1. Set up zookeeper cluster
1.1 problems
This case requires:
- Set up zookeeper cluster
- 1 leader
- 2 follower s
- 1 observer
1.2 steps
To implement this case, you need to follow the following steps.
Step 1: install Zookeeper
1) Edit / etc/hosts and all cluster hosts can ping each other (configured on Hadoop 1 and synchronized to node-0001, node-0002 and node-0003)
[root@hadoop1 hadoop]# vim /etc/hosts
192.168.1.50 hadoop1
192.168.1.51 node-0001
192.168.1.52 node-0002
192.168.1.53 node-0003
192.168.1.56 newnode
[root@nn01 hadoop]# for i in {52..54} \
do \
scp /etc/hosts 192.168.1.$i:/etc/ \
done //Synchronous configuration
hosts 100% 253 639.2KB/s 00:00
hosts 100% 253 497.7KB/s 00:00
hosts 100% 253 662.2KB/s 00:00
2) Install java-1.8.0-openjdk-devel. Since hadoop has been installed before, it will not be installed here. If it is a new machine, it will be installed
3) Extract and copy zookeeper to / usr/local/zookeeper
[root@hadoop1 ~]# tar -xf zookeeper-3.4.13.tar.gz [root@hadoop1 ~]# mv zookeeper-3.4.13 /usr/local/zookeeper
4) Change the name of the configuration file and add the configuration at the end
[root@hadoop1 ~]# cd /usr/local/zookeeper/conf/ [root@hadoop1 conf]# ls configuration.xsl log4j.properties zoo_sample.cfg [root@hadoop1 conf]# mv zoo_sample.cfg zoo.cfg [root@hadoop1 conf]# chown root.root zoo.cfg [root@hadoop1 conf]# vim zoo.cfg server.1=node-0001:2888:3888 server.2=node-0002:2888:3888 server.3=node-0003:2888:3888 server.4=hadoop1:2888:3888:observer
5) Copy / usr/local/zookeeper to another cluster host
[root@hadoop1 conf]# for i in {52..54}; do rsync -aSH --delete /usr/local/zookeeper/ 192.168.1.$i:/usr/local/zookeeper -e 'ssh' & done
[4] 4956
[5] 4957
[6] 4958
6) Create mkdir /tmp/zookeeper, each
[root@hadoop1 conf]# mkdir /tmp/zookeeper [root@hadoop1 conf]# ssh node-0001 mkdir /tmp/zookeeper [root@hadoop1 conf]# ssh node-0002 mkdir /tmp/zookeeper [root@hadoop1 conf]# ssh node-0003 mkdir /tmp/zookeeper
7) Create a myid file. The id must be the server corresponding to the hostname in the configuration file (id) consistent
[root@hadoop1 conf]# echo 4 >/tmp/zookeeper/myid [root@hadoop1 conf]# ssh node-0001 'echo 1 >/tmp/zookeeper/myid' [root@hadoop1 conf]# ssh node-0002 'echo 2 >/tmp/zookeeper/myid' [root@hadoop1 conf]# ssh node-0003 'echo 3 >/tmp/zookeeper/myid'
8) Start the service. You can't view the status of a single machine. You need to start all clusters before you can view the status. Each machine should be started manually (take Hadoop 1 as an example)
[root@hadoop1 conf]# /usr/local/zookeeper/bin/zkServer.sh start ZooKeeper JMX enabled by default Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg Starting zookeeper ... STARTED
Note: when you start zookeeper to check the status, an error is reported. The number of starts should be more than half. Then you can see it again
9) View status
[root@hadoop1 conf]# /usr/local/zookeeper/bin/zkServer.sh status ZooKeeper JMX enabled by default Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg Mode: observe [root@hadoop1 conf]# /usr/local/zookeeper/bin/zkServer.sh stop //View status after shutdown roles of other servers ZooKeeper JMX enabled by default Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg Stopping zookeeper ... STOPPED
2. Test the remote management and high availability of the cluster
2.1 problems
This case requires:
- Test the remote management and high availability of the cluster
2.2 steps
To implement this case, you need to follow the following steps.
Step 1: test the remote management and high availability of the cluster
[root@hadoop1 conf]# socat - TCP:node1:2181
stat
... ...
