This Dockerfile creates a Docker image that can be used as the base for running ZooKeeper within a Docker container. The run script is responsible for creating the ZooKeeper configuration based on the container's environment and starting the ZooKeeper service.

The version of ZooKeeper is defined in the Dockerfile and generally points to the latest stable release of ZooKeeper.

The following environment variables are understood by the startup script to seed the service's configuration:

• SERVICE_NAME should contain the logical name of the service this container is an instance of;
• CONTAINER_NAME should contain the logical name of the container, which will be used for looking up links and ports informations from the other environment variables. For this, the name is uppercased and non-alphanumeric characters are replaced by underscores.
• <SERVICE_NAME>_<CONTAINER_NAME>_CLIENT_PORT, which controls the clientPort configuration setting. Defaults to 2181;
• <SERVICE_NAME>_<CONTAINER_NAME>_PEER_PORT, which is used as the peer port specified in the server list for this node (and the others). Defaults to 2888;
• <SERVICE_NAME>_<CONTAINER_NAME>_LEADER_ELECTION_PORT, which is used as the leader election port specified in the server list for this node (and the others). Defaults to 3888.

The ZooKeeper node ID, written out to the /var/lib/zookeeper/myid file, is infered from the position of this container's name in the list of all ZooKeeper nodes defined in the environment variables. Because these variables are always looked at in sorted order, this is deterministic as long as all ZooKeeper node containers start with the same set of <SERVICE_NAME>_* environment variables.

The ZooKeeper images uses the following volumes that you may want to bind from the container's host:

• /var/lib/zookeeper, for the ZooKeeper data snapshots.

To build a new image, simply run from this directory:

$ docker build -t `whoami`/zookeeper:3.4.5 .

The Docker image will be built and now available for Docker to start a new container from:

$ docker images | grep zookeeper
mpetazzoni/zookeeper   3.4.5              294bef30310b        2 days ago          12.29 kB (virtual 856.7 MB)