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auto-healer-zookeper
Commit 75d1cc44 authored by tammam.alsoleman's avatar tammam.alsoleman
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.idea/.gitignore 0 → 100644
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# Default ignored files
/shelf/
/workspace.xml
.idea/autohealer-exercise2.iml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
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.idea/compiler.xml 0 → 100644
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<module name="autohealer" />
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<module name="flaky.worker" target="1.8" />
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.idea/encodings.xml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
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<file url="file://$PROJECT_DIR$/autohealer/src/main/java" charset="UTF-8" />
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<file url="file://$PROJECT_DIR$/transientworker/src/main/resources" charset="UTF-8" />
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\ No newline at end of file
.idea/jarRepositories.xml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
<component name="RemoteRepositoriesConfiguration">
<remote-repository>
<option name="id" value="central" />
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.idea/misc.xml 0 → 100644
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.idea/vcs.xml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
<component name="VcsDirectoryMappings">
<mapping directory="$PROJECT_DIR$" vcs="Git" />
</component>
</project>
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README.md 0 → 100644
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# Auto-healer using Zookeeper
In cloud computing, auto-healing is a feature used to monitor a cluster and detect faulty application instances.
If a faulty instance is detected, the node is shut down and a new node is created with a healthy application instance.
In this practical assignment we will implement a very basic auto healer which will monitor a group of worker instances.
You are given a worker application
The worker instances are running a very complex computation that tends to crash in a particular edge case that the author did not account for.
Our mission is to maintain at least N worker nodes at any given moment.
If a worker crashes, we need to start a new worker.
### Build the Autohealer as a jar
### Run the autohealer, which in turn would launch and maintain 10 workers
```
java -jar target/autohealer-1.0-SNAPSHOT-jar-with-dependencies.jar <number of workers> <path to woker jar>
```
#### Example:
```
java -jar target/autohealer-1.0-SNAPSHOT-jar-with-dependencies.jar 10 "../transientworker/target/transientworker-1.0-SNAPSHOT-jar-with-dependencies.jar"
```
autohealer/.idea/compiler.xml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
<component name="CompilerConfiguration">
<annotationProcessing>
<profile name="Maven default annotation processors profile" enabled="true">
<sourceOutputDir name="target/generated-sources/annotations" />
<sourceTestOutputDir name="target/generated-test-sources/test-annotations" />
<outputRelativeToContentRoot value="true" />
<module name="autohealer" />
</profile>
</annotationProcessing>
</component>
</project>
\ No newline at end of file
autohealer/.idea/encodings.xml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
<component name="Encoding">
<file url="file://$PROJECT_DIR$/src/main/java" charset="UTF-8" />
<file url="file://$PROJECT_DIR$/src/main/resources" charset="UTF-8" />
</component>
</project>
\ No newline at end of file
autohealer/.idea/jarRepositories.xml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
<component name="RemoteRepositoriesConfiguration">
<remote-repository>
<option name="id" value="central" />
<option name="name" value="Central Repository" />
<option name="url" value="https://repo.maven.apache.org/maven2" />
</remote-repository>
<remote-repository>
<option name="id" value="central" />
<option name="name" value="Maven Central repository" />
<option name="url" value="https://repo1.maven.org/maven2" />
</remote-repository>
<remote-repository>
<option name="id" value="jboss.community" />
<option name="name" value="JBoss Community repository" />
<option name="url" value="https://repository.jboss.org/nexus/content/repositories/public/" />
</remote-repository>
</component>
</project>
\ No newline at end of file
