Installing ZooKeeper

1. Standalone Version

1.1. Download

• Apache ZooKeeper

1.2. Configuration

• conf/zoo.cfg

tickTime=2000
dataDir = /var/lib/zk
clientPort=2181

• Cluster configuration

tickTime=2000
dataDir = /var/lib/zk
clientPort=2181
initLimit=5
syncLimit=2
server.1=zoo1:2888:3888
server.1=zoo2:2888:3888
server.1=zoo3:2888:3888

1.3. Start

bin/zkServer.sh start

1.4. Operations

# Create a node
create /zk_test my_data
# Delete a node
delete /zk_test
# Recursively delete a node
rmr /zk_test
# List file nodes
ls /zk_test
# List file nodes and metadata
ls2 /zk_test
# View node status
stat /zk_test
# Get data from a node
get /zk_test
# Update a node
set /zk_test junk

# Watch node changes. Once the value changes, an event is triggered. It is triggered only once.
get -w /zk_test
# Watch node changes. Once child nodes change, an event is triggered. It is triggered only once.
ls -w /zk_test

# Help
help

1.4.1. Stat Structure

cZxid: the transaction ID of the change that caused the znode to be created.
mZxid: the transaction ID of the last change that modified the znode.
pZxid: the transaction ID of the znode change used to add or remove child nodes.
ctime: the znode creation time in milliseconds since 1970-01-01T00:00:00Z.
mtime: the znode’s most recent modification time in milliseconds since 1970-01-01T00:00:00Z.
dataVersion: the number of changes made to this znode’s data.
cversion: the number of changes made to the child nodes of this znode.
aclVersion: the number of changes made to this znode’s ACL.
ephemeralOwner: if the znode is an ephemeral node, this is the session ID of the znode owner. If the znode is not ephemeral, this field is set to zero.
dataLength: the length of the znode data field.
numChildren: the number of child nodes of the znode.

2. Cluster Version

2.1. Download

• Apache ZooKeeper

2.2. Configuration

2.2.1. Extract Three ZooKeeper Folders

2.2.2. Create the data Folders

mkdir -p zk1/data
mkdir -p zk2/data
mkdir -p zk3/data

2.2.3. Create myid

echo "1" > zk1/data/myid
echo "2" > zk2/data/myid
echo "3" > zk3/data/myid

2.2.4. Modify the Configuration Files

• zk1

tickTime=2000
initLimit=10
syncLimit=5
dataDir=<USER_HOME>/software/zks/zk1/data
clientPort=2181
server.1=127.0.0.1:2222:2223
server.2=127.0.0.1:3333:3334
server.3=127.0.0.1:4444:4445

• zk2

tickTime=2000
initLimit=10
syncLimit=5
dataDir=<USER_HOME>/software/zks/zk2/data
clientPort=2182
server.1=127.0.0.1:2222:2223
server.2=127.0.0.1:3333:3334
server.3=127.0.0.1:4444:4445

• zk3

tickTime=2000
initLimit=10
syncLimit=5
dataDir=<USER_HOME>/software/zks/zk3/data
clientPort=2183
server.1=127.0.0.1:2222:2223
server.2=127.0.0.1:3333:3334
server.3=127.0.0.1:4444:4445

2.3. Start

zk1/bin/zkServer.sh start
zk2/bin/zkServer.sh start
zk3/bin/zkServer.sh start

2.4. Operations

2.4.1. View Status

zk1/bin/zkServer.sh status //follower
zk2/bin/zkServer.sh status //leader
zk3/bin/zkServer.sh status //follower