Connect to the Kafka cluster

The Kafka cluster can be connected to:

• through the kcat terminal client;
• program code.

SSL and non-SSL connections are available for all methods.

Specify the port and address when connecting.

Connection ports

Use ports to connect to Kafka:

• 9092 — port for connection without SSL certificate;
• 9093 — port for connection with SSL certificate.

Addresses for connection

The address to connect to depends on the cluster subnet and where you are connecting from. You can select an address depending on one of the scenarios:

• connecting to a cluster on a public subnet;
• connect from a private subnet to a cluster on a private subnet.

You cannot connect to a cluster on a private subnet from the Internet.

Connecting to a cluster on a public subnet

If the cluster is on a public subnet, the nodes can be connected to by DNS address or IP address from the public subnet.

We recommend connecting by DNS address. For DNS addresses in the cluster, the master discovery mechanism is used — the address is bound to the node role, not to the node itself. If the master is unavailable, one of the replicas becomes the new master and the address is transferred to the new node along with the role.

When connecting using an IP address from a public subnet, the master discovery mechanism is not used. If one of the replicas becomes the new master, the master IP address will change and the connection to the old IP address will not work.

You can view the address to connect to in the control panel.

Connecting from a private subnet to a cluster on a private subnet

If you are connecting from a private subnet to a cluster on a private subnet, you can use a DNS address or a private IP address.

We recommend connecting by DNS address. For DNS addresses in the cluster, the master discovery mechanism is used — the address is bound to the node role, not to the node itself. If the master is unavailable, one of the replicas becomes the new master and the address is transferred to the new node along with the role.

When connecting by private IP address, the master discovery mechanism is not used. If one of the replicas becomes the new master, the master IP address will change and the connection using the old IP address will not work.

To connect from another private subnet, first connect both private subnets to the cloud router.

You can view the address to connect to in the control panel.

View the address for connection

1. In the Dashboard, on the top menu, click Products and select Cloud Databases.
2. Open the Active tab.
3. Open the Database Cluster page → Connection tab.
4. In the Addresses to connect block, look up the address.

Connect with SSL

Connecting using TLS(SSL)-encryption provides a secure connection between your server and the database cluster.

Bash

1. Download the root certificate and place it in the ~/.kafka/ folder:

   mkdir -p ~/.kafka/
   wget https://storage.dbaas.selcloud.ru/CA.pem -O ~/.kafka/root.crt
   chmod 0600 ~/.kafka/root.crt

2. Use the connection example for the concumer:

   kcat -C \
   -b <host>:<port> \
   -t <topic_name> \
   -X sasl.username=<user_name> \
   -X sasl.password=<password> \
   -X security.protocol=SASL_SSL \
   -X sasl.mechanisms=SCRAM-SHA-512 \
   -X ssl.ca.location=$HOME/.kafka/root.crt

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <topic_name> — topic name;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password.

3. Use the connection example for the producer:

   kcat -P \
   -b <host>:<port> \
   -t <topic_name> \
   -X sasl.username=<user_name> \
   -X sasl.password=<password> \
   -X security.protocol=SASL_SSL \
   -X sasl.mechanisms=SCRAM-SHA-512 \
   -X ssl.ca.location=$HOME/.kafka/root.crt

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <topic_name> — topic name;
   • <user_name> — the name of the user with the producer role who has access to the topic;
   • <password> — user password.

Python (confluent-kafka)

1. Download the root certificate and place it in the ~/.kafka/ folder:

   mkdir -p ~/.kafka/
   wget https://storage.dbaas.selcloud.ru/CA.pem -O ~/.kafka/root.crt
   chmod 0600 ~/.kafka/root.crt

2. Install the confluent-kafka library:

   pip install confluent-kafka

3. Use the connection example for the concumer:

   import confluent_kafka
   
   def error_callback(err):
       raise err
   
   consumer = confluent_kafka.Consumer({
       "bootstrap.servers": "<host>:<port>",
       "security.protocol": "SASL_SSL",
       "sasl.mechanism": "SCRAM-SHA-512",
       "sasl.username": "<user_name>",
       "sasl.password": "<password>",
       "group.id": "example",
       "ssl.ca.location": "<path>",
       "auto.offset.reset": "earliest",
       "enable.auto.commit": False,
       "error_cb": error_callback,
   })
   
   consumer.subscribe(["<topic_name>"])
   
   while True:
       record = consumer.poll(timeout=1.0)
       if record is not None:
           if record.error():
               if record.error().code() == confluent_kafka.KafkaError._PARTITION_EOF:
                   print(f"{record.topic()} [{record.partition()}]: reached end at offset {record.offset()}")
               elif record.error():
                   raise confluent_kafka.KafkaException(record.error())
           else:
               print(record.value())
   
   consumer.close()

