[Hadoop] Zookeeper 安装部署与简单操作

偏执的太偏执、 2022-05-15 03:17 197阅读 0赞

Zookeeper - 负责分布式系统的协调服务。

Hadoop集群中，zk节点的数量 n/2+1个，其中n>1，一般集群中zk的数量为3/5/7/9个。多个zk可以搭在同一个节点上。

## 1. Zookeeper下载安装 ##

我的环境使用的是cdh5.7.0版本的套件，所以zookeeper也选择对应的版本下载。

下载

[hadoop@hadoop000 software]$ wget http://archive.cloudera.com/cdh5/cdh/5/zookeeper-3.4.5-cdh5.7.0.tar.gz

解压安装

[hadoop@hadoop000 software]$ tar -zxvf zookeeper-3.4.5-cdh5.7.0.tar.gz -C ~/app/

配置环境变量

export ZK_HOME=/home/hadoop/app/zookeeper-3.4.5-cdh5.7.0
    export PATH=$ZK_HOME/bin:$PATH

配置zk

[hadoop@hadoop000 zookeeper-3.4.5-cdh5.7.0]$ cp conf/zoo_sample.cfg conf/zoo.cfg
    [hadoop@hadoop000 zookeeper-3.4.5-cdh5.7.0]$ vi conf/zoo.cfg
    dataDir=/home/hadoop/tmp/zookeeper

启动zk

[hadoop@hadoop000 zookeeper-3.4.5-cdh5.7.0]$ cd bin/
    # 启动
    [hadoop@hadoop000 bin]$ ./zkServer.sh start
    JMX enabled by default
    Using config: /home/hadoop/app/zookeeper-3.4.5-cdh5.7.0/bin/../conf/zoo.cfg
    Starting zookeeper ... STARTED
    [hadoop@hadoop000 bin]$
    
    
    # 重启
    [hadoop@hadoop000 bin]$ ./zkServer.sh restart

查看启动状态

# zk命令直接查看
    [hadoop@hadoop000 bin]$ ./zkServer.sh status
    JMX enabled by default
    Using config: /home/hadoop/app/zookeeper-3.4.5-cdh5.7.0/bin/../conf/zoo.cfg
    Mode: standalone    # zk启动模式为standalone
    [hadoop@hadoop000 bin]$
    
    # 也可以通过jps查看zk进程QuorumPeerMain是否存活
    [hadoop@hadoop000 bin]$ jps
    5744 DataNode
    22305 QuorumPeerMain        -- zk
    5545 NameNode
    6361 NodeManager
    6010 SecondaryNameNode
    22347 Jps
    6236 ResourceManager
    3439 Nailgun
    [hadoop@hadoop000 bin]$

停止zk

[hadoop@hadoop000 bin]$ ./zkServer.sh stop
    JMX enabled by default
    Using config: /home/hadoop/app/zookeeper-3.4.5-cdh5.7.0/bin/../conf/zoo.cfg
    Stopping zookeeper ... STOPPED
    [hadoop@hadoop000 bin]$

查看zk的dataDir

[hadoop@hadoop000 zookeeper]$ ls -ltr
    total 4
    drwxrwxr-x. 2 hadoop hadoop 23 Aug 15 20:23 version-2   # 一个路径
    -rw-rw-r--. 1 hadoop hadoop  5 Aug 15 20:28 zookeeper_server.pid   # zk server进程id号
    [hadoop@hadoop000 zookeeper]$

## 2. zk的基本数据模型 ##

zk的基本数据模型为一个树形结构（类似文件系统结构）。

zk的节点（znode）分为临时节点和永久节点。

临时节点对当前session有效，永久节点永久有效。（同HIVE UDF）

永久节点下面可以挂子节点，临时节点下面不能再挂任何节点。

znode特点：

znode：每一个节点都有一个id，id不会重复；每一个id都有一个父id（pid）

每一个节点上的数据发生了变化，这时候会引发数据版本号cversion变化（版本号+1）

znode上面不要存放太大的数据（几个kb），比如配置文件等。

## 3. Zookeeper 基本操作 ##

其中zk客户端来连接zk server

# 可以启动一个zk client来查看version-2下面文件的具体内容
    # 启动一个zk client, client会连接到zk server的2181端口
    [hadoop@hadoop000 bin]$ ./zkCli.sh
    Connecting to localhost:2181
    ...
    
