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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 java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Timer;
import java.util.TimerTask;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.service.AbstractService;
import org.apache.hadoop.util.Shell.ExitCodeException;
import org.apache.hadoop.util.Shell.ShellCommandExecutor;
import org.apache.hadoop.util.Shell;
import org.apache.hadoop.util.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
*
* The class which provides functionality of checking the health of the node
* using the configured node health script and reporting back to the service
* for which the health checker has been asked to report.
*/
public class NodeHealthScriptRunner extends AbstractService {
private static final Logger LOG =
LoggerFactory.getLogger(NodeHealthScriptRunner.class);
/** Absolute path to the health script. */
private String nodeHealthScript;
/** Delay after which node health script to be executed */
private long intervalTime;
/** Time after which the script should be timedout */
private long scriptTimeout;
/** Timer used to schedule node health monitoring script execution */
private Timer nodeHealthScriptScheduler;
/** ShellCommandExecutor used to execute monitoring script */
ShellCommandExecutor shexec = null;
/** Pattern used for searching in the output of the node health script */
static private final String ERROR_PATTERN = "ERROR";
/** Time out error message */
public static final String NODE_HEALTH_SCRIPT_TIMED_OUT_MSG = "Node health script timed out";
private boolean isHealthy;
private String healthReport;
private long lastReportedTime;
private TimerTask timer;
private enum HealthCheckerExitStatus {
SUCCESS,
TIMED_OUT,
FAILED_WITH_EXIT_CODE,
FAILED_WITH_EXCEPTION,
FAILED
}
/**
* Class which is used by the {@link Timer} class to periodically execute the
* node health script.
*
*/
private class NodeHealthMonitorExecutor extends TimerTask {
String exceptionStackTrace = "";
public NodeHealthMonitorExecutor(String[] args) {
ArrayList execScript = new ArrayList();
execScript.add(nodeHealthScript);
if (args != null) {
execScript.addAll(Arrays.asList(args));
}
shexec = new ShellCommandExecutor(execScript
.toArray(new String[execScript.size()]), null, null, scriptTimeout);
}
@Override
public void run() {
HealthCheckerExitStatus status = HealthCheckerExitStatus.SUCCESS;
try {
shexec.execute();
} catch (ExitCodeException e) {
// ignore the exit code of the script
status = HealthCheckerExitStatus.FAILED_WITH_EXIT_CODE;
// On Windows, we will not hit the Stream closed IOException
// thrown by stdout buffered reader for timeout event.
if (Shell.WINDOWS && shexec.isTimedOut()) {
status = HealthCheckerExitStatus.TIMED_OUT;
}
} catch (Exception e) {
LOG.warn("Caught exception : " + e.getMessage());
if (!shexec.isTimedOut()) {
status = HealthCheckerExitStatus.FAILED_WITH_EXCEPTION;
} else {
status = HealthCheckerExitStatus.TIMED_OUT;
}
exceptionStackTrace = StringUtils.stringifyException(e);
} finally {
if (status == HealthCheckerExitStatus.SUCCESS) {
if (hasErrors(shexec.getOutput())) {
status = HealthCheckerExitStatus.FAILED;
}
}
reportHealthStatus(status);
}
}
/**
* Method which is used to parse output from the node health monitor and
* send to the report address.
*
* The timed out script or script which causes IOException output is
* ignored.
*
* The node is marked unhealthy if
*
*
The node health script times out
*
The node health scripts output has a line which begins with ERROR
*
An exception is thrown while executing the script
*
* If the script throws {@link IOException} or {@link ExitCodeException} the
* output is ignored and node is left remaining healthy, as script might
* have syntax error.
*
* @param status
*/
void reportHealthStatus(HealthCheckerExitStatus status) {
long now = System.currentTimeMillis();
switch (status) {
case SUCCESS:
setHealthStatus(true, "", now);
break;
case TIMED_OUT:
setHealthStatus(false, NODE_HEALTH_SCRIPT_TIMED_OUT_MSG);
break;
case FAILED_WITH_EXCEPTION:
setHealthStatus(false, exceptionStackTrace);
break;
case FAILED_WITH_EXIT_CODE:
setHealthStatus(true, "", now);
break;
case FAILED:
setHealthStatus(false, shexec.getOutput());
break;
}
}
/**
* Method to check if the output string has line which begins with ERROR.
