org.apache.bookkeeper.net.ScriptBasedMapping Maven / Gradle / Ivy
/*
* 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.bookkeeper.net;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
import org.apache.bookkeeper.util.Shell.ShellCommandExecutor;
import org.apache.commons.configuration.Configuration;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This class implements the {@link DNSToSwitchMapping} interface using a
* script configured via the
* {@link CommonConfigurationKeys#NET_TOPOLOGY_SCRIPT_FILE_NAME_KEY} option.
*
* It contains a static class RawScriptBasedMapping that performs
* the work: reading the configuration parameters, executing any defined
* script, handling errors and such like. The outer
* class extends {@link CachedDNSToSwitchMapping} to cache the delegated
* queries.
*
* This DNS mapper's {@link #isSingleSwitch()} predicate returns
* true if and only if a script is defined.
*/
public final class ScriptBasedMapping extends CachedDNSToSwitchMapping {
/**
* Minimum number of arguments: {@value}.
*/
static final int MIN_ALLOWABLE_ARGS = 1;
/**
* Default number of arguments: {@value}.
*/
static final int DEFAULT_ARG_COUNT = CommonConfigurationKeys.NET_TOPOLOGY_SCRIPT_NUMBER_ARGS_DEFAULT;
/**
* Key to the script filename {@value}.
*/
static final String SCRIPT_FILENAME_KEY = CommonConfigurationKeys.NET_TOPOLOGY_SCRIPT_FILE_NAME_KEY;
/**
* Key to the argument count that the script supports
* {@value}.
*/
static final String SCRIPT_ARG_COUNT_KEY = CommonConfigurationKeys.NET_TOPOLOGY_SCRIPT_NUMBER_ARGS_KEY;
/**
* Text used in the {@link #toString()} method if there is no string
* {@value}.
*/
public static final String NO_SCRIPT = "no script";
/**
* Create an instance with the default configuration.
*
* Calling {@link #setConf(Configuration)} will trigger a
* re-evaluation of the configuration settings and so be used to
* set up the mapping script.
*
*/
public ScriptBasedMapping() {
super(new RawScriptBasedMapping());
}
/**
* Create an instance from the given configuration.
* @param conf configuration
*/
public ScriptBasedMapping(Configuration conf) {
this();
setConf(conf);
}
/**
* Get the cached mapping and convert it to its real type.
* @return the inner raw script mapping.
*/
private RawScriptBasedMapping getRawMapping() {
return (RawScriptBasedMapping) rawMapping;
}
@Override
public Configuration getConf() {
return getRawMapping().getConf();
}
@Override
public String toString() {
return "script-based mapping with " + getRawMapping().toString();
}
/**
* {@inheritDoc}
*
*
This will get called in the superclass constructor, so a check is needed
* to ensure that the raw mapping is defined before trying to relaying a null
* configuration.
* @param conf
*/
@Override
public void setConf(Configuration conf) {
super.setConf(conf);
getRawMapping().setConf(conf);
}
/**
* This is the uncached script mapping that is fed into the cache managed
* by the superclass {@link CachedDNSToSwitchMapping}.
*/
private static final class RawScriptBasedMapping extends AbstractDNSToSwitchMapping {
private String scriptName;
private int maxArgs; //max hostnames per call of the script
private static final Logger LOG = LoggerFactory.getLogger(RawScriptBasedMapping.class);
/*
* extract 'scriptName' and 'maxArgs' parameters from the conf and throw
* RuntimeException if 'scriptName' is null. Also for sanity check
* purpose try executing the script with no arguments. Here it is
* expected that running script with no arguments would do sanity check
* of the script and the env, and return successfully if script and env.
* are valid. If sanity check of the script with no argument fails then
* throw RuntimeException.
