Open a port of a docker zookeeper container - linux

Question

I'm installing zookeeper on my container.
What I've done is:
root#46966b33c3a1:/opt:> wget https://downloads.apache.org/zookeeper/zookeeper-3.6.2/apache-zookeeper-3.6.2-bin.tar.gz
root#46966b33c3a1:/opt:> tar zxf apache-zookeeper-3.6.2-bin.tar.gz
root#46966b33c3a1:/opt:> cd apache-zookeeper-3.6.2-bin
root#46966b33c3a1:/opt/apache-zookeeper-3.6.2-bin:> cp conf/zoo_sample.cfg conf/zoo.cfg
root#46966b33c3a1:/opt/apache-zookeeper-3.6.2-bin:> vi conf/zoo.cfg
root#46966b33c3a1:/opt/apache-zookeeper-3.6.2-bin:> ./bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /opt/apache-zookeeper-3.6.2-bin/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
zoo.cfg
tickTime=2000
dataDir=/opt/apache-zookeeper-3.6.2-bin/data
clientPort=2181
initLimit=5
syncLimit=2
It looked like zk sever started without a problem.
However, when I try to connect to zk CLI, an error occurs:
2021-02-09 22:59:16,920 [myid:localhost:2181] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread#1167] - Opening socket connection to server localhost/127.0.0.1:2181.
2021-02-09 22:59:16,921 [myid:localhost:2181] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread#1169] - SASL config status: Will not attempt to authenticate using SASL (unknown error)
JLine support is enabled
2021-02-09 22:59:17,001 [myid:localhost:2181] - WARN [main-SendThread(localhost:2181):ClientCnxn$SendThread#1285] - Session 0x0 for sever localhost/127.0.0.1:2181, Closing socket connection. Attempting reconnect except it is a SessionExpiredException.
java.net.ConnectException: Connection refused
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:344)
at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1275)
So, I checked a connection to 2181 port.
root#46966b33c3a1:/opt/apache-zookeeper-3.6.2-bin:> telnet localhost 2181
Trying 127.0.0.1...
telnet: connect to address 127.0.0.1: Connection refused
Trying ::1...
telnet: connect to address ::1: Network is unreachable
root#46966b33c3a1:/opt/apache-zookeeper-3.6.2-bin:> hostname -i
172.17.0.2
root#46966b33c3a1:/opt/apache-zookeeper-3.6.2-bin:> telnet 172.17.0.2 2181
Trying 172.17.0.2...
telnet: connect to address 172.17.0.2: Connection refused
Connection is refused.
How can I resolve this?

Answer 1

You can use the zookeeper official docker image. You can use docker-compose instead of doing manual zookeeper installation inside a docker.
Here is a sample docker-compose file. You can modify other configs from documentation based on your requirement.
version: '3.9'
services:
zoo1:
image: zookeeper
restart: always
hostname: zoo1
ports:
- 2181:2181
environment:
ZOO_MY_ID: 1
ZOO_SERVERS: server.1=0.0.0.0:2888:3888;2181 server.2=zoo2:2888:3888;2181 server.3=zoo3:2888:3888;2181
ZOO_TICK_TIME: 2000
ZOO_INIT_LIMIT: 5
ZOO_SYNC_LIMIT: 2
zoo2:
image: zookeeper
restart: always
hostname: zoo2
ports:
- 2182:2181
environment:
ZOO_MY_ID: 2
ZOO_SERVERS: server.1=zoo1:2888:3888;2181 server.2=0.0.0.0:2888:3888;2181 server.3=zoo3:2888:3888;2181
ZOO_TICK_TIME: 2000
ZOO_INIT_LIMIT: 5
ZOO_SYNC_LIMIT: 2
zoo3:
image: zookeeper
restart: always
hostname: zoo3
ports:
- 2183:2181
environment:
ZOO_MY_ID: 3
ZOO_SERVERS: server.1=zoo1:2888:3888;2181 server.2=zoo2:2888:3888;2181 server.3=0.0.0.0:2888:3888;2181
ZOO_TICK_TIME: 2000
ZOO_INIT_LIMIT: 5
ZOO_SYNC_LIMIT: 2