Confluent Platform ZooKeeper

This is a highly configurable Dockerized Apache ZooKeeper⁠ image which is part of the Confluent Platform⁠.

How to use this image

The container can be configured via environment variables where any ZooKeeper property can be set after zk_ with underscore instead of period ('.') used. For example:

A few sensible values have been set as given above.

The data directory, /var/lib/zookeeper, is exposed for mounting to your local host. This facilitates using external storage for data and snapshots and the transaction logs. The configuration directory, /etc/kafka, is also exposed for mounting such that you can use your own configuration file, zookeeper.properties, and also take advantage of variable substitution.

Using your configuration file

This image also provides for a remote properties file to be used, which will also be processed for variable substitution. To download a remote properties file, set the environment variable zk_cfg_url to the location of the file.

Standalone mode

If you are happy with the defaults, just run the container to get ZooKeeper in standalone mode:

docker run --rm --name zk -p 2181:2181 cgswong/confluent-zookeeper

Cluster mode

To run a cluster just set more zk_server_X environment variables, where X is the respective ZooKeeper ID, set to the respective IP/hostname. You'll also need to publish the respective cluster ports. For example:

docker run -d --name zk1 \
  -p 2181:2181 -p 2888:2888 -p 3888:3888 \
  -e zk_id=1 -e zk_server_1=172.17.8.101 -e zk_server_2=172.17.8.102 -e zk_server_3=172.17.8.103 \
  cgswong/confluent-zookeeper
docker run -d --name zk2 \
  --publish 2181:2181 --publish 2888:2888 --publish 3888:3888 \
  -e zk_id=2 -e zk_server_1=172.17.8.101 -e zk_server_2=172.17.8.102 -e zk_server_3=172.17.8.103 \
  cgswong/confluent-zookeeper
docker run -d --name zk3 \
  -p 2181:2181 -p 2888:2888 -p 3888:3888 \
  -e zk_id=3 -e zk_server_1=172.17.8.101 -e zk_server_2=172.17.8.102 -e zk_server_3=172.17.8.103 \
  cgswong/confluent-zookeeper

The above commands are run across 3 separate hosts. To form a cluster on a single host change the local port mappings to avoid collisions.

Acknowledgement

This image is a fork of the main ConfluentInc Platform⁠. As I do contribute back you may see some of these features included, however, some may not be included or take longer to be merged. I created this version not only to contribute back to a really good project, but also to learn, and have a version which was more robust (production ready since this is being used as such), with a more timely update cycle (for the time being anyways).