面试官：说出几个你熟悉的 Zookeeper 命令

首先说明一下环境，使用的zookeeper版本为3.5.10；由于版本不同，命令语法略有差异，提前说明一下，但是基本原理一致，大家可以通过help命令查看自己当前版本的命令语法。

客户端、服务器命令

切换至zookeeper安装目录下的bin目录输入以下命令启动服务器或者客户端

1. 启动ZK服务: ./zkServer.sh start
2. 查看ZK服务状态: ./zkServer.sh status
3. 停止ZK服务: ./zkServer.sh stop
4. 重启ZK服务: ./zkServer.sh restart
5. 连接内部客户端: ./zkCli.sh或者./zkCli.sh -server 127.0.0.1(指定连接服务器IP):2181

节点属性

-cZxid：当前数据结点创建时的事务ID——针对于zookeeper数据结点的管理：我们对结点数据的一些写操作都会导致zookeeper自动地为我们去开启一个事务，并且自动地去为每一个事务维护一个事务ID

• ctime：当前数据结点创建时的时间
• mZxid：当前数据结点最后一次更新时的事务ID
• mtime：当前数据结点最后一次更新时的时间
• pZxid：当前数据节点最后一次修改其子节点**更改的zxid。修改指(增加子节点、删除子节点)，并不指其子节点的数据发生改变；
• cversion：当前数据节点对应子结点的更改次数
• dataVersion：当前结点数据的发生更改的次数
• aclVersion：当前结点的ACL更改次数——类似linux的权限列表，维护的是当前结点的权限列表被修改的次数
• ephemeralOwner：如果结点是临时结点，则表示创建该结点的会话的SessionID；如果是持久结点，该属性值为0
• dataLength：当前节点的数据内容长度
• numChildren：当前数据结点的子结点个数

help命令

zookeeper基本常用命令通过help查看，遇到错误命令可以直接查询语法。

ZooKeeper -server host:port cmd args
 addauth scheme auth
 close 
 config [-c] [-w] [-s]
 connect host:port
 create [-s] [-e] [-c] [-t ttl] path [data] [acl]
 delete [-v version] path
 deleteall path
 delquota [-n|-b] path
 get [-s] [-w] path
 getAcl [-s] path
 history 
 listquota path
 ls [-s] [-w] [-R] path
 ls2 path [watch]
 printwatches on|off
 quit 
 reconfig [-s] [-v version] [[-file path] | [-members serverID=host:port1:port2;port3[,...]*]] | [-add serverId=host:port1:port2;port3[,...]]* [-remove serverId[,...]*]
 redo cmdno
 removewatches path [-c|-d|-a] [-l]
 rmr path
 set [-s] [-v version] path data
 setAcl [-s] [-v version] [-R] path acl
 setquota -n|-b val path
 stat [-w] path
 sync path
Command not found: Command not found help

新增、查询节点

新增命令：create [-s] [-e] path data

其中 -s 为有序结点，-e 临时结点（默认是持久结点）

• -s 查看节点所有信息:数据信息+节点属性值
• -w 查看节点数据信息

实战

//创建持久化节点node1
[zk: localhost:2181(CONNECTED) 0] create /node1 "123"
Created /node1
//查看node1节点属性
[zk: localhost:2181(CONNECTED) 1] get -s /node1
123
cZxid = 0x43
ctime = Wed Jul 29 21:27:31 CST 2020
mZxid = 0x43
mtime = Wed Jul 29 21:27:31 CST 2020
pZxid = 0x43
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 3
numChildren = 0
//创建有序持久化节点
[zk: localhost:2181(CONNECTED) 2] create -s /seqNode1 "seq1"
Created /seqNode10000000011
//查看有序持久化节点信息
[zk: localhost:2181(CONNECTED) 3] get -s /seqNode10000000011
seq1
cZxid = 0x44
ctime = Wed Jul 29 21:28:25 CST 2020
mZxid = 0x44
mtime = Wed Jul 29 21:28:25 CST 2020
pZxid = 0x44
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 4
numChildren = 0
//创建临时节点
[zk: localhost:2181(CONNECTED) 4] create -s -e /tmpNode1 "tmp"
Created /tmpNode10000000012
[zk: localhost:2181(CONNECTED) 5] get -s /tmpNode10000000012
tmp
cZxid = 0x45
ctime = Wed Jul 29 21:35:28 CST 2020
mZxid = 0x45
mtime = Wed Jul 29 21:35:28 CST 2020
pZxid = 0x45
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x10029ab39130008
dataLength = 3
numChildren = 0

修改节点

-v + 版本号，类似乐观锁原理；

[zk: localhost:2181(CONNECTED) 13] set /node1 "456"
[zk: localhost:2181(CONNECTED) 14] get -w /node1
456
[zk: localhost:2181(CONNECTED) 15] set -v 0 /node1 "234"

WATCHER::

WatchedEvent state:SyncConnected type:NodeDataChanged path:/node1
[zk: localhost:2181(CONNECTED) 16] get -w /node1
234