autohealer/.idea/misc.xml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
<component name="ExternalStorageConfigurationManager" enabled="true" />
<component name="MavenProjectsManager">
<option name="originalFiles">
<list>
<option value="$PROJECT_DIR$/pom.xml" />
</list>
</option>
</component>
<component name="ProjectRootManager" version="2" languageLevel="JDK_17" default="true" project-jdk-name="17" project-jdk-type="JavaSDK" />
</project>
\ No newline at end of file
autohealer/.idea/vcs.xml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
<component name="VcsDirectoryMappings">
<mapping directory="$PROJECT_DIR$/.." vcs="Git" />
</component>
</project>
\ No newline at end of file
autohealer/.idea/workspace.xml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
<component name="AutoImportSettings">
<option name="autoReloadType" value="SELECTIVE" />
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<component name="ChangeListManager">
<list default="true" id="09c2cdeb-da7c-4fc3-8e7b-a0edfcd38ff5" name="Changes" comment="" />
<option name="SHOW_DIALOG" value="false" />
<option name="HIGHLIGHT_CONFLICTS" value="true" />
<option name="HIGHLIGHT_NON_ACTIVE_CHANGELIST" value="false" />
<option name="LAST_RESOLUTION" value="IGNORE" />
</component>
<component name="Git.Settings">
<option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$/.." />
</component>
<component name="MarkdownSettingsMigration">
<option name="stateVersion" value="1" />
</component>
<component name="MavenImportPreferences">
<option name="generalSettings">
<MavenGeneralSettings>
<option name="useMavenConfig" value="true" />
</MavenGeneralSettings>
</option>
</component>
<component name="ProjectId" id="2aUIDMBn1fiD4OfFEsFyf5ggKq4" />
<component name="ProjectLevelVcsManager" settingsEditedManually="true" />
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<option name="hideEmptyMiddlePackages" value="true" />
<option name="showLibraryContents" value="true" />
</component>
<component name="PropertiesComponent"><![CDATA[{
"keyToString": {
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}]]></component>
<component name="SpellCheckerSettings" RuntimeDictionaries="0" Folders="0" CustomDictionaries="0" DefaultDictionary="application-level" UseSingleDictionary="true" transferred="true" />
<component name="TaskManager">
<task active="true" id="Default" summary="Default task">
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<State />
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</map>
</option>
</component>
</project>
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autohealer/pom.xml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.example</groupId>
<artifactId>autohealer</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<maven.compiler.source>17</maven.compiler.source>
<maven.compiler.target>17</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.11.0</version>
<configuration>
<source>17</source>
<target>17</target>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.9.1</version>
</dependency>
</dependencies>
</project>
\ No newline at end of file
autohealer/src/main/java/Application.java 0 → 100644
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/*
* MIT License
*
* Copyright (c) 2019 Michael Pogrebinsky - Distributed Systems & Cloud Computing with Java
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
import org.apache.zookeeper.KeeperException;
import java.io.IOException;
public class Application {
public static void main(String[] args) throws IOException, InterruptedException, KeeperException {
if (args.length != 2) {
System.out.println("Expecting parameters <number of workers> <path to worker jar file>");
System.exit(1);
}
int numberOfWorkers = Integer.parseInt(args[0]);
String pathToWorkerProgram = args[1];
Autohealer autohealer = new Autohealer(numberOfWorkers, pathToWorkerProgram);
autohealer.connectToZookeeper();
autohealer.startWatchingWorkers();
autohealer.run();
autohealer.close();
}
}
autohealer/src/main/java/Autohealer.java 0 → 100644
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/*
* MIT License
*
* Copyright (c) 2019 Michael Pogrebinsky - Distributed Systems & Cloud Computing with Java
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
import org.apache.zookeeper.*;
import java.io.File;
import java.io.IOException;
public class Autohealer implements Watcher {
private static final String ZOOKEEPER_ADDRESS = "172.29.3.101:2181";
private static final int SESSION_TIMEOUT = 3000;
