Configuration provisioning with Apache Zookeeper

Transcript

1. Zookeeper
   CONFIGURATION PROVISIONING WITH...
   mariusz gil
   

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2. About me
   

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5. Coordination service for
   distributed applications and systems
   

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6. /app/feat_3
   /app/f_2
   /app/f_1
   /servers
   /app
   In-memory file system model
   /
   

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7. clients
   zookeeper cluster
   leader
   

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8. 7use cases name service
   configuration
   group membership
   leader election
   barriers
   queues
   locks
   

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9. many projects Apache Accumulo
   Apache Hadoop MapReduce
   Apache HBase
   Apache Hedwig
   Apache Kafka
   Apache S4
   Apache Solr
   Apache Storm
   Mesos
   Neo4J
   

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10. ZooKeeper usage
    

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11. Installation
    wget http://ftp.ps.pl/pub/apache/zookeeper/stable/zookeeper-3.4.5.tar.gz
    touch conf/zoo.cfg
    vim conf/zoo.cfg
    # STANDALONE ENVIRONMENT
    # tickTime=2000
    # dataDir=/var/zookeeper
    # clientPort=2181
    # DISTRIBUTED ENVIRONMENT
    # tickTime=2000
    # dataDir=/var/zookeeper
    # clientPort=2181
    # initLimit=5
    # syncLimit=2
    # server.1=zoo1:2888:3888
    # server.2=zoo2:2888:3888
    # server.3=zoo3:2888:3888
    bin/zkServer.sh start
    

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12. CLI mode
    bin/zkServer.sh start
    bin/zkCli.sh 127.0.0.1:2181
    [zk: localhost:2181(CONNECTED) 31] help
    ZooKeeper -server host:port cmd args
    connect host:port
    get path [watch]
    ls path [watch]
    set path data [version]
    rmr path
    delquota [-n|-b] path
    quit
    printwatches on|off
    create [-s] [-e] path data acl
    stat path [watch]
    close
    ls2 path [watch]
    history
    listquota path
    setAcl path acl
    getAcl path
    sync path
    redo cmdno
    addauth scheme auth
    delete path [version]
    

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13. CLI mode
    bin/zkServer.sh start
    bin/zkCli.sh 127.0.0.1:2181
    [zk: localhost:2181(CONNECTED) 8] ls /
    [zookeeper]
    ...
    [zk: localhost:2181(CONNECTED) 17] create /app/features/pymk ''
    Created /app/features/pymk
    [zk: localhost:2181(CONNECTED) 20] create /app/features/pymk/enabled 0
    Created /app/features/pymk/enabled
    [zk: localhost:2181(CONNECTED) 24] set /app/features/pymk/enabled 1
    [zk: localhost:2181(CONNECTED) 28] get /app/features/pymk/enabled
    1
    [zk: localhost:2181(CONNECTED) 26] ls /app/features
    [pymk, login, friends, messages]
    [zk: localhost:2181(CONNECTED) 29] rmr /app/features
    [zk: localhost:2181(CONNECTED) 30] ls /app
    []
    bin/zkServer.sh stop
    

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14. PHP + ZooKeeper
    

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15. Edit config.prod.yml file
    Commit to repo
    Wait for CI report
    Build app package
    Deploy to production
    

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16. ZooKeeper cluster
    Web workers Tasks workers
    

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18. $ cd
    $ git clone https://github.com/andreiz/php-zookeeper.git
    $ cd php-zookeeper
    $ phpize
    $ ./configure
    $ make
    $ sudo make install
    Installation of PHP extensions
    

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19. class Zookeeper_Example
    {
    // ...
    /**
    * Set a node to a value.
    */
    public function set($path, $value) {
    if (!$this->zookeeper->exists($path)) {
    $this->makePath($path);
    $this->makeNode($path, $value);
    } else {
    $this->zookeeper->set($path, $value);
    }
    }
    /**
    * Equivalent of "mkdir -p" on ZooKeeper
    */
    public function makePath($path, $value = '') {
    $parts = explode('/', $path);
    $parts = array_filter($parts);
    $subpath = '';
    while (count($parts) > 1) {
    $subpath .= '/' . array_shift($parts);
    if (!$this->zookeeper->exists($subpath)) {
    $this->makeNode($subpath, $value);
    }
    }
    }
    Example 1
    Simple configuration client
    $zk = new Zookeeper_Example('localhost:2181');
    var_dump($zk->get('/'));
    var_dump($zk->getChildren('/'));
    var_dump($zk->set('/test123', 'abc'));
    var_dump($zk->get('/test123'));
    var_dump($zk->getChildren('/'));
    var_dump($zk->set('/foo/001', 'bar1'));
    var_dump($zk->set('/foo/002', 'bar2'));
    var_dump($zk->getChildren('/foo'));
    Tekst
    

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20. class ZookeeperDemo extends Zookeeper {
    /**
    * Watcher method
    */
    public function watcher( $i, $type, $key ) {
    echo "Insider Watcher / ";
    echo "New value for $key is " . $this->get( '/test', array($this, 'watcher' ) ) . "\n";
    }
    }
    $zoo = new ZookeeperDemo('localhost:2181');
    $zoo->get( '/test', array($zoo, 'watcher' ) );
    while( true ) {
    echo '.';
    sleep(2);
    }
    Example 2
    Key change watcher
    

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21. class Worker extends Zookeeper {
    const CONTAINER = '/cluster';
    protected $acl = array(
    array(
    'perms' => Zookeeper::PERM_ALL,
    'scheme' => 'world',
    'id' => 'anyone' ) );
    private $isLeader = false;
    private $znode;
    public function __construct( $host = '', $watcher_cb = null, $recv_timeout = 10000 ) {
    parent::__construct( $host, $watcher_cb, $recv_timeout );
    }
    public function register() {
    if( ! $this->exists( self::CONTAINER ) ) {
    $this->create( self::CONTAINER, null, $this->acl );
    }
    $this->znode = $this->create( self::CONTAINER . '/w-',
    null,
    $this->acl,
    Zookeeper::EPHEMERAL | Zookeeper::SEQUENCE );
    $this->znode = str_replace( self::CONTAINER .'/', '', $this->znode );
    Example 3
    Multiple workers with automatic leader election
    # console 1
    $ php example_worker.php
    I'm registred as: w-0000000001
    Nobody here, I'm the leader
    Leading
    # console 2
    $ php example_worker.php
    I'm registred as: w-0000000002
    I'm watching w-0000000001
    Working
    # console 3
    $ php example_worker.php
    I'm registred as: w-0000000003
    I'm watching w-0000000002
    Working
    

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22. DevOp life?
    

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23. OMG!
    I have to disable feature X for a while
    and change database schema,
    but the rest of the app should works...
    set /app/feature/pymk/enabled 0
    ALTER TABLE...
    set /app/feature/pymk/enabled 1
    

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24. OMG!
    I have to add more cache instances
    and distribute traffic across many
    servers
    set /servers/cache/c6/host 192...
    set /servers/cache/c6/port 11211
    set /servers/cache/c7/host 192...
    set /servers/cache/c7/port 11211
    ls /servers/cache
    

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25. leader
    zookeeper cluster
    service provider
    192.168.12.201
    client
    192.168.12.201
    

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26. leader
    zookeeper cluster
    client
    service provider
    192.168.12.201
    service provider
    192.168.12.123
    192.168.12.123
    

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27. Your app should only know...
    ...where your ZooKeeper is
    

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28. Zookeeper
    CONFIGURATION PROVISIONING WITH...
    mariusz gil
    THANKS
    

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