*
* @param output
* string
* @return true if output string has error pattern in it.
*/
private boolean hasErrors(String output) {
String[] splits = output.split("\n");
for (String split : splits) {
if (split.startsWith(ERROR_PATTERN)) {
return true;
}
}
return false;
}
}
public NodeHealthScriptRunner(String scriptName, long chkInterval, long timeout,
String[] scriptArgs) {
super(NodeHealthScriptRunner.class.getName());
this.lastReportedTime = System.currentTimeMillis();
this.isHealthy = true;
this.healthReport = "";
this.nodeHealthScript = scriptName;
this.intervalTime = chkInterval;
this.scriptTimeout = timeout;
this.timer = new NodeHealthMonitorExecutor(scriptArgs);
}
/*
* Method which initializes the values for the script path and interval time.
*/
@Override
protected void serviceInit(Configuration conf) throws Exception {
super.serviceInit(conf);
}
/**
* Method used to start the Node health monitoring.
*
*/
@Override
protected void serviceStart() throws Exception {
nodeHealthScriptScheduler = new Timer("NodeHealthMonitor-Timer", true);
// Start the timer task immediately and
// then periodically at interval time.
nodeHealthScriptScheduler.scheduleAtFixedRate(timer, 0, intervalTime);
super.serviceStart();
}
/**
* Method used to terminate the node health monitoring service.
*
*/
@Override
protected void serviceStop() {
if (nodeHealthScriptScheduler != null) {
nodeHealthScriptScheduler.cancel();
}
if (shexec != null) {
Process p = shexec.getProcess();
if (p != null) {
p.destroy();
}
}
}
/**
* Gets the if the node is healthy or not
*
* @return true if node is healthy
*/
public boolean isHealthy() {
return isHealthy;
}
/**
* Sets if the node is healhty or not considering disks' health also.
*
* @param isHealthy
* if or not node is healthy
*/
private synchronized void setHealthy(boolean isHealthy) {
this.isHealthy = isHealthy;
}
/**
* Returns output from health script. if node is healthy then an empty string
* is returned.
*
* @return output from health script
*/
public String getHealthReport() {
return healthReport;
}
/**
* Sets the health report from the node health script. Also set the disks'
* health info obtained from DiskHealthCheckerService.
*
* @param healthReport
*/
private synchronized void setHealthReport(String healthReport) {
this.healthReport = healthReport;
}
/**
* Returns time stamp when node health script was last run.
*
* @return timestamp when node health script was last run
*/
public long getLastReportedTime() {
return lastReportedTime;
}
/**
* Sets the last run time of the node health script.
*
* @param lastReportedTime
*/
private synchronized void setLastReportedTime(long lastReportedTime) {
this.lastReportedTime = lastReportedTime;
}
/**
* Method used to determine if or not node health monitoring service should be
* started or not. Returns true if following conditions are met:
*
*
*
Path to Node health check script is not empty
*
Node health check script file exists
*
*
* @return true if node health monitoring service can be started.
*/
public static boolean shouldRun(String healthScript) {
if (healthScript == null || healthScript.trim().isEmpty()) {
return false;
}
File f = new File(healthScript);
return f.exists() && FileUtil.canExecute(f);
}
private synchronized void setHealthStatus(boolean isHealthy, String output) {
LOG.info("health status being set as " + output);
this.setHealthy(isHealthy);
this.setHealthReport(output);
}
private synchronized void setHealthStatus(boolean isHealthy, String output,
long time) {
LOG.info("health status being set as " + output);
this.setHealthStatus(isHealthy, output);
this.setLastReportedTime(time);
}
/**
* Used only by tests to access the timer task directly
* @return the timer task
*/
public TimerTask getTimerTask() {
return timer;
}
}
