Zookeeper notes

1. Cluster roles and division of labor

• Leader leaders

  The leader node in the cluster.Copy the code

• Flower follower

  Followers participate in elections and data synchronization.Copy the code

• The observer observers

  Observer nodes have business data but do not participate in elections. Thus, data synchronization and election efficiency can be ensured.Copy the code

2. Common commands

• Starting a Service Node

  ./zkServer.sh start .. /conf/zoo.cfgCopy the code

• Viewing node Status (Primary/Secondary)

  ./zkServer.sh status
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• Start the client connection

  . / zkCli. Sh - server 127.0.0.1:2181Copy the code

• List the nodes

  ls /
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• Create a node

  create /test 'content'
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• Create temporary nodes (children cannot be created under temporary nodes)

  create -e /test-e 'content'
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• Creating sequence nodes

  Create -s/TEST_SEq_ 1 The result shows: Created/TEST_SEq_0000000001Copy the code

• Obtaining node content

  get /test
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• Viewing Node Information

  Stat /test: Ctime = Mon Apr 26 12:28:29 CST 2021 mZxid = 0x8b mtime = Mon Apr 26 12:28:29 CST 2021 # Time of node change pZxid = 0x8B # Transaction ID of node increase, Delete, change Cversion = 0 # Number of changes on this node datLVersion = 0 # Number of changes on this node data EphemeralOwner = 0x0 # The value is 0 or the sessionID of the temporary node dataLength = 1 # The length of the data on the node numChildren = 0 # The number of child nodesCopy the code

• Remove nodes

  Delete /test # Delete current node RMR /test # Cascade delete nodeCopy the code

• Viewing Node Rights

  GetAcl /test results show :' World,'anyone: Cdrwa ACL permission control, identified by Schmea: ID: Permission, mainly covers three aspects: - Permission Schema: authentication policy - Authorization object (ID) - Permission schema. world: only one user; Anyone represents everyone (default). IP: authenticate with an IP address. Auth: authenticate with an authenticated user. Use "Username: DELETE d can DELETE the child node. READ R can READ the node data. WRITE W can set the node data. You can set access control lists for nodesCopy the code

• Add user

  addauth digest zhangsan:123456  
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3. The other

• The maximum size of each node is 1 MB by default

• A child node does not inherit the permissions of its parent node. A client may not have access to a node, but can access its children.

• Zookeeper native client listeners can only listen to new ZooKeeper () once.

• The operations that can register listeners are getData(),

• Use the ZkClient client

4. Set up a cluster

Prepare three VMS. Node1 IP 192.168.108.13 Node2 IP 192.168.108.11 Node3 IP 192.168.108.8 2. Download ZooKeeper 3 from the Apache website. CFG file and name it zoo_sample. CFG 4. Modify the dataDir path. 5. Create the myID file 6 in the dataDir path. CFG file. Server. 1=192.168.108.13:2888:3888 server.2=192.168.108.11:2888:3888 server.3=192.168.108.8:2888:3888 Ps: Enter the server IP address. Unable to read Additional data from server sessionID 0x0, likely Server has closed socket, closing socket connection and attempting reconnectCopy the code