// Parent Znode where each worker stores an ephemeral child to indicate it is alive
private static final String AUTOHEALER_ZNODES_PATH = "/workers";
// Path to the worker jar
private final String pathToProgram;
// The number of worker instances we need to maintain at all times
private final int numberOfWorkers;
private ZooKeeper zooKeeper;
public Autohealer(int numberOfWorkers, String pathToProgram) {
this.numberOfWorkers = numberOfWorkers;
this.pathToProgram = pathToProgram;
}
public void startWatchingWorkers() throws KeeperException, InterruptedException {
if (zooKeeper.exists(AUTOHEALER_ZNODES_PATH, false) == null) {
zooKeeper.create(AUTOHEALER_ZNODES_PATH, new byte[]{}, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
launchWorkersIfNecessary();
}
public void connectToZookeeper() throws IOException {
this.zooKeeper = new ZooKeeper(ZOOKEEPER_ADDRESS, SESSION_TIMEOUT, this);
}
public void run() throws InterruptedException {
synchronized (zooKeeper) {
zooKeeper.wait();
}
}
public void close() throws InterruptedException {
zooKeeper.close();
}
@Override
public void process(WatchedEvent event) {
switch (event.getType()) {
case None:
if (event.getState() == Event.KeeperState.SyncConnected) {
System.out.println("Successfully connected to Zookeeper");
} else {
synchronized (zooKeeper) {
System.out.println("Disconnected from Zookeeper event");
zooKeeper.notifyAll();
}
}
break;
/**
* Add states code here to respond to the relevant events
*/
}
}
private void launchWorkersIfNecessary() {
/**
* Implement this method to watch and launch new workers if necessary
*/
}
/**
* Helper method to start a single worker
* @throws IOException
*/
private void startNewWorker() throws IOException {
File file = new File(pathToProgram);
String command = "java -jar " + file.getName();
System.out.println(String.format("Launching worker instance : %s ", command));
Runtime.getRuntime().exec(command, null, file.getParentFile());
}
}
transientworker/pom.xml 0 → 100644
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<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.example</groupId>
<artifactId>transientworker</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<maven.compiler.source>17</maven.compiler.source>
<maven.compiler.target>17</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.11.0</version>
<configuration>
<source>17</source>
<target>17</target>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.9.1</version>
</dependency>
</dependencies>
</project>
\ No newline at end of file
transientworker/src/main/java/Application.java 0 → 100644
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/*
* MIT License
*
* Copyright (c) 2019 Michael Pogrebinsky - Distributed Systems & Cloud Computing with Java
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
import org.apache.zookeeper.KeeperException;
import java.io.IOException;
public class Application {
public static void main(String[] args) throws IOException, KeeperException, InterruptedException {
Worker worker = new Worker();
worker.connectToZookeeper();
worker.work();
}
}
transientworker/src/main/java/Worker.java 0 → 100644
View file @ 75d1cc44
/*
* MIT License
*
* Copyright (c) 2019 Michael Pogrebinsky - Distributed Systems & Cloud Computing with Java
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.ZooKeeper;
import java.io.IOException;
import java.util.Random;
import java.util.concurrent.locks.LockSupport;
public class Worker {
private static final String ZOOKEEPER_ADDRESS = "172.29.3.101:2181";
private static final int SESSION_TIMEOUT = 3000;
// Parent Znode where each worker stores an ephemeral child to indicate it is alive
private static final String AUTOHEALER_ZNODES_PATH = "/workers";
private static final float CHANCE_TO_FAIL = 0.1F;
private final Random random = new Random();
private ZooKeeper zooKeeper;
public void connectToZookeeper() throws IOException {
this.zooKeeper = new ZooKeeper(ZOOKEEPER_ADDRESS, SESSION_TIMEOUT, event -> {
});
}
public void work() throws KeeperException, InterruptedException {
addChildZnode();
while (true) {
System.out.println("Working...");
LockSupport.parkNanos(1000);
if (random.nextFloat() < CHANCE_TO_FAIL) {
System.out.println("Critical error happened");
throw new RuntimeException("Oops");
}
}
}
private void addChildZnode() throws KeeperException, InterruptedException {
zooKeeper.create(AUTOHEALER_ZNODES_PATH + "/worker_",
new byte[]{},
ZooDefs.Ids.OPEN_ACL_UNSAFE,
CreateMode.EPHEMERAL_SEQUENTIAL);
}
}
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