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Last pushed: 2 months ago
Short Description
ZooKeeper is a centralized service for distributed applications.
Full Description



What is zookeeper?

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

version: '2'

services:
  zookeeper:
    image: 'bitnami/zookeeper:latest'
    ports:
      - '2181:2181'

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.

Note!
If you have already started using Zookeeper, follow the steps on
backing up and restoring to pull the data from your running container down to your host.

The image exposes a volume at /bitnami/zookeeper for the Zookeeper data and configurations. For persistence you can mount a directory at this location from your host. If the mounted directory is empty, it will be initialized on the first run.

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

or using Docker Compose:

version: '2'

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

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:

  1. Please update the YOUR_APPLICATION_IMAGE placeholder in the above snippet with your application image
  2. 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.
  • ZOO_CLIENT_USER: User that will use Zookeeper clients to auth. Default: No defaults.
  • ZOO_CLIENT_PASSWORD: Password that will use Zookeeper clients to auth. No defaults.
  • ZOO_SERVER_USERS: Comma, semicolon or whitespace separated list of user to be created. Example: user1,user2,admin. No defaults
  • ZOO_SERVER_PASSWORDS: Comma, semicolo or whitespace separated list of passwords to assign to users when created. Example: pass4user1, pass4user2, pass4admin. No defaults
  • ZOO_ENABLE_AUTH: Enable Zookeeper auth. It uses SASL/Digest-MD5. Default: no
  • ALLOW_ANONYMOUS_LOGIN: If set to true, Allow to accept connections from unauthenticated users. Default: no
  • JVMFLAGS: Default JVMFLAGS for the ZooKeeper process. Default: -Xmx1024m -Xms1024m
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

The image looks for configuration in the conf/ directory of /bitnami/zookeeper.

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

or using Docker Compose:

version: '2'

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

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

Security

Authentication based on SASL/Digest-MD5 can be easily enabled by passing the ZOO_ENABLE_AUTH env var.
When enabling the ZooKeeper authentication, it is also required to pass the list of users and passwords that will
be able to login.

docker run -it -e ZOO_ENABLE_AUTH=yes \
               -e ZOO_SERVER_USERS=user1,user2 \
               -e ZOO_SERVER_PASSWORDS=pass4user1,pass4user2 \
               bitnami/zookeeper

or using Docker Compose:

version: '2'

services:
  zookeeper:
    image: 'bitnami/zookeeper:latest'
    ports:
      - '2181:2181'
    environment:
      - ZOO_ENABLE_AUTH=yes
      - ZOO_SERVER_USERS=user1,user2
      - ZOO_SERVER_PASSWORDS=pass4user1,pass4user2

Setting up a Zookeeper ensemble

A Zookeeper (https://zookeeper.apache.org/doc/r3.1.2/zookeeperAdmin.html) cluster can easily be setup with the Bitnami Zookeeper Docker image using the following environment variables:

  • ZOO_SERVERS: Comma or colon separated list of servers. Example: server.1=zoo1:2888:3888,server.2=zoo2:2888:3888. No defaults.

For reliable ZooKeeper service, you should deploy ZooKeeper in a cluster known as an ensemble. As long as a majority of the ensemble are up, the service will be available. Because Zookeeper requires a majority, it is best to use an odd number of machines. For example, with four machines ZooKeeper can only handle the failure of a single machine; if two machines fail, the remaining two machines do not constitute a majority. However, with five machines ZooKeeper can handle the failure of two machines.

You have to use 0.0.0.0 as the host for the server. More concretely, if the ID of the zookeeper1 container starting is 1, then the ZOO_SERVERS environment variable has to be server.1=0.0.0.0:2888:3888,server.2=zookeeper2:2888:3888.server3=zookeeper3:2888:3888. See below:

Create a Docker network to enable visibility to each other via the docker container name

docker network create app-tier --driver bridge

Step 1: Create the first node

The first step is to create one Zookeeper instance.

docker run --name zookeeper1 \
  --network app-tier \
  -e ZOO_SERVER_ID=1 \
  -e ZOO_SERVERS=server.1=0.0.0.0:2888:3888,server.2=zookeeper2:2888:3888,server.3=zookeeper3:2888:3888 \
  -p 2181:2181 \
  -p 2888:2888 \
  -p 3888:3888 \
  bitnami/zookeeper:latest