Outstanding: 0
Zxid: 0x0
Mode: follower
Node count: 4
[root@hadoop1 conf]# vim api.sh
#!/bin/bash
function getstatus(){
exec 9<>/dev/tcp/$1/2181 2>/dev/null
echo stat >&9
MODE=$(cat <&9 |grep -Po "(?<=Mode:).*")
exec 9<&-
echo ${MODE:-NULL}
}
for i in node{1..3} hadoop1;do
echo -ne "${i}\t"
getstatus ${i}
done
[root@hadoop1 conf]# chmod 755 api.sh
[root@hadoop1 conf]# ./api.sh
node-0001 follower
node-0002 leader
node-0003 follower
hadoop1 observer
3. Build three kafka on the node
3.1 problems
This case requires:
- Build 3 kafka on node
- node-0001
- node-0002
- node-0003
- Publish subscribe message test
3.2 steps
To implement this case, you need to follow the following steps.
Step 1: build Kafka cluster
1) Unzip the kafka package
Kafka can operate on node-0001, node-0002 and node-0003
[root@node-0001 hadoop]# tar -xf kafka_2.12-2.1.0.tgz
2) Copy kafka to / usr/local/kafka
[root@node-0001 ~]# mv kafka_2.12-2.1.0 /usr/local/kafka
3) Modify the configuration file / usr / local / Kafka / config / server properties
[root@node-0001 ~]# cd /usr/local/kafka/config [root@node-0001 config]# vim server.properties broker.id=22 zookeeper.connect=node-0001:2181,node-0002:2181,node-0003:2181
4) Copy kafka to another host and modify the broker ID, cannot be repeated
[root@node-0001 config]# for i in 53 54; do rsync -aSH --delete /usr/local/kafka 192.168.1.$i:/usr/local/; done [1] 27072 [2] 27073 [root@node-0002 ~]# vim /usr/local/kafka/config/server.properties //node-0002 host modification broker.id=23 [root@node-0003 ~]# vim /usr/local/kafka/config/server.properties //node-0003 host modification broker.id=24
5) Start kafka cluster (node-0001, node-0002, node-0003 start)
[root@node-0001 local]# /usr/local/kafka/bin/kafka-server-start.sh -daemon /usr/local/kafka/config/server.properties [root@node-0001 local]# jps / / kafka appears 26483 DataNode 27859 Jps 27833 Kafka 26895 QuorumPeerMain
6) Verify the configuration and create a topic
[root@node-0001 local]# /usr/local/kafka/bin/kafka-topics.sh --create --partitions 1 --replication-factor 1 --zookeeper localhost:2181 --topic mymsg
Created topic "mymsg".
\7) Simulate producers and release messages
[root@node-0002 ~]# /usr/local/kafka/bin/kafka-console-producer.sh --broker-list localhost:9092 --topic mymsg
//Write a data
ccc
ddd
9) Simulate consumers and receive messages
[root@node-0003 ~]# /usr/local/kafka/bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic mymsg
//This side will synchronize directly
ccc
ddd
Note: kafka eats more memory. You can stop it after this kafka experiment
4. Prepare the experimental environment
4.1 problems
This case requires:
- All nodes
- 192.168.1.50 hadoop1
- 192.168.1.56 hadoop2
- 192.168.1.51 node-0001
- 192.168.1.52 node-0002
- 192.168.1.53 node-0003
- Install java-1.8.0-openjdk-devel on the new machine
- New machine configuration / etc/hosts
- Configure ssh key free login for the new machine
- Modify profile
4.2 scheme
Configure the high availability of Hadoop to solve the single point of failure of NameNode. Use the Hadoop cluster built before, and add a Hadoop 2 with an ip of 192.168.1.56. The specific requirements are shown in figure-1:
Figure-1
4.3 steps
To implement this case, you need to follow the following steps.