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password;
   • <path> — the full path to the root certificate;
   • <topic_name> — topic name.

4. Use the connection example for the producer:

   import confluent_kafka
   
   def error_callback(err):
       raise err
   
   producer = confluent_kafka.Producer({
       "bootstrap.servers": "<host>:<port>",
       "security.protocol": "SASL_SSL",
       "sasl.mechanism": "SCRAM-SHA-512",
       "sasl.username": "<user_name>",
       "sasl.password": "<password>",
       "ssl.ca.location": "<path>",
       "error_cb": error_callback,
   })
   producer.produce("<topic_name>", "message")
   producer.flush(60)

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — the name of the user with the producer role who has access to the topic;
   • <password> — user password;
   • <path> — the full path to the root certificate;
   • <topic_name> — topic name.

Python (kafka-python)

1. Download the root certificate and place it in the ~/.kafka/ folder:

   mkdir -p ~/.kafka/
   wget https://storage.dbaas.selcloud.ru/CA.pem -O ~/.kafka/root.crt
   chmod 0600 ~/.kafka/root.crt

2. Install the kafka-python library:

   pip install kafka-python

3. Use the connection example for the concumer:

   import kafka
   
   consumer = kafka.KafkaConsumer(
       "<topic_name>",
       bootstrap_servers="<host>:<port>",
       security_protocol="SASL_SSL",
       sasl_mechanism="SCRAM-SHA-512",
       ssl_cafile="<path>",
       sasl_plain_username="<user_name>",
       sasl_plain_password="<password>",
   )
   for record in consumer:
       print(record)

   Specify:

   • <topic_name> — topic name
   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <path> — the full path to the root certificate;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password.

4. Use the connection example for the producer:

   import kafka
   
   producer = kafka.KafkaProducer(
       bootstrap_servers="<host>:<port>",
       security_protocol="SASL_SSL",
       sasl_mechanism="SCRAM-SHA-512",
       ssl_cafile="<path>",
       sasl_plain_username="<user_name>",
       sasl_plain_password="<password>",
   )
   future = producer.send(
       topic="<topic_name>",
       value=b"message",
   )
   result = future.get(timeout=60)
   print(result)

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <path> — the full path to the root certificate;
   • <user_name> — the name of the user with the producer role who has access to the topic;
   • <password> — user password;
   • <topic_name> — topic name.

Go

1. Download the root certificate and place it in the ~/.kafka/ folder:

   mkdir -p ~/.kafka/
   wget https://storage.dbaas.selcloud.ru/CA.pem -O ~/.kafka/root.crt
   chmod 0600 ~/.kafka/root.crt

2. Create the file scram.go:

   scram.go

   package main
   
   import (
       "crypto/sha256"
       "crypto/sha512"
   
       "github.com/xdg-go/scram"
   )
   
   var (
       SHA256 scram.HashGeneratorFcn = sha256.New
       SHA512 scram.HashGeneratorFcn = sha512.New
   )
   
   type XDGSCRAMClient struct {
       *scram.Client
       *scram.ClientConversation
       scram.HashGeneratorFcn
   }
   
   func (x *XDGSCRAMClient) Begin(userName, password, authzID string) (err error) {
       x.Client, err = x.HashGeneratorFcn.NewClient(userName, password, authzID)
       if err != nil {
           return err
       }
       x.ClientConversation = x.Client.NewConversation()
       return nil
   }
   
   func (x *XDGSCRAMClient) Step(challenge string) (response string, err error) {
       response, err = x.ClientConversation.Step(challenge)
       return
   }
   
   func (x *XDGSCRAMClient) Done() bool {
       return x.ClientConversation.Done()
   }