删除节点

命令：delete [-v version] path:可以直接删除，也可以指定版本号删除，此命令只能删除单个节点，如果存在子节点，则需要依次删除子节点

deleteall path：直接删除指定的所有节点

[zk: localhost:2181(CONNECTED) 0] delete /node1
[zk: localhost:2181(CONNECTED) 1] get -s /node1
org.apache.zookeeper.KeeperException$NoNodeException: KeeperErrorCode = NoNode for /node1
[zk: localhost:2181(CONNECTED) 4] create /node1 "node1"
Created /node1
[zk: localhost:2181(CONNECTED) 5] create /node1/node11 "node11"
Created /node1/node11
//使用delete删除存在子节点的节点，删除失败
[zk: localhost:2181(CONNECTED) 6] delete /node1
Node not empty: /node1
[zk: localhost:2181(CONNECTED) 7] get -s /node1
node1
cZxid = 0x4f
ctime = Wed Jul 29 21:53:37 CST 2020
mZxid = 0x4f
mtime = Wed Jul 29 21:53:37 CST 2020
pZxid = 0x50
cversion = 1
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 5
numChildren = 1
[zk: localhost:2181(CONNECTED) 8] deleteall /node1
[zk: localhost:2181(CONNECTED) 9] get /node1
org.apache.zookeeper.KeeperException$NoNodeException: KeeperErrorCode = NoNode for /node1

注意：删除存在子节点时，命令不要再使用rmr，此命令已经无效。

[zk: localhost:2181(CONNECTED) 17] rmr /node1
The command 'rmr' has been deprecated. Please use 'deleteall' instead.

查看子节点列表

命令：

ls [-s] [-w] [-R] path:

ls2 path [watch]

[zk: localhost:2181(CONNECTED) 19] ls /
[a0000000001, b0000000002, c, hadoop, seqNode10000000011, zookeeper]
[zk: localhost:2181(CONNECTED) 20] ls -s /
[a0000000001, b0000000002, c, hadoop, seqNode10000000011, zookeeper]cZxid = 0x0
ctime = Thu Jan 01 08:00:00 CST 1970
mZxid = 0x0
mtime = Thu Jan 01 08:00:00 CST 1970
pZxid = 0x53
cversion = 22
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 0
numChildren = 6

[zk: localhost:2181(CONNECTED) 21] create /node1 "node1"
Created /node1
//当前节点下没有子节点，返回空数组
[zk: localhost:2181(CONNECTED) 22] ls /node1
[]
[zk: localhost:2181(CONNECTED) 23] create /node1/node11 "node11"
Created /node1/node11
[zk: localhost:2181(CONNECTED) 24] ls /node1
[node11]

查看节点状态

使用stat命令查看节点状态，与get命令的区别是此命令不返回数据信息；

[zk: localhost:2181(CONNECTED) 25] stat /node1
cZxid = 0x55
ctime = Wed Jul 29 22:05:16 CST 2020
mZxid = 0x55
mtime = Wed Jul 29 22:05:16 CST 2020
pZxid = 0x56
cversion = 1
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 5
numChildren = 1

监听器

[zk: localhost:2181(CONNECTED) 27] get /node1 watch
'get path [watch]' has been deprecated. Please use 'get [-s] [-w] path' instead.
node1

使用 get [-s] [-w] path注册的监听器能够在结点内容发生改变的时候，向客户端发出通知。需要注意的是zookeeper的触发器是一次性的(One-time trigger)，即触发一次后就会立即失效。

//一个窗口监听，新打开一个窗口修改节点数据
[zk: localhost:2181(CONNECTED) 29] get -w /node1
node1
//收到修改信息
[zk: localhost:2181(CONNECTED) 30] 
WATCHER::

WatchedEvent state:SyncConnected type:NodeDataChanged path:/node1

//另一个窗口修改节点：
[zk: localhost:2181(CONNECTED) 0] set /node1 "set node1"

权限控制

zookeeper类似文件系统，client可以创建结点、更新结点、删除结点，那么如何做到结点的权限控制呢？

zookeeper的 access control list 访问控制列表可以做到这一点。

acl权限控制，使用scheme：id：permission来标识，主要涵盖3个方面：

• 权限模式(scheme)：授权的策略
• 授权对象(id)：授权的对象
• 权限(permission)：授予的权限

权限模式

授权对象

• 给谁授予权限
• 授权对象ID是指，权限赋予的实体，例如：IP地址或用户

权限

create、delete、read、writer、admin也就是 增、删、查、改、管理权限，这5种权限简写为 c d r w a，注意：这五种权限中，有的权限并不是对结点自身操作的例如：delete是指对子结点的删除权限。

可以试图删除父结点，但是子结点必须删除干净，所以delete的权限也是很有用的

授权的相关命令

world模式:

[zk: localhost:2181(CONNECTED) 31] getAcl /node1
'world,'anyone
: cdrwa
[zk: localhost:2181(CONNECTED) 32] setAcl /node1 world:anyone:drwa
[zk: localhost:2181(CONNECTED) 33] create /node1/node2 "node2"
Authentication is not valid : /node1/node2
[zk: localhost:2181(CONNECTED) 34] setAcl /node1 world:anyone:cdrwa
[zk: localhost:2181(CONNECTED) 35] create /node1/node2 "node2"
Created /node1/node2

