ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services. All of these kinds of services are used in some form or other by distributed applications.

https://zookeeper.apache.org/

TL;DR;

$ docker run --name zookeeper bitnami/zookeeper:latest

Docker Compose

$ curl -sSL https://raw.githubusercontent.com/bitnami/bitnami-docker-zookeeper/master/docker-compose.yml > docker-compose.yml
$ docker-compose up -d

Kubernetes

WARNING: This is a beta configuration, currently unsupported.

Get the raw URL pointing to the kubernetes.yml manifest and use kubectl to create the resources on your Kubernetes cluster like so:

$ kubectl create -f https://raw.githubusercontent.com/bitnami/bitnami-docker-zookeeper/master/kubernetes.yml

Why use Bitnami Images?

Bitnami closely tracks upstream source changes and promptly publishes new versions of this image using our automated systems.
With Bitnami images the latest bug fixes and features are available as soon as possible.
Bitnami containers, virtual machines and cloud images use the same components and configuration approach - making it easy to switch between formats based on your project needs.
Bitnami images are built on CircleCI and automatically pushed to the Docker Hub.
All our images are based on minideb a minimalist Debian based container image which gives you a small base container image and the familiarity of a leading linux distribution.

Get this image

The recommended way to get the Bitnami Zookeeper Docker Image is to pull the prebuilt image from the Docker Hub Registry.

$ docker pull bitnami/zookeeper:latest

To use a specific version, you can pull a versioned tag. You can view the list of available versions in the Docker Hub Registry.

$ docker pull bitnami/zookeeper:[TAG]

If you wish, you can also build the image yourself.

$ docker build -t bitnami/zookeeper:latest https://github.com/bitnami/bitnami-docker-zookeeper.git

Persisting your data

If you remove the container all your data and configurations will be lost, and the next time you run the image the database will be reinitialized. To avoid this loss of data, you should mount a volume that will persist even after the container is removed.

For persistence you should mount a directory at the /bitnami path. If the mounted directory is empty, it will be initialized on the first run.

$ docker run \
  -v /path/to/zookeeper-persistence:/bitnami \
  bitnami/zookeeper:latest

or using Docker Compose:

version: '2'

services:
  zookeeper:
    image: 'bitnami/zookeeper:latest'
    ports:
      - '2181:2181'
    volumes:
      - /path/to/zookeeper-persistence:/bitnami

Connecting to other containers

Using Docker container networking, a Zookeeper server running inside a container can easily be accessed by your application containers.

Containers attached to the same network can communicate with each other using the container name as the hostname.

Using the Command Line

In this example, we will create a Zookeeper client instance that will connect to the server instance that is running on the same docker network as the client.

Step 1: Create a network

$ docker network create app-tier --driver bridge

Step 2: Launch the Zookeeper server instance

Use the --network app-tier argument to the docker run command to attach the Zookeeper container to the app-tier network.

$ docker run -d --name zookeeper-server \
    --network app-tier \
    bitnami/zookeeper:latest

Step 3: Launch your Zookeeper client instance

Finally we create a new container instance to launch the Zookeeper client and connect to the server created in the previous step:

$ docker run -it --rm \
    --network app-tier \
    bitnami/zookeeper:latest zkCli.sh -server zookeeper-server:2181  get /

Using Docker Compose

When not specified, Docker Compose automatically sets up a new network and attaches all deployed services to that network. However, we will explicitly define a new bridge network named app-tier. In this example we assume that you want to connect to the Zookeeper server from your own custom application image which is identified in the following snippet by the service name myapp.

version: '2'

networks:
  app-tier:
    driver: bridge

services:
  zookeeper:
    image: 'bitnami/zookeeper:latest'
    networks:
      - app-tier
  myapp:
    image: 'YOUR_APPLICATION_IMAGE'
    networks:
      - app-tier

Important

:

Please update the YOUR_APPLICATION_IMAGE placeholder in the above snippet with your application image

In your application container, use the hostname zookeeper to connect to the Zookeeper server

Launch the containers using:

$ docker-compose up -d

Configuration

The configuration can easily be setup with the Bitnami Zookeeper Docker image using the following environment variables:

ZOO_PORT_NUMBER: Zookeeper client port. Default: 2181
ZOO_SERVER_ID: ID of the server in the ensemble. Default: 1
ZOO_TICK_TIME: Basic time unit in milliseconds used by ZooKeeper for heartbeats. Default: 2000
ZOO_INIT_LIMIT: ZooKeeper uses to limit the length of time the ZooKeeper servers in quorum have to connect to a leader. Default: 10
ZOO_SYNC_LIMIT: How far out of date a server can be from a leader. Default: 5
ZOO_SERVERS: Comma, space or colon separated list of servers. Example: server.1=zoo1:2888:3888,server.2=zoo2:2888:3888. No defaults.

