The container can be configured via environment variables where any ZK property can be set after zk_ with underscore instead of period ('.') used. For example:
| Environment Variable | ZooKeeper Property | Default |
|---|---|---|
| zk_tickTime | tickTime | 5000 |
| zk_initLimit | initLimit | 5 |
| zk_syncLimit | syncLimit | 2 |
| zk_autopurge_snapRetainCount | autopurge.snapRetainCount | 3 |
| zk_autopurge_purgeInterval | autopurge.purgeInterval | 12 |
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 (/var/lib/zookeeper/data), and snapshots and the transaction logs (/var/lib/zookeeper/logs). The configuration directory, /opt/zookeeper/conf, is also exposed for mounting such that you can use your own configuration file, and also take advantage of variable substitution.
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.
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/zookeeperTo 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/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/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/zookeeperThe above commands are run across 3 separate hosts. To form a cluster on a single host change the local port mappings to avoid collisions.
If you have any problems with or questions about this image, please contact me through a GitHub issue.
You are invited to contribute new features, fixes, or updates, large or small; I'm always thrilled to receive pull requests, and I'll do my best to process them as fast as I can.
Before you start to code, I recommend discussing your plans through a GitHub issue, especially for more ambitious contributions. This gives other contributors a chance to point you in the right direction, give you feedback on your design, and help you find out if someone else is working on the same thing.