Using Zookeeper | Configuration Management

Introduction to Zookeeper

Apache Zookeeper is an open-source distributed coordination service that helps manage configuration information, naming, synchronization, and group services across distributed systems. It is widely used to maintain configuration consistency and to provide distributed synchronization.

Installing Zookeeper

To get started with Zookeeper, you need to install it on your Linux system. Follow these steps to install Zookeeper using a package manager:

sudo apt-get update

sudo apt-get install zookeeperd

After installation, you can start the Zookeeper service using the following command:

sudo service zookeeper start

Configuring Zookeeper

The main configuration file for Zookeeper is located at /etc/zookeeper/conf/zoo.cfg. Here, you can set various parameters like data directory, client port, and tick time.

For example, to set the data directory and client port, you can edit the zoo.cfg file as follows:

dataDir=/var/lib/zookeeper

clientPort=2181

Starting and Stopping Zookeeper

You can manage the Zookeeper service by using the following commands:

To start Zookeeper:

sudo service zookeeper start

To stop Zookeeper:

sudo service zookeeper stop

To restart Zookeeper:

sudo service zookeeper restart

Interacting with Zookeeper

Once Zookeeper is up and running, you can interact with it using the Zookeeper CLI. To start the CLI, use the following command:

zkCli.sh

Here are some basic commands you can use in the Zookeeper CLI:

To create a znode:

create /my_znode "my_data"

To get data from a znode:

get /my_znode

To set data for a znode:

set /my_znode "new_data"

To delete a znode:

delete /my_znode

Monitoring Zookeeper

Monitoring Zookeeper is crucial to ensure it is running smoothly. You can use the following command to check the status of the Zookeeper service:

sudo service zookeeper status

Additionally, Zookeeper provides a set of four-letter commands that can be used to check the health and status of the Zookeeper ensemble. Here are a few examples:

To check the status of the server:

echo "stat" | nc localhost 2181

To check the server's mode (leader/follower):

echo "srvr" | nc localhost 2181

Conclusion

In this tutorial, we covered the basics of using Zookeeper for configuration management. We installed and configured Zookeeper, learned how to start and stop the service, interacted with it using the CLI, and explored some monitoring techniques. Zookeeper is a powerful tool that can help manage distributed systems with ease.

Using Zookeeper for Configuration Management