.bootstrap;
import org.apache.lucene.util.IOUtils;
import org.elasticsearch.env.Environment;
import org.elasticsearch.plugins.Platforms;
import org.elasticsearch.plugins.PluginInfo;
import java.io.Closeable;
import java.io.IOException;
import java.nio.file.DirectoryStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* Spawns native plugin controller processes if present. Will only work prior to a system call
* filter being installed.
*/
final class Spawner implements Closeable {
/*
* References to the processes that have been spawned, so that we can destroy them.
*/
private final List<Process> processes = new ArrayList<>();
private AtomicBoolean spawned = new AtomicBoolean();
@Override
public void close() throws IOException {
IOUtils.close(() -> processes.stream().map(s -> (Closeable) s::destroy).iterator());
}
/**
* Spawns the native controllers for each plugin
*
* @param environment the node environment
* @throws IOException if an I/O error occurs reading the plugins or spawning a native process
*/
void spawnNativePluginControllers(final Environment environment) throws IOException {
if (!spawned.compareAndSet(false, true)) {
throw new IllegalStateException("native controllers already spawned");
}
final Path pluginsFile = environment.pluginsFile();
if (!Files.exists(pluginsFile)) {
throw new IllegalStateException("plugins directory [" + pluginsFile + "] not found");
}
/*
* For each plugin, attempt to spawn the controller daemon. Silently ignore any plugin that
* don't include a controller for the correct platform.
*/
try (DirectoryStream<Path> stream = Files.newDirectoryStream(pluginsFile)) {
for (final Path plugin : stream) {
final PluginInfo info = PluginInfo.readFromProperties(plugin);
final Path spawnPath = Platforms.nativeControllerPath(plugin);
if (!Files.isRegularFile(spawnPath)) {
continue;
}
if (!info.hasNativeController()) {
final String message = String.format(
Locale.ROOT,
"plugin [%s] does not have permission to fork native controller",
plugin.getFileName());
throw new IllegalArgumentException(message);
}
final Process process =
spawnNativePluginController(spawnPath, environment.tmpFile());
processes.add(process);
}
}
}
/**
* Attempt to spawn the controller daemon for a given plugin. The spawned process will remain
* connected to this JVM via its stdin, stdout, and stderr streams, but the references to these
* streams are not available to code outside this package.
*/
private Process spawnNativePluginController(
final Path spawnPath,
final Path tmpPath) throws IOException {
final ProcessBuilder pb = new ProcessBuilder(spawnPath.toString());
// the only environment variable passes on the path to the temporary directory
pb.environment().clear();
pb.environment().put("TMPDIR", tmpPath.toString());
// the output stream of the process object corresponds to the daemon's stdin
return pb.start();
}
/**
* The collection of processes representing spawned native controllers.
*
* @return the processes
*/
List<Process> getProcesses() {
return Collections.unmodifiableList(processes);
}
}