Step 1: high availability of hadoop
1) Stop all services (since kafka's experiment has been stopped after it is completed, it will not be repeated here)
[root@hadoop1 ~]# cd /usr/local/hadoop/ [root@hadoop1 hadoop]# ./sbin/stop-all.sh / / stop all services
2) Start zookeeper (you need to start one by one). Here, take Hadoop 1 as an example
[root@hadoop1 hadoop]# /usr/local/zookeeper/bin/zkServer.sh start [root@hadoop1 hadoop]# sh /usr/local/zookeeper/conf/api.sh / / use the previously written script to view node-0001 follower node-0002 leader node-0003 follower hadoop1 observer
3) Add a new machine Hadoop 2. There was a new node here, which can be used as Hadoop 2
[root@newnode ~]# echo hadoop2 > /etc/hostname [root@newnode ~]# hostname hadoop2
4) Modify vim /etc/hosts
[root@hadoop1 hadoop]# vim /etc/hosts 192.168.1.50 hadoop1 192.168.1.56 hadoop2 192.168.1.51 node-0001 192.168.1.52 node-0002 192.168.1.53 node-0003
5) Synchronize to Hadoop 2, node-0001, node-0002, node-0003
[root@hadoop1 hadoop]# for i in {51..53} 56; do rsync -aSH --delete /etc/hosts 192.168.1.$i:/etc/hosts -e 'ssh' & done
[1] 14355
[2] 14356
[3] 14357
[4] 14358
6) Configure SSH trust
Note: Hadoop 1 and Hadoop 2 do not need a password to connect with each other. Hadoop 2 does not need a password to connect itself with node-0001, node-0002 and node-0003
[root@hadoop2 ~]# vim /etc/ssh/ssh_config
Host *
GSSAPIAuthentication yes
StrictHostKeyChecking no
[root@hadoop1 hadoop]# cd /root/.ssh/
[root@hadoop1 .ssh]# scp id_rsa id_rsa.pub hadoop2:/root/.ssh/
//Give Hadoop 2 the public key and private key of Hadoop 1
7) Delete / var/hadoop from all hosts/*
[root@hadoop1 .ssh]# rm -rf /var/hadoop/*
5. Configure namenode and resource manager for high availability
5.1 problems
This case requires:
- Configure namenode and resource manager high availability
- hadoop-env.sh
- core-site.xml
- hdfs-site.xml
- mapred-site.xml
- yarn-site.xml
- slaves
5.2 steps
To implement this case, you need to follow the following steps.
Step 1: high availability of hadoop
1) Configure core site
[root@hadoop1 .ssh]# vim /usr/local/hadoop/etc/hadoop/core-site.xml
<configuration>
<property>
<name>fs.defaultFS</name>
<value>hdfs://nsdcluster</value>
//nsdcluster is a casual name. It is equivalent to a group. You can access this group when accessing
</property>
<property>
<name>hadoop.tmp.dir</name>
<value>/var/hadoop</value>
</property>
<property>
<name>ha.zookeeper.quorum</name>
<value>node-0001:2181,node-0002:2181,node-0003:2181</value> //zookeepe's address
</property>
<property>
<name>hadoop.proxyuser.nfs.groups</name>
<value>*</value>
</property>
<property>
<name>hadoop.proxyuser.nfs.hosts</name>
<value>*</value>
</property>
</configuration>
2) Configure HDFS site
[root@hadoop1 ~]# vim /usr/local/hadoop/etc/hadoop/hdfs-site.xml
<configuration>
<property>
<name>dfs.replication</name>
<value>2</value>
</property>
<property>
<name>dfs.nameservices</name>
<value>nsdcluster</value>
</property>
<property>
<name>dfs.ha.namenodes.nsdcluster</name>
//nn1 and nn2 have fixed names and are built-in variables. There are nn1 and nn2 in nsdcluster
<value>nn1,nn2</value>
</property>
<property>
<name>dfs.namenode.rpc-address.nsdcluster.nn1</name>
//Declare nn1 8020 as the communication port, which is the rpc communication port of Hadoop 1
<value>hadoop1:8020</value>
</property>
<property>
<name>dfs.namenode.rpc-address.nsdcluster.nn2</name>
//Declare who nn2 is and the rpc communication port of Hadoop 2
<value>hadoop2:8020</value>
</property>
<property>
<name>dfs.namenode.http-address.nsdcluster.nn1</name>