    WATCHER::
    
    WatchedEvent state:SyncConnected type:None path:null
    [zk: localhost:2181(CONNECTED) 0]

使用帮助

# 使用帮助
    [zk: localhost:2181(CONNECTED) 0] help    # 从这里开始每下一个命令这里序号+1

查看路径

# 查看路径
    [zk: localhost:2181(CONNECTED) 1] ls /
    [zookeeper]
    [zk: localhost:2181(CONNECTED) 2] ls /zookeeper
    [quota]
    [zk: localhost:2181(CONNECTED) 3] ls /zookeeper/quota
    []
    [zk: localhost:2181(CONNECTED) 4]

查看节点具体数据

# 查看内容
    [zk: localhost:2181(CONNECTED) 4] get /zookeeper/quota
                                             # 这里空着一行代表没有数据，下面的内容为数据的属性
    cZxid = 0x0
    ctime = Thu Jan 01 08:00:00 CST 1970
    mZxid = 0x0
    mtime = Thu Jan 01 08:00:00 CST 1970
    pZxid = 0x0
    cversion = 0
    dataVersion = 0
    aclVersion = 0
    ephemeralOwner = 0x0
    dataLength = 0
    numChildren = 0
    [zk: localhost:2181(CONNECTED) 5]
    
    # ls2 = ls + get
    [zk: localhost:2181(CONNECTED) 5] ls2 /zookeeper/quota
    []                                                # 取出来数据为空的
    cZxid = 0x0
    ctime = Thu Jan 01 08:00:00 CST 1970
    mZxid = 0x0
    mtime = Thu Jan 01 08:00:00 CST 1970
    pZxid = 0x0
    cversion = 0
    dataVersion = 0
    aclVersion = 0
    ephemeralOwner = 0x0
    dataLength = 0
    numChildren = 0
    [zk: localhost:2181(CONNECTED) 6]

创建节点（顺序节点和临时节点）并查看属性

# 创建一个节点（znode）
    # create -e 创建临时节点；create -s 创建顺序(sequence)节点
    # 创建一个节点叫/node_a，数据为hello
    [zk: localhost:2181(CONNECTED) 13] create -s /node_a hello
    Created /node_a0000000003
    [zk: localhost:2181(CONNECTED) 14] ls /
    [zookeeper, node_a0000000003]
    [zk: localhost:2181(CONNECTED) 15] get /node_a0000000003
    hello                                            # 数据内容
    cZxid = 0x5                                    # 创建时的id
    ctime = Wed Aug 15 21:05:23 CST 2018            # 创建时间
    mZxid = 0x5
    mtime = Wed Aug 15 21:05:23 CST 2018            # 修改时间
    pZxid = 0x5                                    # 最新(最后更新的)的子节点id
    cversion = 0                                    # 版本号
    dataVersion = 0                                # 数据版本号
    aclVersion = 0
    ephemeralOwner = 0x0                            # 是否为临时的节点（0x0不是，为永久节点）
    dataLength = 5                                    # 数据长度
    numChildren = 0                                    # 子节点数
    [zk: localhost:2181(CONNECTED) 16]
    
