Install Apache ZooKeeper on Ubuntu

What ZooKeeper is

Apache ZooKeeper is a service that keeps configuration and naming data, and helps distributed systems such as Kafka and Hadoop to coordinate.

Step 1: Install Java

Check if Java is installed:

java --version

If not, install it:

sudo apt update
sudo apt install default-jdk

Step 2: Create a user for ZooKeeper

sudo adduser --system --group --home /opt/zookeeper zookeeper

Step 3: Create the data folder

sudo mkdir -p /var/lib/zookeeper
sudo chown zookeeper:zookeeper /var/lib/zookeeper

Step 4: Download and install ZooKeeper

cd /opt

Open the Apache ZooKeeper download page and copy the link of the latest stable binary release.

Download it (replace the version with the current one):

sudo wget https://dlcdn.apache.org/zookeeper/zookeeper-3.9.2/apache-zookeeper-3.9.2-bin.tar.gz

Extract it:

sudo tar -xzf apache-zookeeper-*.tar.gz -C /opt

Rename the folder:

sudo mv /opt/apache-zookeeper-*-bin /opt/zookeeper

Give the user the right to own it:

sudo chown -R zookeeper:zookeeper /opt/zookeeper

Step 5: Configure ZooKeeper

Copy the sample file to zoo.cfg:

sudo cp /opt/zookeeper/conf/zoo_sample.cfg /opt/zookeeper/conf/zoo.cfg
sudo nano /opt/zookeeper/conf/zoo.cfg

Use these settings:

tickTime=2000
dataDir=/var/lib/zookeeper
clientPort=2181
initLimit=10
syncLimit=5

• tickTime. The basic time unit in milliseconds.
• dataDir. Where ZooKeeper keeps its data.
• clientPort. The port for client connections.
• initLimit. The time that followers have to connect and sync to the leader.
• syncLimit. The time allowed between a request and its acknowledgment.

Step 6: Create a system service

sudo nano /etc/systemd/system/zookeeper.service

Add:

[Unit]
Description=Apache ZooKeeper Service
After=network.target

[Service]
Type=forking
User=zookeeper
Group=zookeeper
ExecStart=/opt/zookeeper/bin/zkServer.sh start
ExecStop=/opt/zookeeper/bin/zkServer.sh stop
Restart=on-failure

[Install]
WantedBy=multi-user.target

Reload systemd:

sudo systemctl daemon-reload

Step 7: Start ZooKeeper

sudo systemctl start zookeeper
sudo systemctl enable zookeeper
sudo systemctl status zookeeper

Test with the client:

/opt/zookeeper/bin/zkCli.sh -server 127.0.0.1:2181

Quick recap

• Install Java, create a user, download and extract ZooKeeper.
• Set zoo.cfg with dataDir and clientPort.
• Run it as a systemd service.