$ docker run --name zookeeper -e ZOO_SERVER_ID=1 bitnami/zookeeper:latest

or using Docker Compose:

version: '2'

services:
  zookeeper:
    image: 'bitnami/zookeeper:latest'
    ports:
      - '2181:2181'
    environment:
      - ZOO_SERVER_ID=1

Configuration file

The image looks for configurations in /bitnami/zookeeper/conf/. As mentioned in Persisting your data you can mount a volume at /bitnami and copy/edit the configurations in the /path/to/zookeeper-persistence/zookeeper/conf/. The default configurations will be populated to the conf/ directory if it's empty.

$ docker run --name zookeeper \
    -v /path/to/my_custom_conf_directory:/bitnami \
    bitnami/zookeeper:latest

After that, your changes will be taken into account in the server's behaviour.

Step 1: Run the Zookeeper image

Run the Zookeeper image, mounting a directory from your host.

$ docker run --name zookeeper \
    -v /path/to/zookeeper-persistence:/bitnami \
    bitnami/zookeeper:latest

or using Docker Compose:

version: '2'

services:
  zookeeper:
    image: 'bitnami/zookeeper:latest'
    ports:
      - '2181:2181'
    volumes:
      - /path/to/zookeeper-persistence:/bitnami

Step 2: Edit the configuration

Edit the configuration on your host using your favorite editor.

$ vi /path/to/zookeeper-persistence/conf/zoo.cfg

Step 3: Restart Zookeeper

After changing the configuration, restart your Zookeeper container for changes to take effect.

$ docker restart zookeeper

or using Docker Compose:

$ docker-compose restart zookeeper

Logging

The Bitnami Zookeeper Docker image sends the container logs to the stdout. To view the logs:

$ docker logs zookeeper

or using Docker Compose:

$ docker-compose logs zookeeper

You can configure the containers logging driver using the --log-driver option if you wish to consume the container logs differently. In the default configuration docker uses the json-file driver.

Maintenance

Upgrade this image

Bitnami provides up-to-date versions of Zookeeper, including security patches, soon after they are made upstream. We recommend that you follow these steps to upgrade your container.

Step 1: Get the updated image

$ docker pull bitnami/zookeeper:latest

or if you're using Docker Compose, update the value of the image property to bitnami/zookeeper:latest.

Step 2: Stop and backup the currently running container

Stop the currently running container using the command

$ docker stop zookeeper

or using Docker Compose:

$ docker-compose stop zookeeper

Next, take a snapshot of the persistent volume /path/to/zookeeper-persistence using:

$ rsync -a /path/to/zookeeper-persistence /path/to/zookeeper-persistence.bkp.$(date +%Y%m%d-%H.%M.%S)

You can use this snapshot to restore the database state should the upgrade fail.

Step 3: Remove the currently running container

$ docker rm -v zookeeper

or using Docker Compose:

$ docker-compose rm -v zookeeper

Step 4: Run the new image

Re-create your container from the new image.

$ docker run --name zookeeper bitnami/zookeeper:latest

or using Docker Compose:

$ docker-compose start zookeeper

Contributing

We'd love for you to contribute to this container. You can request new features by creating an issue, or submit a pull request with your contribution.

Issues

If you encountered a problem running this container, you can file an issue. For us to provide better support, be sure to include the following information in your issue:

Host OS and version
Docker version (docker version)
Output of docker info
Version of this container (echo $BITNAMI_IMAGE_VERSION inside the container)
The command you used to run the container, and any relevant output you saw (masking any sensitive information)

Community

Most real time communication happens in the #containers channel at bitnami-oss.slack.com; you can sign up at slack.oss.bitnami.com.

Discussions are archived at bitnami-oss.slackarchive.io.

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.