    # 在上面的节点下创建一个临时节点，对比属性变化
    [zk: localhost:2181(CONNECTED) 16] create -e /node_a0000000003/tmp hello
    Created /node_a0000000003/tmp
    [zk: localhost:2181(CONNECTED) 17] get /node_a0000000003
    hello                                            # 数据内容不变
    cZxid = 0x5
    ctime = Wed Aug 15 21:05:23 CST 2018
    mZxid = 0x5
    mtime = Wed Aug 15 21:05:23 CST 2018
    pZxid = 0x6                                    # 最后更新的子节点id发生变化
    cversion = 1                                    # 版本号变化
    dataVersion = 0
    aclVersion = 0
    ephemeralOwner = 0x0
    dataLength = 5
    numChildren = 1                                # 子节点数+1
    
    # 查看临时节点
    [zk: localhost:2181(CONNECTED) 18] get /node_a0000000003/tmp
    hello
    cZxid = 0x6                                    # 与上面父节点的pZid一致
    ctime = Wed Aug 15 21:13:23 CST 2018
    mZxid = 0x6
    mtime = Wed Aug 15 21:13:23 CST 2018
    pZxid = 0x6
    cversion = 0
    dataVersion = 0
    aclVersion = 0
    ephemeralOwner = 0x1653d96c64c0000                # 临时节点
    dataLength = 5
    numChildren = 0
    [zk: localhost:2181(CONNECTED) 19]
    
    # 关掉当前窗口再重新开一个新窗口，再次查看/node_a0000000003/节点，下面的临时节点tmp已经不存在了，即临时节点是当前session有效的
    [zk: localhost:2181(CONNECTED) 0] ls /node_a0000000003
    []
    [zk: localhost:2181(CONNECTED) 1]
    
    # 临时节点下面不能再挂任何节点
    [zk: localhost:2181(CONNECTED) 14] create -e /node_a0000000003/tmp hello
    Created /node_a0000000003/tmp
    [zk: localhost:2181(CONNECTED) 15] create -e /node_a0000000003/tmp/test hello
    Ephemerals cannot have children: /node_a0000000003/tmp/test
    [zk: localhost:2181(CONNECTED) 16]
    
    
    # 创建几个顺序节点
    [zk: localhost:2181(CONNECTED) 3] create -s /node_a0000000003/seq zookeeper
    Created /node_a0000000003/seq0000000001
    [zk: localhost:2181(CONNECTED) 4] create -s /node_a0000000003/seq zookeeper
    Created /node_a0000000003/seq0000000002
    [zk: localhost:2181(CONNECTED) 5] create -s /node_a0000000003/seq zookeeper
    Created /node_a0000000003/seq0000000003
    [zk: localhost:2181(CONNECTED) 6] create -s /node_a0000000003/seq zookeeper
    Created /node_a0000000003/seq0000000004
    [zk: localhost:2181(CONNECTED) 7] create -s /node_a0000000003/seq zookeeper
    Created /node_a0000000003/seq0000000005
    [zk: localhost:2181(CONNECTED) 8] ls /node_a0000000003
    [seq0000000005, seq0000000003, seq0000000004, seq0000000001, seq0000000002]
    [zk: localhost:2181(CONNECTED) 9]
    
    # 一次性创建连续的多层节点是不行的。但是通过Curator提供的API可以实现
    [zk: localhost:2181(CONNECTED) 13] create -s /node_a0000000003/a/b/c abc
    Node does not exist: /node_a0000000003/a/b/c
    [zk: localhost:2181(CONNECTED) 14]

修改节点上的数据内容（set和delete的时候要注意version）

# 修改节点上数据的内容，dataVersion + 1
    [zk: localhost:2181(CONNECTED) 16] set /node_a0000000003 hello_new
    cZxid = 0x5
    ctime = Wed Aug 15 21:05:23 CST 2018
    mZxid = 0x13
    mtime = Wed Aug 15 21:35:45 CST 2018
    pZxid = 0x11
    cversion = 8
    dataVersion = 1                        # dataVersion + 1
    aclVersion = 0
    ephemeralOwner = 0x0
    dataLength = 9
    numChildren = 6
    [zk: localhost:2181(CONNECTED) 17] get /node_a0000000003
    hello_new
    cZxid = 0x5
    ctime = Wed Aug 15 21:05:23 CST 2018
    mZxid = 0x13
    mtime = Wed Aug 15 21:35:45 CST 2018
    pZxid = 0x11
    cversion = 8
    dataVersion = 1
    aclVersion = 0
    ephemeralOwner = 0x0
    dataLength = 9
    numChildren = 6
    [zk: localhost:2181(CONNECTED) 18]
    