*
*/
@Override
protected void validateConf() {
Configuration conf = getConf();
if (conf != null) {
String scriptNameConfValue = conf.getString(SCRIPT_FILENAME_KEY);
if (StringUtils.isNotBlank(scriptNameConfValue)) {
scriptName = scriptNameConfValue;
maxArgs = conf.getInt(SCRIPT_ARG_COUNT_KEY, DEFAULT_ARG_COUNT);
} else {
scriptName = null;
maxArgs = 0;
}
} else {
scriptName = null;
maxArgs = 0;
}
if (null == scriptName) {
throw new RuntimeException("No network topology script is found when using script"
+ " based DNS resolver.");
} else {
File dir = null;
String userDir;
if ((userDir = System.getProperty("user.dir")) != null) {
dir = new File(userDir);
}
String[] execString = { this.scriptName };
ShellCommandExecutor s = new ShellCommandExecutor(execString, dir);
try {
s.execute();
} catch (Exception e) {
LOG.error("Conf validation failed. Got exception for sanity check of script: " + this.scriptName,
e);
throw new RuntimeException(
"Conf validation failed. Got exception for sanity check of script: " + this.scriptName, e);
}
}
}
/**
* Constructor. The mapping is not ready to use until
* {@link #setConf(Configuration)} has been called
*/
public RawScriptBasedMapping() {
}
@Override
public List resolve(List names) {
List m = new ArrayList(names.size());
if (names.isEmpty()) {
return m;
}
if (scriptName == null) {
return null;
}
String output = runResolveCommand(names);
if (output != null) {
StringTokenizer allSwitchInfo = new StringTokenizer(output);
while (allSwitchInfo.hasMoreTokens()) {
String switchInfo = allSwitchInfo.nextToken();
m.add(switchInfo);
}
if (m.size() != names.size()) {
// invalid number of entries returned by the script
LOG.error("Script " + scriptName + " returned " + m.size() + " values when "
+ names.size() + " were expected.");
return null;
}
} else {
// an error occurred. return null to signify this.
// (exn was already logged in runResolveCommand)
return null;
}
return m;
}
/**
* Build and execute the resolution command. The command is
* executed in the directory specified by the system property
* "user.dir" if set; otherwise the current working directory is used
* @param args a list of arguments
* @return null if the number of arguments is out of range,
* or the output of the command.
*/
private String runResolveCommand(List args) {
int loopCount = 0;
if (args.size() == 0) {
return null;
}
StringBuilder allOutput = new StringBuilder();
int numProcessed = 0;
if (maxArgs < MIN_ALLOWABLE_ARGS) {
LOG.warn("Invalid value " + maxArgs + " for " + SCRIPT_ARG_COUNT_KEY
+ "; must be >= " + MIN_ALLOWABLE_ARGS);
return null;
}
while (numProcessed != args.size()) {
int start = maxArgs * loopCount;
List cmdList = new ArrayList();
cmdList.add(scriptName);
for (numProcessed = start;
numProcessed < (start + maxArgs) && numProcessed < args.size();
numProcessed++) {
cmdList.add(args.get(numProcessed));
}
File dir = null;
String userDir;
if ((userDir = System.getProperty("user.dir")) != null) {
dir = new File(userDir);
}
ShellCommandExecutor s = new ShellCommandExecutor(cmdList.toArray(new String[cmdList.size()]), dir);
try {
s.execute();
allOutput.append(s.getOutput()).append(" ");
} catch (Exception e) {
LOG.warn("Exception running: {} Exception message: {}", s, e.getMessage());
return null;
}
loopCount++;
}
return allOutput.toString();
}
/**
* Declare that the mapper is single-switched if a script was not named
* in the configuration.
* @return true iff there is no script
*/
@Override
public boolean isSingleSwitch() {
return scriptName == null;
}
@Override
public String toString() {
return scriptName != null ? ("script " + scriptName) : NO_SCRIPT;
}
@Override
public void reloadCachedMappings() {
// Nothing to do here, since RawScriptBasedMapping has no cache, and
// does not inherit from CachedDNSToSwitchMapping
}
}
}