Side Notes

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Simple Zookeeper Cluster

Sometimes I need to run ZooKeeper ensemble on my development box to test my application on the production-like environment. I found that recreating the whole ensemble from scratch is much faster than cleaning it up using ZooKeeper CLI tool. To automate this process I created a bash script which I want to share in this blog post. I hard-coded all the paths in the script using my regular conventions. You might need to change them to yours — it should be fairly straightforward.

Before you can use the script, you need to install ZooKeeper on your box. That’s what I did on my machine

$ cd /opt
$ sudo mkdir zookeeper
$ sudo chown -R andrey:admin zookeeper
$ cd zookeeper
$ wget http://apache.mirror.rafal.ca/zookeeper/zookeeper-3.4.5/zookeeper-3.4.5.tar.gz
$ tar xf zookeeper-3.4.5.tar.gz
$ rm zookeeper-3.4.5.tar.gz
$ ln -s zookeeper-3.4.5 zookeeper

In the end you should have a ZooKeeper installed in /opt/zookeeper/zookeeper directory.

Now download, chmod, and run the script. It will create the following files

/opt/zookeeper/zookeeper/cluster
├── server1
│   ├── conf
│   │   ├── log4j.properties
│   │   └── zoo.cfg
│   ├── data
│   │   └── myid
│   └── logs
├── server2
│   ├── conf
│   │   ├── log4j.properties
│   │   └── zoo.cfg
│   ├── data
│   │   └── myid
│   └── logs
├── server3
│   ├── conf
│   │   ├── log4j.properties
│   │   └── zoo.cfg
│   ├── data
│   │   └── myid
│   └── logs
├── start.sh
└── stop.sh

This is the minimum configuration for 3-node ensemble (cluster), which is recommended for production. To start the cluster, run the following command

$ cd /opt/zookeeper/zookeeper
$ cluster/start.sh

Check the log files to see if the cluster is successfully started

$ tail -f cluster/server{1,2,3}/logs/zookeeper.out

When the cluster is up and running, you can test your application. After you are done, shutdown the cluster using the following command

$ cluster/stop.sh
$ ps -ef | grep java

To recreate a clean cluster, just run the script again

$ ./zookeeper-init-ensemble.sh