org.apache.hadoop.mapred

Class SshFenceByTcpPort

java.lang.Object

org.apache.hadoop.conf.Configured

org.apache.hadoop.mapred.SshFenceByTcpPort

All Implemented Interfaces:

org.apache.hadoop.conf.Configurable, org.apache.hadoop.ha.FenceMethod

public class SshFenceByTcpPort
extends org.apache.hadoop.conf.Configured
implements org.apache.hadoop.ha.FenceMethod

NOTE: This is a copy of org.apache.hadoop.ha.SshFenceByTcpPort that uses MR-specific configuration options (since the original is hardcoded to HDFS configuration properties so there is no way to run MR and HDFS fencing using a single configuration file). This fencing implementation sshes to the target node and uses fuser to kill the process listening on the service's TCP port. This is more accurate than using "jps" since it doesn't require parsing, and will work even if there are multiple service processes running on the same machine.

It returns a successful status code if:

• fuser indicates it successfully killed a process, or
• nc -z indicates that nothing is listening on the target port

This fencing mechanism is configured as following in the fencing method list: sshfence([[username][:ssh-port]]) where the optional argument specifies the username and port to use with ssh.

In order to achieve passwordless SSH, the operator must also configure mapred.ha.fencing.ssh.private-key-files to point to an SSH key that has passphrase-less access to the given username and host.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SshFenceByTcpPort.Args Container for the parsed arg line for this fencing method.

Field Summary

Fields

Modifier and Type	Field and Description
static String	CONF_CONNECT_TIMEOUT_KEY
static String	CONF_IDENTITIES_KEY
static org.apache.commons.logging.Log	LOG

Constructor Summary

Constructors

Constructor and Description
SshFenceByTcpPort()

Method Summary

Methods

Modifier and Type	Method and Description
void	checkArgs(String argStr) Verify that the argument, if given, in the conf is parseable.
boolean	tryFence(org.apache.hadoop.ha.HAServiceTarget target, String argsStr)

Methods inherited from class org.apache.hadoop.conf.Configured

getConf, setConf

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG

public static final org.apache.commons.logging.Log LOG

CONF_CONNECT_TIMEOUT_KEY

public static final String CONF_CONNECT_TIMEOUT_KEY

See Also:

Constant Field Values

CONF_IDENTITIES_KEY

public static final String CONF_IDENTITIES_KEY

See Also:

Constant Field Values

Constructor Detail

SshFenceByTcpPort

public SshFenceByTcpPort()

Method Detail

checkArgs

public void checkArgs(String argStr)
               throws org.apache.hadoop.ha.BadFencingConfigurationException

Verify that the argument, if given, in the conf is parseable.

Specified by:

checkArgs in interface org.apache.hadoop.ha.FenceMethod

Throws:

org.apache.hadoop.ha.BadFencingConfigurationException

tryFence

public boolean tryFence(org.apache.hadoop.ha.HAServiceTarget target,
               String argsStr)
                 throws org.apache.hadoop.ha.BadFencingConfigurationException

Specified by:

tryFence in interface org.apache.hadoop.ha.FenceMethod

Throws:

org.apache.hadoop.ha.BadFencingConfigurationException