//http communication port of Hadoop 1
<value>hadoop1:50070</value>
</property>
<property>
<name>dfs.namenode.http-address.nsdcluster.nn2</name>
//http communication ports of Hadoop 1 and Hadoop 2
<value>hadoop2:50070</value>
</property>
<property>
<name>dfs.namenode.shared.edits.dir</name>
//Specify the path where the namenode metadata is stored in the journalnode
<value>qjournal://node-0001:8485;node-0002:8485;node-0003:8485/nsdcluster</value>
</property>
<property>
<name>dfs.journalnode.edits.dir</name>
//Specifies the path to the journalnode log file store
<value>/var/hadoop/journal</value>
</property>
<property>
<name>dfs.client.failover.proxy.provider.nsdcluster</name>
//Specifies the java class of HDFS client connection active namenode
<value>org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider</value>
</property>
<property>
<name>dfs.ha.fencing.methods</name> //Configure the isolation mechanism as ssh
<value>sshfence</value>
</property>
<property>
<name>dfs.ha.fencing.ssh.private-key-files</name> //Specify the location of the key
<value>/root/.ssh/id_rsa</value>
</property>
<property>
<name>dfs.ha.automatic-failover.enabled</name> //Turn on automatic failover
<value>true</value>
</property>
</configuration>
3) Configure yarn site
[root@hadoop1 ~]# vim /usr/local/hadoop/etc/hadoop/yarn-site.xml
<configuration>
<!-- Site specific YARN configuration properties -->
<property>
<name>yarn.nodemanager.aux-services</name>
<value>mapreduce_shuffle</value>
</property>
<property>
<name>yarn.resourcemanager.ha.enabled</name>
<value>true</value>
</property>
<property>
<name>yarn.resourcemanager.ha.rm-ids</name> //RM1 and RM2 represent Hadoop 1 and Hadoop 2
<value>rm1,rm2</value>
</property>
<property>
<name>yarn.resourcemanager.recovery.enabled</name>
<value>true</value>
</property>
<property>
<name>yarn.resourcemanager.store.class</name>
<value>org.apache.hadoop.yarn.server.resourcemanager.recovery.ZKRMStateStore</value>
</property>
<property>
<name>yarn.resourcemanager.zk-address</name>
<value>node-0001:2181,node-0002:2181,node-0003:2181</value>
</property>
<property>
<name>yarn.resourcemanager.cluster-id</name>
<value>yarn-ha</value>
</property>
<property>
<name>yarn.resourcemanager.hostname.rm1</name>
<value>hadoop1</value>
</property>
<property>
<name>yarn.resourcemanager.hostname.rm2</name>
<value>hadoop2</value>
</property>
</configuration>
6. Start the service and verify high availability
6.1 problems
This case requires:
- Start the service and verify high availability
- Stop an active node while analyzing data
- Verify high availability status and data
6.2 steps
To implement this case, you need to follow the following steps.
Step 1: hadoop high availability verification
1) Synchronize to Hadoop 2, node-0001, node-0002, node-0003
[root@hadoop1 ~]# for i in {51..53} 56; do rsync -aSH --delete /usr/local/hadoop/ 192.168.1.$i:/usr/local/hadoop -e 'ssh' & done
[1] 25411
[2] 25412
[3] 25413
[4] 25414
2) Delete / user/local/hadoop/logs on all machines to facilitate troubleshooting
[root@hadoop1 ~]# for i in {50..53} 56; do ssh 192.168.1.$i rm -rf /usr/local/hadoop/logs ; done
3) Synchronous configuration
[root@hadoop1 ~]# for i in {51..53} 56; do rsync -aSH --delete /usr/local/hadoop 192.168.1.$i:/usr/local/hadoop -e 'ssh' & done
[1] 28235
[2] 28236
[3] 28237
[4] 28238
4) Initialize ZK cluster
[root@hadoop1 ~]# /usr/local/hadoop/bin/hdfs zkfc -formatZK ... 18/09/11 15:43:35 INFO ha.ActiveStandbyElector: Successfully created /hadoop-ha/nsdcluster in ZK //Successful is success ...
