I've a local Apache Kafka setup and there are total 2 broker (id - 0 and 1) on port 9092 and 9093.
I created a topic and published the messages using this command:
bin/kafka-console.-producer.sh --broker-list localhost:9092 --topic test
Then I consumed the messages on other terminal using the command:
bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic test
Till now everything is fine.
But when i type command -
bin/kafka-console.-producer.sh --broker-list localhost:9093 --topic test
and write some messages it is showing in the 2nd terminal where I've typed this command -
bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic test
Why port 9093 messages are publishing to 9092?
Your cluster contains of two brokers. It is not important which host you use for initial connection. Using kafka client you don't specify from which broker you consume or to which your produce messages. Those hostname are only to discover whole list of kafka brokers (cluster)
According to documentation:
https://kafka.apache.org/documentation/#producerconfigs
https://kafka.apache.org/documentation/#consumerconfigs
bootstrap.servers::
A list of host/port pairs to use for establishing the initial connection to the Kafka cluster. The client will make use of all servers irrespective of which servers are specified here for bootstrapping—this list only impacts the initial hosts used to discover the full set of servers.
Related
I am very new to Kafka. Following a few tutorials, I have the following questions regarding consuming actual Kafka topics.
The situation: there is a server in my workplace that is streaming Kafka topics. I have the topic name. I would like to consume this topic from my machine (Windows WSL2 Ubuntu). From this tutorial, I am able to
Run zookeeper with this command:
bin/zookeeper-server-start.sh config/zookeeper.properties
Create a broker with:
bin/kafka-server-start.sh config/server.properties
Run a producer console, with a fake topic named quickstart-events at port localhost:9092:
bin/kafka-console-producer.sh --topic quickstart-events --bootstrap-server localhost:9092
Run a consumer console listening to localhost:9092 and receive the streaming data from the producer:
bin/kafka-console-consumer.sh --topic quickstart-events --from-beginning --bootstrap-server localhost:9092
Now for my real situation: if I know the topic name, what else do I need in order to apply the same steps above to listen to it as a consumer? What are the steps involved? I read in other threads about tunnelling with Jumphost. How to do that?
I understand this question is rather generic. Appreciate any pointers to any relevant readings or guidance.
Based on your company nameserver the next procedure should be done in your wsl instance
To gain outside connection
unable to access network from WSL2
You need to set bootstrap-server to your company server
--bootstrap-server my.company.com:9092
I have created two kafka brokers in a kafka cluster. When one broker is down I am not able to get any data to kafka consumer.
I am using this command to read messages from consumer:
bin/kafka-console-consumer.sh --topic test_kafka_cluster \
--bootstrap-server 127.0.0.1:9092,127.0.0.2:9092 --from-beginning
Here as per your console consumer configuration, IP address used here are 127.0.0.1 and 127.0.0.2 and two bootstrap servers are configured as 9092.
Verify both the ip's are reachable
bin/kafka-console-consumer.sh --topic test_kafka_cluster \
--bootstrap-server 127.0.0.1:9092,127.0.0.2:9092 --from-beginning
Ideally when we run tow kafka broker instance it will be running in two different ports.
Presuming Kafka is running in local
Eg: localhost:9092 localhost:9093
Kafka instances running on two different host:
Eg: 127.0.0.3:9092, 127.0.0.2:9092
If Kafka is running on docker/docker toolbox:
Console consumer on Docker toolbox:
docker exec <container-name> kafka-console-consumer --bootstrap-server 192.168.99.100:9093 --topic <topic-name> --from-beginning
Console consumer on Docker:
docker exec <container-name> kafka-console-consumer --bootstrap-server localhost:9093 localhost 9092 --topic <topic-name> --from-beginning
There are two parameters that affect topics availability for a consumer:
min.insync.replicas (minISR): Minimum number of in-sync partition's replicas.
replication.factor (RF): Total number of partition's replicas.
If you want your consumer to survive a broker outage, then you must have RF > minISR. With RF=2 and minISR=2 you can't tolerate any broker down, with RF=3 and minISR=2 you can tolerate 1 broker down, with RF=5 and minISR=2 you can tolerate 3 brokers down, and so on.
Note that the internal __consumer_offsets topic is used to store consumer offsets and has a default RF value of 3, which is not achievable in your cluster of 2 nodes. So you also need to set offsets.topic.replication.factor=1 at the cluster level.
The system on which my Kafka server is running has two NICs, one with a public IP (135.220.23.45) and the other with a private one (192.168.1.14). The private NIC is connected to a subnet composed of 7 machines in total (all with addresses 192.168.1.xxx). Kafka has been installed as a service using HDP and has been configured with zookeeper.connect=192.168.1.14:2181 and listeners=PLAINTEXT://192.168.1.14:6667. I have started a consumer on the system that hosts the kafka server using: [bin/kafka-console-consumer.sh --bootstrap-server 192.168.1.14:6667 --topic test --from-beginning].
When I start producers (using [bin/kafka-console-producer.sh --broker-list 192.168.1.14:6667 --topic test]) on any of the machines on the private subnet the messages are received normally by the consumer.
I would like to start producers on public systems and receive the messages by the consumer running on the kafka server. I believed that this could be achieved by IP masquerading and by forwarding all external requests to 135.220.23.45:15501 (I have chosen 15501 to receive kafka messages) to 192.168.1.14:6667. To that extend I setup this port forwarding rule on firewalld: [port=15501:proto=tcp:toport=6670:toaddr=192.168.1.14].