IP模式：

需要两台虚拟机一起授权的话需要用逗号将授权列表隔开：setAcl /ipNode ip:192.168.103.133:cdrwa,ip:192.168.103.132:cdrwa

[zk: localhost:2181(CONNECTED) 8] create /ipNode "ipNode"
Created /ipNode
[zk: localhost:2181(CONNECTED) 9] get -s /ipNode
ipNode
cZxid = 0x65
ctime = Wed Jul 29 23:22:23 CST 2020
mZxid = 0x65
mtime = Wed Jul 29 23:22:23 CST 2020
pZxid = 0x65
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 6
numChildren = 0
[zk: localhost:2181(CONNECTED) 10] setAcl /ipNode ip:192.168.16.81:ra
[zk: localhost:2181(CONNECTED) 11] get -s /ipNode
org.apache.zookeeper.KeeperException$NoAuthException: KeeperErrorCode = NoAuth for /ipNode

auth模式：

命令：

addauth digest <user>:<password>

setAcl <path> auth:<user>:<acl>

//认证用户
[zk: localhost:2181(CONNECTED) 36] addauth digest qxy:123456
[zk: localhost:2181(CONNECTED) 37] get -s /node1
set node1
cZxid = 0x55
ctime = Wed Jul 29 22:05:16 CST 2020
mZxid = 0x58
mtime = Wed Jul 29 22:31:29 CST 2020
pZxid = 0x5c
cversion = 2
dataVersion = 1
aclVersion = 2
ephemeralOwner = 0x0
dataLength = 9
numChildren = 2
//设置认证用户
[zk: localhost:2181(CONNECTED) 38] setAcl /node1 auth:qxy:cdrwa
//退出，重新进入
[zk: localhost:2181(CONNECTED) 39] quit

WATCHER::

WatchedEvent state:Closed type:None path:null
2020-07-29 22:58:56,574 [myid:] - INFO  [main:ZooKeeper@1422] - Session: 0x10029ab39130009 closed
2020-07-29 22:58:56,574 [myid:] - INFO  [main-EventThread:ClientCnxn$EventThread@524] - EventThread shut down for session: 0x10029ab39130009
//未用户认证，无法获取节点信息
[zk: localhost:2181(CONNECTED) 0] get -s /node1
org.apache.zookeeper.KeeperException$NoAuthException: KeeperErrorCode = NoAuth for /node1
//认证用户，注意此处密码错误，不会提示错误，但是无法访问节点
[zk: localhost:2181(CONNECTED) 1] addauth digest qxy:123456
[zk: localhost:2181(CONNECTED) 2] get -s /node1
set node1
cZxid = 0x55
ctime = Wed Jul 29 22:05:16 CST 2020
mZxid = 0x58
mtime = Wed Jul 29 22:31:29 CST 2020
pZxid = 0x5c
cversion = 2
dataVersion = 1
aclVersion = 3
ephemeralOwner = 0x0
dataLength = 9
numChildren = 2

Digest模式：

命令：setAcl <path> digest:<user>:<password>:<acl>

密码是经过SHA1以及BASE64处理的密文，在shell 中可以通过以下命令计算：

 echo -n <user>:<password> | openssl dgst -binary -sha1 | openssl base64

建立新的窗口，计算密码

[root@izbp14najjyuhkvm4qbic7z bin]# echo -n qxy:123456 | openssl dgst -binary -sha1 | openssl base64
hDF4uLZvMJqOX2ekKFa6kSz9HNo=

实战：

[zk: localhost:2181(CONNECTED) 5] create /digestNode "digestNode"
Created /digestNode
[zk: localhost:2181(CONNECTED) 2] setAcl /digestNode digest:qxy:hDF4uLZvMJqOX2ekKFa6kSz9HNo=:cdrwa
[zk: localhost:2181(CONNECTED) 3] get /digestNode
org.apache.zookeeper.KeeperException$NoAuthException: KeeperErrorCode = NoAuth for /digestNode
[zk: localhost:2181(CONNECTED) 2] setAcl /digestNode digest:qxy:hDF4uLZvMJqOX2ekKFa6kSz9HNo=:cdrwa
[zk: localhost:2181(CONNECTED) 3] get /digestNode
org.apache.zookeeper.KeeperException$NoAuthException: KeeperErrorCode = NoAuth for /digestNode
[zk: localhost:2181(CONNECTED) 4] getAcl /digestNode
Authentication is not valid : /digestNode
[zk: localhost:2181(CONNECTED) 5] addauth digest qxy:123456
[zk: localhost:2181(CONNECTED) 6] getAcl /digestNode
'digest,'qxy:hDF4uLZvMJqOX2ekKFa6kSz9HNo=
: cdrwa
[zk: localhost:2181(CONNECTED) 7] get /digestNode
digestNode

来源：blog.csdn.net/xuan_lu/article/details/107675047

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