5) Start the journalnode service on node-0001, node-0002 and node-0003 (take node-0001 as an example)
[root@node-0001 ~]# /usr/local/hadoop/sbin/hadoop-daemon.sh start journalnode starting journalnode, logging to /usr/local/hadoop/logs/hadoop-root-journalnode-node-0001.out [root@node-0001 ~]# jps 29262 JournalNode 26895 QuorumPeerMain 29311 Jps
6) For formatting, start journalnode on node-0001, node-0002 and node-0003 before formatting
[root@hadoop1 ~]# /usr/local/hadoop//bin/hdfs namenode -format //Successful is success [root@hadoop1 hadoop]# ls /var/hadoop/ dfs
7) Hadoop 2 data synchronization to local / var/hadoop/dfs
[root@hadoop2 ~]# cd /var/hadoop/ [root@hadoop2 hadoop]# ls [root@hadoop2 hadoop]# rsync -aSH hadoop1:/var/hadoop/ /var/hadoop/ [root@hadoop2 hadoop]# ls dfs
8) Initialize JNS
[root@hadoop1 hadoop]# /usr/local/hadoop/bin/hdfs namenode -initializeSharedEdits 18/09/11 16:26:15 INFO client.QuorumJournalManager: Successfully started new epoch 1 //Successfully appears, and a node is successfully opened
9) Stop the journalnode service (node-0001, node-0002, node-0003)
[root@node-0001 hadoop]# /usr/local/hadoop/sbin/hadoop-daemon.sh stop journalnode stopping journalnode [root@node-0001 hadoop]# jps 29346 Jps 26895 QuorumPeerMain
Step 2: start the cluster
1) Hadoop 1 operation above
[root@hadoop1 hadoop]# /usr/local/hadoop/sbin/start-all.sh / / start all clusters This script is Deprecated. Instead use start-dfs.sh and start-yarn.sh Starting namenodes on [hadoop1 hadoop2] hadoop1: starting namenode, logging to /usr/local/hadoop/logs/hadoop-root-namenode-hadoop1.out hadoop2: starting namenode, logging to /usr/local/hadoop/logs/hadoop-root-namenode-hadoop2.out node-0002: starting datanode, logging to /usr/local/hadoop/logs/hadoop-root-datanode-node-0002.out node-0003: starting datanode, logging to /usr/local/hadoop/logs/hadoop-root-datanode-node-0003.out node-0001: starting datanode, logging to /usr/local/hadoop/logs/hadoop-root-datanode-node-0001.out Starting journal nodes [node-0001 node-0002 node-0003] node-0001: starting journalnode, logging to /usr/local/hadoop/logs/hadoop-root-journalnode-node-0001.out node-0003: starting journalnode, logging to /usr/local/hadoop/logs/hadoop-root-journalnode-node-0003.out node-0002: starting journalnode, logging to /usr/local/hadoop/logs/hadoop-root-journalnode-node-0002.out Starting ZK Failover Controllers on NN hosts [hadoop1 hadoop2] hadoop1: starting zkfc, logging to /usr/local/hadoop/logs/hadoop-root-zkfc-hadoop1.out hadoop2: starting zkfc, logging to /usr/local/hadoop/logs/hadoop-root-zkfc-hadoop2.out starting yarn daemons starting resourcemanager, logging to /usr/local/hadoop/logs/yarn-root-resourcemanager-hadoop1.out node-0002: starting nodemanager, logging to /usr/local/hadoop/logs/yarn-root-nodemanager-node-0002.out node-0001: starting nodemanager, logging to /usr/local/hadoop/logs/yarn-root-nodemanager-node-0001.out node-0003: starting nodemanager, logging to /usr/local/hadoop/logs/yarn-root-nodemanager-node-0003.out
2) Hadoop 2 operation above
[root@hadoop2 hadoop]# /usr/local/hadoop/sbin/yarn-daemon.sh start resourcemanager starting resourcemanager, logging to /usr/local/hadoop/logs/yarn-root-resourcemanager-hadoop2.out
3) View cluster status
[root@hadoop1 hadoop]# /usr/local/hadoop/bin/hdfs haadmin -getServiceState nn1 active [root@hadoop1 hadoop]# /usr/local/hadoop/bin/hdfs haadmin -getServiceState nn2 standby [root@hadoop1 hadoop]# /usr/local/hadoop/bin/yarn rmadmin -getServiceState rm1 active [root@hadoop1 hadoop]# /usr/local/hadoop/bin/yarn rmadmin -getServiceState rm2 standby
4) Check whether the node is joined
[root@hadoop1 hadoop]# /usr/local/hadoop/bin/hdfs dfsadmin -report
...
Live datanodes (3): //There will be three nodes
...