However, this doesn’t seem to work since when I start a producer on an external system with [bin/kafka-console-producer.sh --broker-list 135.220.23.45:15501 --topic] the messages cannot be received by the consumer.
I have tried different kafka config settings for listeners and advertised.listeners but none of them worked. Any help will be greatly appreciated.
You need to define different endpoints for your internal and external traffic in order for this to work. As it is currently configured, when you connect to 135.220.23.45:15501 Kafka would reply with "please talk to me on 192.168.1.14:6667 which is not reachable from the outside and everything from there on out fails.
With KIP-103 Kafka was extended to cater to these scenarios by letting you define multiple endpoints.
Full disclosure, I have not yet tried this out, but something along the following lines should at least get you started down the right road.
advertised.listeners=EXTERNAL://135.220.23.45:15501,INTERNAL://192.168.1.14:6667
inter.broker.listener.name=INTERNAL
listener.security.protocol.map=EXTERNAL:PLAINTEXT,INTERNAL:PLAINTEXT
Update:
I've tested this on a cluster of three ec2 machines out of interest. I've used the following configuration:
# internal ip: 172.31.61.130
# external ip: 184.72.211.109
listeners=INTERNAL://:9092,EXTERNAL_PLAINTEXT://:9094
advertised.listeners=INTERNAL://172.31.61.130:9092,EXTERNAL_PLAINTEXT://184.72.211.109:9094
listener.security.protocol.map=INTERNAL:PLAINTEXT,EXTERNAL_PLAINTEXT:PLAINTEXT
inter.broker.listener.name=INTERNAL
And that allowed me to send messages from both an internal machine as well as my laptop at home:
# Create topic
kafka-topics --create --topic testtopic --partitions 9 --replication-factor 3 --zookeeper 127.0.0.1:2181
# Produce messages from internal machine
[ec2-user#ip-172-31-61-130 ~]$ kafka-console-producer --broker-list 127.0.0.1:9092 --topic testtopic
>internal1
>internal2
>internal3
# Produce messages from external machine
➜ bin ./kafka-console-producer --topic testtopic --broker-list 184.72.211.109:9094
external1
external2
external3
# Check topic
[ec2-user#ip-172-31-61-130 ~]$ kafka-console-consumer --bootstrap-server 172.31.52.144:9092 --topic testtopic --from-beginning
external3
internal2
external1
external2
internal3
internal1
How can I produce and consume messages from different servers?
I tried the Quickstart tutorial, but there is no instructions on how to setup for multi server clusters.
My Steps
Server A
1)bin/zookeeper-server-start.sh config/zookeeper.properties
2)bin/kafka-server-start.sh config/server.properties
3)bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor
1 --partitions 1 --topic test
4)bin/kafka-console-producer.sh --broker-list SERVER-a.IP:9092 --topic test
Server B
1A)bin/kafka-console-consumer.sh --bootstrap-server SERVER-a.IP:9092 --topic
test --from-beginning
1B)bin/kafka-console-consumer.sh --bootstrap-server SERVER-a.IP:2181 --topic
test --from-beginning
When I run 1A) consumer and enter messages into the producer, there is no messages appearing in the consumer. Its just blank.
When I run 1B consumer instead, I get a huge & very fast stream of error logs in Server A until I Ctrl+C the consumer. See below
Error log on Server A streaming at hundreds per second
WARN Exception causing close of session 0x0 due to java.io.EOFException (org.apache.zookeeper.server.NIOServerCnxn)
O Closed socket connection for client /188.166.178.40:51168 (no session established for client) (org.apache.zookeeper.server.NIOServerCnxn)
Thanks
Yes, if you want to have your producer on Server A and your consumer on server B, you are in the right direction.
You need to run a Broker on server A to make it work.
bin/kafka-server-start.sh config/server.properties
The other commands are correct.
If anyone is looking for a similar topic for kafka-steams application, it appears that multiple kafka cluster is not supported yet:
Here is a documentation from kafka: https://kafka.apache.org/10/documentation/streams/developer-guide/config-streams.html#bootstrap-servers
bootstrap.servers
(Required) The Kafka bootstrap servers. This is the same setting that is used by the underlying producer and consumer clients to connect to the Kafka cluster. Example: "kafka-broker1:9092,kafka-broker2:9092".
Tip:
Kafka Streams applications can only communicate with a single Kafka
cluster specified by this config value. Future versions of Kafka
Streams will support connecting to different Kafka clusters for
reading input streams and writing output streams.
My problem is: how can I send data from a kafka producer to broker?
the schema below explains my network configuration :
I have a producer in VM which is located in server A, and my broker too is in VM which is located in Server B.
I use an SSH connection from my producer VM to the server B with a redirection port : ssh -L 9092:192.168.56.101:9092 xx#IP1
I use kafka console to test :
bin/kafka-console-producer.sh --broker-list localhost:9092 --topic test
thanks
You need to set the --broker-list to wherever the broker resides. In your code, you are saying that I want to produce a message and send it to a broker that is on the localhost machine at port 9092. Try
bin/kafka-console-producer.sh --broker-list 192.168.56.101:9092 --topic test