org.apache.hadoop.util.SSHRemoteExecution Maven / Gradle / Ivy
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/**
* 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.hadoop.util;
import com.jcraft.jsch.*;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Properties;
/**
* Remote Execution of commands on a remote machine.
*/
public class SSHRemoteExecution implements RemoteExecution {
static final Log LOG = LogFactory.getLog(SSHRemoteExecution.class);
static final int SSH_PORT = 22;
static final String DEFAULT_IDENTITY="id_dsa";
static final String DEFAULT_KNOWNHOSTS="known_hosts";
static final String FS = System.getProperty("file.separator");
static final String LS = System.getProperty("line.separator");
private int exitCode;
private StringBuffer output;
private String commandString;
final StringBuffer errorMessage = new StringBuffer();
public SSHRemoteExecution() throws Exception {
}
protected String getHomeDir() {
String currentUser=System.getProperty("user.name");
String userHome=System.getProperty("user.home");
return userHome.substring(0, userHome.indexOf(currentUser)-1);
}
/**
* Execute command at remote host under given user
* @param remoteHostName remote host name
* @param user is the name of the user to be login under;
* current user will be used if this is set to null
* @param command to be executed remotely
* @param identityFile is the name of alternative identity file; default
* is ~user/.ssh/id_dsa
* @param portNumber remote SSH daemon port number, default is 22
* @throws Exception in case of errors
*/
public void executeCommand (String remoteHostName, String user,
String command, String identityFile, int portNumber) throws Exception {
commandString = command;
String sessionUser = System.getProperty("user.name");
String userHome=System.getProperty("user.home");
if (user != null) {
sessionUser = user;
userHome = getHomeDir() + FS + user;
}
String dotSSHDir = userHome + FS + ".ssh";
String sessionIdentity = dotSSHDir + FS + DEFAULT_IDENTITY;
if (identityFile != null) {
sessionIdentity = identityFile;
}
JSch jsch = new JSch();
Session session = jsch.getSession(sessionUser, remoteHostName, portNumber);
jsch.setKnownHosts(dotSSHDir + FS + DEFAULT_KNOWNHOSTS);
jsch.addIdentity(sessionIdentity);
Properties config = new Properties();
config.put("StrictHostKeyChecking", "no");
session.setConfig(config);
session.connect(30000); // making a connection with timeout.
Channel channel=session.openChannel("exec");
((ChannelExec)channel).setCommand(command);
channel.setInputStream(null);
final BufferedReader errReader =
new BufferedReader(
new InputStreamReader(((ChannelExec)channel).getErrStream()));
BufferedReader inReader =
new BufferedReader(new InputStreamReader(channel.getInputStream()));
channel.connect();
Thread errorThread = new Thread() {
@Override
public void run() {
try {
String line = errReader.readLine();
while((line != null) && !isInterrupted()) {
errorMessage.append(line);
errorMessage.append(LS);
line = errReader.readLine();
}
} catch(IOException ioe) {
LOG.warn("Error reading the error stream", ioe);
}
}
};
try {
errorThread.start();
} catch (IllegalStateException e) {
LOG.debug(e);
}
try {
parseExecResult(inReader);
String line = inReader.readLine();
while (line != null) {
line = inReader.readLine();
}
if(channel.isClosed()) {
exitCode = channel.getExitStatus();
LOG.debug("exit-status: " + exitCode);
}
try {
// make sure that the error thread exits
errorThread.join();
} catch (InterruptedException ie) {
LOG.warn("Interrupted while reading the error stream", ie);
}
} catch (Exception ie) {
throw new IOException(ie.toString());
}
finally {
try {
inReader.close();
} catch (IOException ioe) {
LOG.warn("Error while closing the input stream", ioe);
}
try {
errReader.close();
} catch (IOException ioe) {
LOG.warn("Error while closing the error stream", ioe);
}
channel.disconnect();
session.disconnect();
}
}
/**
* Execute command at remote host under given username
* Default identity is ~/.ssh/id_dsa key will be used
* Default known_hosts file is ~/.ssh/known_hosts will be used
* @param remoteHostName remote host name
* @param user is the name of the user to be login under;
* if equals to null then current user name will be used
* @param command to be executed remotely
*/
@Override
public void executeCommand (String remoteHostName, String user,
String command) throws Exception {
executeCommand(remoteHostName, user, command, null, SSH_PORT);
}
@Override
public int getExitCode() {
return exitCode;
}
protected void parseExecResult(BufferedReader lines) throws IOException {
output = new StringBuffer();
char[] buf = new char[512];
int nRead;
while ( (nRead = lines.read(buf, 0, buf.length)) > 0 ) {
output.append(buf, 0, nRead);
}
}
/** Get the output of the ssh command.*/
@Override
public String getOutput() {
return (output == null) ? "" : output.toString();
}
/** Get the String representation of ssh command */
@Override
public String getCommandString() {
return commandString;
}
}