[root@hadoop1 hadoop]# /usr/local/hadoop/bin/yarn node -list
Total Nodes:3
Node-Id Node-State Node-Http-Address Number-of-Running-Containers
node-0002:43307 RUNNING node-0002:8042 0
node-0001:34606 RUNNING node-0001:8042 0
node-0003:36749 RUNNING node-0003:8042
Step 3: access the cluster
1) View and create
[root@hadoop1 hadoop]# /usr/local/hadoop/bin/hadoop fs -ls / [root@hadoop1 hadoop]# /Usr / local / Hadoop / bin / Hadoop FS - MKDIR / aa / / create aa [root@hadoop1 hadoop]# /Usr / local / Hadoop / bin / Hadoop FS - LS / / view again Found 1 items drwxr-xr-x - root supergroup 0 2018-09-11 16:54 /aa [root@hadoop1 hadoop]# /usr/local/hadoop/bin/hadoop fs -put *.txt /aa [root@hadoop1 hadoop]# /usr/local/hadoop/bin/hadoop fs -ls hdfs://nsdcluster/aa //You can also view it this way Found 3 items -rw-r--r-- 2 root supergroup 86424 2018-09-11 17:00 hdfs://nsdcluster/aa/LICENSE.txt -rw-r--r-- 2 root supergroup 14978 2018-09-11 17:00 hdfs://nsdcluster/aa/NOTICE.txt -rw-r--r-- 2 root supergroup 1366 2018-09-11 17:00 hdfs://nsdcluster/aa/README.txt
2) Verify high availability and close active namenode
[root@hadoop1 hadoop]# /usr/local/hadoop/bin/hdfs haadmin -getServiceState nn1 active [root@hadoop1 hadoop]# /usr/local/hadoop/sbin/hadoop-daemon.sh stop namenode stopping namenode [root@hadoop1 hadoop]# /usr/local/hadoop/bin/hdfs haadmin -getServiceState nn1 //If you check it again, an error will be reported [root@hadoop1 hadoop]# /usr/local/hadoop/bin/hdfs haadmin -getServiceState nn2 //Hadoop 2 has changed from standby to active active [root@hadoop1 hadoop]# /usr/local/hadoop/bin/yarn rmadmin -getServiceState rm1 active [root@hadoop1 hadoop]# /usr/local/hadoop/sbin/yarn-daemon.sh stop resourcemanager //Stop resourcemanager [root@hadoop1 hadoop]# /usr/local/hadoop/bin/yarn rmadmin -getServiceState rm2 active
3) Recovery node
[root@hadoop1 hadoop]# /usr/local/hadoop/sbin/hadoop-daemon.sh start namenode //Start namenode [root@hadoop1 hadoop]# /usr/local/hadoop/sbin/yarn-daemon.sh start resourcemanager //Start resourcemanager [root@hadoop1 hadoop]# /usr/local/hadoop/bin/hdfs haadmin -getServiceState nn1 //see [root@hadoop1 hadoop]# /usr/local/hadoop/bin/yarn rmadmin -getServiceState rm1 //see
Exercise
1 briefly describe what Zookeeper is and its role
What is Zookeeper:
Zookeeper is an open source distributed application coordination service
effect:
It is used to ensure the transaction consistency of data between clusters
2. Briefly describe the role and characteristics of Zookeeper
Leader: accept the proposal requests of all followers, coordinate the voting of the proposal uniformly, and be responsible for internal data exchange with all followers
Follower: directly serve the client, participate in the voting of the proposal, and exchange data with the Leader
Observer: directly serves the client, but does not participate in the voting of the proposal, and also exchanges data with the Leader
3 how to view the status of Zookeeper using api
[root@nn01 conf]# /usr/local/zookeeper/bin/zkServer.sh start
[root@nn01 conf]# vim api.sh
#!/bin/bash
function getstatus(){
exec 9<>/dev/tcp/$1/2181 2>/dev/null
echo stat >&9
MODE=$(cat <&9 |grep -Po "(?<=Mode:).*")
exec 9<&-
echo ${MODE:-NULL}
}
for i in node{1..3} nn01;do
echo -ne "${i}\t"
getstatus ${i}
done
[root@nn01 conf]# chmod 755 api.sh
[root@nn01 conf]# ./api.sh
node1 follower
node2 leader
node3 follower
nn01 observer
4 how to create a topic in Kafka cluster
[root@node1 local]# /usr/local/kafka/bin/kafka-topics.sh --create --partitions 1 --replication-factor 1 --zookeeper node3:2181 --topic aa Created topic "aa".
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