Step 2: Create the second node

Next we start a new Zookeeper container.

docker run --name zookeeper2 \
  --network app-tier \
  -e ZOO_SERVER_ID=2 \
  -e ZOO_SERVERS=server.1=zookeeper1:2888:3888,server.2=0.0.0.0:2888:3888,server.3=zookeeper3:2888:3888 \
  -p 2181:2181 \
  -p 2888:2888 \
  -p 3888:3888 \
  bitnami/zookeeper:latest

Step 3: Create the third node

Next we start another new Zookeeper container.

docker run --name zookeeper3 \
  --network app-tier \
  -e ZOO_SERVER_ID=3 \
  -e ZOO_SERVERS=server.1=zookeeper1:2888:3888,server.2=zookeeper2:2888:3888,server.3=0.0.0.0:2888:3888 \
  -p 2181:2181 \
  -p 2888:2888 \
  -p 3888:3888 \
  bitnami/zookeeper:latest

You now have a two node Zookeeper cluster up and running. You can scale the cluster by adding/removing slaves without incurring any downtime.

With Docker Compose the ensemble can be setup using:

version: '2'

services:
  zookeeper1:
    image: 'bitnami/zookeeper:latest'
    ports:
      - '2181'
      - '2888'
      - '3888'
    volumes:
      - /path/to/zookeeper-persistence:/bitnami/zookeeper
    environment:
      - ZOO_SERVER_ID=1
      - ZOO_SERVERS=server.1=0.0.0.0:2888:3888,server.2=zookeeper2:2888:3888,server.3=zookeeper3:2888:3888
  zookeeper2:
    image: 'bitnami/zookeeper:latest'
    ports:
      - '2181'
      - '2888'
      - '3888'
    volumes:
      - /path/to/zookeeper-persistence:/bitnami/zookeeper
    environment:
      - ZOO_SERVER_ID=2
      - ZOO_SERVERS=server.1=zookeeper1:2888:3888,server.2=0.0.0.0:2888:3888,server.3=zookeeper3:2888:3888
  zookeeper3:
    image: 'bitnami/zookeeper:latest'
    ports:
      - '2181'
      - '2888'
      - '3888'
    volumes:
      - /path/to/zookeeper-persistence:/bitnami/zookeeper
    environment:
      - ZOO_SERVER_ID=3
      - ZOO_SERVERS=server.1=zookeeper1:2888:3888,server.2=zookeeper2:2888:3888,server.3=0.0.0.0:2888:3888

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

Backing up your container

To backup your data, configuration and logs, follow these simple steps:

Step 1: Stop the currently running container

docker stop zookeeper

or using Docker Compose:

docker-compose stop zookeeper

Step 2: Run the backup command

We need to mount two volumes in a container we will use to create the backup: a directory on your host to store the backup in, and the volumes from the container we just stopped so we can access the data.

docker run --rm -v /path/to/zookeeper-backups:/backups --volumes-from zookeeper busybox \
  cp -a /bitnami/zookeeper:latest /backups/latest

or using Docker Compose:

docker run --rm -v /path/to/zookeeper-backups:/backups --volumes-from `docker-compose ps -q zookeeper` busybox \
  cp -a /bitnami/zookeeper:latest /backups/latest

Restoring a backup

Restoring a backup is as simple as mounting the backup as volumes in the container.

docker run -v /path/to/zookeeper-backups/latest:/bitnami/zookeeper bitnami/zookeeper:latest

or using Docker Compose:

version: '2'

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

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

Before continuing, you should backup your container's data, configuration and logs.

Follow the steps on creating a backup.

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, restoring your backup if necessary.

docker run --name zookeeper bitnami/zookeeper:latest

or using Docker Compose:

docker-compose start zookeeper

Notable Changes

3.4.10-r4

  • The zookeeper container has been migrated to a non-root container approach. Previously the container run as root user and the zookeeper daemon was started as zookeeper user. From now own, both the container and the zookeeper daemon run as user 1001.
    As a consequence, the configuration files are writable by the user running the zookeeper process.

3.4.10-r0

  • New release

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

Copyright (c) 2015-2017 Bitnami

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.

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