    # 当前dataVersion为1，指定修改1版本的数据:set /znode data version 
    [zk: localhost:2181(CONNECTED) 18] set /node_a0000000003 hello_2 1
    cZxid = 0x5
    ctime = Wed Aug 15 21:05:23 CST 2018
    mZxid = 0x14
    mtime = Wed Aug 15 21:38:33 CST 2018
    pZxid = 0x11
    cversion = 8
    dataVersion = 2
    aclVersion = 0
    ephemeralOwner = 0x0
    dataLength = 7
    numChildren = 6
    [zk: localhost:2181(CONNECTED) 19] get /node_a0000000003
    hello_2                                            # 数据成功被修改
    cZxid = 0x5
    ctime = Wed Aug 15 21:05:23 CST 2018
    mZxid = 0x14
    mtime = Wed Aug 15 21:38:33 CST 2018
    pZxid = 0x11
    cversion = 8
    dataVersion = 2                                    # 数据的版本号变为2
    aclVersion = 0
    ephemeralOwner = 0x0
    dataLength = 7
    numChildren = 6
    [zk: localhost:2181(CONNECTED) 20]
    
    # 再次修改version为1的数据，会报错提示版本号为1的数据不存在（这是一个乐观锁）
    [zk: localhost:2181(CONNECTED) 20] set /node_a0000000003 hello_3 1
    version No is not valid : /node_a0000000003
    [zk: localhost:2181(CONNECTED) 21]

删除节点

[zk: localhost:2181(CONNECTED) 21] ls /node_a0000000003
    [seq0000000005, seq0000000003, seq0000000004, seq0000000001, tmp, seq0000000002]
    [zk: localhost:2181(CONNECTED) 22] delete /node_a0000000003/seq000000000
    seq0000000005   seq0000000003   seq0000000004   seq0000000001   seq0000000002
    [zk: localhost:2181(CONNECTED) 22] delete /node_a0000000003/seq0000000001
    [zk: localhost:2181(CONNECTED) 23] ls /node_a0000000003
    [seq0000000005, seq0000000003, seq0000000004, tmp, seq0000000002]
    [zk: localhost:2181(CONNECTED) 24]
    
    # 删除时注意版本号
    # 修改一下/node_a0000000003/seq0000000002的数据，dataVersion变为1。删除时要关注版本号
    [zk: localhost:2181(CONNECTED) 24] get /node_a0000000003/seq0000000002
    zookeeper
    cZxid = 0xa
    ctime = Wed Aug 15 21:24:19 CST 2018
    mZxid = 0xa
    mtime = Wed Aug 15 21:24:19 CST 2018
    pZxid = 0xa
    cversion = 0
    dataVersion = 0
    aclVersion = 0
    ephemeralOwner = 0x0
    dataLength = 9
    numChildren = 0
    [zk: localhost:2181(CONNECTED) 25] set /node_a0000000003/seq000000000
    seq0000000005   seq0000000003   seq0000000004   seq0000000002
    [zk: localhost:2181(CONNECTED) 25] set /node_a0000000003/seq0000000002 zookeeper_1
    cZxid = 0xa
    ctime = Wed Aug 15 21:24:19 CST 2018
    mZxid = 0x17
    mtime = Wed Aug 15 21:50:03 CST 2018
    pZxid = 0xa
    cversion = 0
    dataVersion = 1
    aclVersion = 0
    ephemeralOwner = 0x0
    dataLength = 11
    numChildren = 0
    [zk: localhost:2181(CONNECTED) 26] get /node_a0000000003/seq0000000002
    zookeeper_1
    cZxid = 0xa
    ctime = Wed Aug 15 21:24:19 CST 2018
    mZxid = 0x17
    mtime = Wed Aug 15 21:50:03 CST 2018
    pZxid = 0xa
    cversion = 0
    dataVersion = 1
    aclVersion = 0
    ephemeralOwner = 0x0
    dataLength = 11
    numChildren = 0
    [zk: localhost:2181(CONNECTED) 27] delete /node_a0000000003/seq0000000002 0
    version No is not valid : /node_a0000000003/seq0000000002
    [zk: localhost:2181(CONNECTED) 28] delete /node_a0000000003/seq0000000002 1
    [zk: localhost:2181(CONNECTED) 29] ls /node_a0000000003
    [seq0000000005, seq0000000003, seq0000000004, tmp]        # 2已经被删除了
    [zk: localhost:2181(CONNECTED) 30]

