How to Install ZooKeeper

kc@example.com (kc kim) — Sat, 15 Apr 2023 09:28:00 +0900

Installing ZooKeeper

Download ZooKeeper from the site below and extract it to an appropriate location.

https://zookeeper.apache.org/releases.html

% mkdir zookeeper
% mv apache-zookeeper-3.8.1-bin.tar.gz zookeeper
% cd zookeeper
% tar -zxvf apache-zookeeper-3.8.1-bin.tar.gz

After extraction, the apache-zookeeper-3.8.1-bin directory is created.

ZooKeeper Configuration File

To start ZooKeeper, a configuration file is required, so create the conf/zoo.cfg file.

First, check the files in conf.

% cd apache-zookeeper-3.8.1-bin/conf
% ls
configuration.xsl logback.xml       zoo_sample.cfg

Create conf/zoo.cfg with the following content.

tickTime=2000
initLimit=10
syncLimit=5
dataDir=/tmp/zookeeper
clientPort=2181

tickTime: heartbeat time in milliseconds.
dataDir: path for storing in-memory database snapshots and logs written when the database is updated.
clientPort: port that listens for client connections.

Running ZooKeeper

You can now run ZooKeeper.

% bin/zkServer.sh start

ZooKeeper Replication

If you install and run it this way, ZooKeeper runs in standalone mode and has no replication. Therefore, if the ZooKeeper process dies, the service will stop.
To apply replication, see Running Replicated ZooKeeper.

Installing ZooKeeper with Docker for a Development Environment

kc@example.com (kc kim) — Sat, 15 Apr 2023 07:43:00 +0900

Docker Images

We will install ZooKeeper in a Docker environment using the Docker images below.

Official ZooKeeper Docker image
- https://hub.docker.com/_/zookeeper/
ZooKeeper Web Docker image
- https://hub.docker.com/r/noteax/zk-web-docker

Docker Configuration and Execution

Create a Working Directory

Create a working directory in an appropriate location.

% mkdir zookeeper
% cd zookeeper

Write docker-compose

Create docker-compose.yml and write the following content.

version: '3.1'
services:
  zookeeper:
    container_name: zookeeper-server
    image: zookeeper
    ports:
      - 2181:2181

Run docker-compose

After writing the yml file, run it with the following command.

docker-compose -f docker-compose.yml up -d

Check the Docker Container

When you run the command above, you can confirm that Kafka and Zookeeper are running.

docker ps -a

% docker ps -a
CONTAINER ID   IMAGE                      COMMAND                  CREATED          STATUS                   PORTS                                                  NAMES
6f95cc0e6a9a   zookeeper                  "/docker-entrypoint.…"   17 seconds ago   Up 16 seconds            2888/tcp, 3888/tcp, 0.0.0.0:2181->2181/tcp, 8080/tcp   zookeeper

Install web-console

Install a web-console for easier use.

Add the ZK-Web console Docker service to the yml file written above.

version: '3.7'
services:
  zookeeper:
    container_name: zookeeper-server
    image: zookeeper
    ports:
      - 2181:2181
  zk-web:
    container_name: zk-web-server
    image: goodguide/zk-web
    ports:
      - 8080:8080
    environment:
      - ZKWEB_PORT=8080                 # Web Port
      - ZKWEB_CREDENTIALS=admin:hello   # Admin account:password
      - ZKWEB_DEFAULT_NODE=localhost:2181/default-node

networks:
  promnet:
    driver: bridge

Remove the existing docker-compose environment with the rm command, and then run it again with up.

% docker-compose stop
% docker-compose rm
% docker-compose -f docker-compose.yml up -d

If it is installed correctly, you can access zk-web at localhost:8080.

Check znode in web-console

First, check the ZooKeeper server address.

Check the container ID with the ps command.

% docker ps -a
CONTAINER ID   IMAGE                  COMMAND                  CREATED         STATUS        PORTS                                                  NAMES
fdf840485d3d   zookeeper              "/docker-entrypoint.…"   2 seconds ago   Up 1 second   2888/tcp, 3888/tcp, 0.0.0.0:2181->2181/tcp, 8080/tcp   zookeeper
5e55c24e6186   noteax/zk-web-docker   "/docker-entrypoint.…"   2 seconds ago   Up 1 second   0.0.0.0:8080->8080/tcp                                 zk_web

Enter the confirmed ID as shown below and run the inspect command.

docker inspect ${CONTAINER ID}

With the inspect command, check the container’s Gateway IP under NetworkSettings > Networks > Gateway.

% docker inspect fdf840485d3d
[
        ...
        "NetworkSettings": {
            ...
            "Networks": {
                "zookeeper_default": {
                    ...
                    "Gateway": "172.20.0.1",
                    ...
                }
            }
        }
        ...
]

In the example above, the Gateway IP is 172.20.0.1.

Go to ZK-Web and enter {Gateway IP}:2181 in the input field below. Based on the example above, enter 172.20.0.1:2181.

Click the login button and log in with the admin account configured above. You can then create, edit, and delete data.

Cluster Configuration

You can easily configure a cluster with the following settings.

version: '3.7'
services:
  zk1:
    image: zookeeper
    hostname: zk1
    ports:
      - 2181:2181
    environment:
      ZOO_MY_ID: 1
      ZOO_SERVERS: server.1=0.0.0.0:2888:3888;2181 server.2=zk2:2888:3888;2181 server.3=zk3:2888:3888;2181
    restart: always
  zk2:
    image: zookeeper
    hostname: zk2
    ports:
      - 2182:2181
    environment:
      ZOO_MY_ID: 2
      ZOO_SERVERS: server.1=zk1:2888:3888;2181 server.2=0.0.0.0:2888:3888;2181 server.3=zk3:2888:3888;2181
    restart: always
  zk3:
    image: zookeeper
    hostname: zk3
    ports:
      - 2183:2181
    environment:
      ZOO_MY_ID: 3
      ZOO_SERVERS: server.1=zk1:2888:3888;2181 server.2=zk2:2888:3888;2181 server.3=0.0.0.0:2888:3888;2181
    restart: always

  zk-web:
    container_name: zk_web
    image: noteax/zk-web-docker
    ports:
      - 8080:8080
    environment:
      - ZKWEB_PORT=8080                # Web Port
      - ZKWEB_CREDENTIALS=admin:hello  # Admin account:password
      - ZKWEB_DEFAULT_NODE=localhost:2181/default-node
    restart: always

devkuma – ZooKeeper