## 4. zk四字命令 ##

[http://zookeeper.apache.org/][http_zookeeper.apache.org] -> Documentation -> Release 3.4.13 -> administrator's Guide -> Zookeeper Commands: [The Four Letter Words][].

CentOS7默认没有安装netcat，要先安装

[root@hadoop01 ~]# yum -y install nmap-ncat
    [root@hadoop01 yum.repos.d]# nc -help

netcat命令已经可以使用

[root@hadoop01 yum.repos.d]# echo mntr | nc localhost 2181
    zk_version	3.4.5-cdh5.7.0--1, built on 03/23/2016 18:31 GMT
    zk_avg_latency	0
    zk_max_latency	43
    zk_min_latency	0
    zk_packets_received	475
    zk_packets_sent	474
    zk_num_alive_connections	1
    zk_outstanding_requests	0
    zk_server_state	standalone
    zk_znode_count	6
    zk_watch_count	0
    zk_ephemerals_count	0
    zk_approximate_data_size	87
    zk_open_file_descriptor_count	28
    zk_max_file_descriptor_count	4096
    [root@hadoop01 yum.repos.d]#

stat - 查看zk客户端连接情况

[root@hadoop000 ~]# echo stat | nc localhost 2181
    Zookeeper version: 3.4.5-cdh5.7.0--1, built on 03/23/2016 18:31 GMT
    Clients:
     /0:0:0:0:0:0:0:1:55671[1](queued=0,recved=2,sent=2)
     /0:0:0:0:0:0:0:1:55672[0](queued=0,recved=1,sent=0)
    
    Latency min/avg/max: 0/0/24
    Received: 1930
    Sent: 1929
    Connections: 2
    Outstanding: 0
    Zxid: 0x1b
    Mode: standalone
    Node count: 11
    [root@hadoop000 ~]#

ruok - 测试zk server的运行状态

[root@hadoop000 ~]# echo ruok | nc localhost 2181
    imok[root@hadoop000 ~]#

dump - 列出节点和临时节点的一些情况

[root@hadoop000 ~]# echo dump | nc localhost 2181
    SessionTracker dump:
    Session Sets (3):
    0 expire at Thu Aug 16 18:57:04 CST 2018:
    0 expire at Thu Aug 16 18:57:14 CST 2018:
    1 expire at Thu Aug 16 18:57:24 CST 2018:
    	0x1653d96c64c0002
    ephemeral nodes dump:
    Sessions with Ephemerals (0):
    [root@hadoop000 ~]#

其他四字命令参见[zk官方文档][The Four Letter Words]。

[http_zookeeper.apache.org]: http://zookeeper.apache.org/
[The Four Letter Words]: http://zookeeper.apache.org/doc/r3.4.13/zookeeperAdmin.html#sc_zkCommands