3. Use the connection example for the concumer:

   package main
   
   import (
       "crypto/tls"
       "crypto/x509"
       "fmt"
       "io/ioutil"
       "os"
       "os/signal"
       "strings"
   
       "github.com/IBM/sarama"
   )
   
   const BROKERS = "<host>:<port>"
   const USER = "<user_name>"
   const PASSWORD = "<password>"
   const TOPIC = "<topic_name>"
   const CERT = "<path>"
   
   func main() {
       brokers := BROKERS
       splitBrokers := strings.Split(brokers, ",")
       conf := sarama.NewConfig()
       conf.Producer.RequiredAcks = sarama.WaitForAll
       conf.Version = sarama.V3_3_1_0
       conf.Consumer.Return.Errors = true
       conf.ClientID = "go_client"
       conf.Metadata.Full = true
       conf.Net.SASL.Enable = true
       conf.Net.SASL.User = USER
       conf.Net.SASL.Password = PASSWORD
       conf.Net.SASL.Handshake = true
       conf.Net.SASL.SCRAMClientGeneratorFunc = func() sarama.SCRAMClient {
           return &XDGSCRAMClient{HashGeneratorFcn: SHA512}
       }
       conf.Net.SASL.Mechanism = sarama.SASLMechanism(sarama.SASLTypeSCRAMSHA512)
   
       certs := x509.NewCertPool()
       pemPath := CERT
       pemData, err := ioutil.ReadFile(pemPath)
       if err != nil {
           fmt.Println("Couldn't load cert: ", err.Error())
           panic(err)
       }
       certs.AppendCertsFromPEM(pemData)
   
       conf.Net.TLS.Enable = true
       conf.Net.TLS.Config = &tls.Config{
           RootCAs: certs,
       }
   
       master, err := sarama.NewConsumer(splitBrokers, conf)
       if err != nil {
           fmt.Println("Couldn't create consumer: ", err.Error())
           panic(err)
       }
   
       defer func() {
           if err := master.Close(); err != nil {
               panic(err)
           }
       }()
   
       consumer, err := master.ConsumePartition(TOPIC, 0, sarama.OffsetOldest)
       if err != nil {
           panic(err)
       }
   
       signals := make(chan os.Signal, 1)
       signal.Notify(signals, os.Interrupt)
   
       doneCh := make(chan struct{})
       go func() {
           for {
               select {
               case err := <-consumer.Errors():
                   fmt.Println(err)
               case msg := <-consumer.Messages():
                   fmt.Println("Received messages", string(msg.Key), string(msg.Value))
               case <-signals:
                   doneCh <- struct{}{}
               }
           }
       }()
   
       <-doneCh
   }

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password;
   • <topic_name> — topic name;
   • <path> — the full path to the root certificate.

4. Use the connection example for the producer:

   package main
   
   import (
       "crypto/tls"
       "crypto/x509"
       "fmt"
       "io/ioutil"
       "strings"
   
       "github.com/IBM/sarama"
   )
   
   const BROKERS = "<host>:<port>"
   const USER = "<user_name>"
   const PASSWORD = "<password>"
   const TOPIC = "<topic_name>"
   const CERT = "<path>"
   
   func main() {
       brokers := BROKERS
       splitBrokers := strings.Split(brokers, ",")
       conf := sarama.NewConfig()
       conf.Producer.RequiredAcks = sarama.WaitForAll
       conf.Producer.Return.Successes = true
       conf.Version = sarama.V3_3_1_0
       conf.ClientID = "go_client"
       conf.Net.SASL.Enable = true
       conf.Net.SASL.Handshake = true
       conf.Net.SASL.User = USER
       conf.Net.SASL.Password = PASSWORD
       conf.Net.SASL.SCRAMClientGeneratorFunc = func() sarama.SCRAMClient {
           return &XDGSCRAMClient{HashGeneratorFcn: SHA512}
       }
       conf.Net.SASL.Mechanism = sarama.SASLMechanism(sarama.SASLTypeSCRAMSHA512)
   
       certs := x509.NewCertPool()
       pemPath := CERT
       pemData, err := ioutil.ReadFile(pemPath)
       if err != nil {
           fmt.Println("Couldn't load cert: ", err.Error())
           panic(err)
       }
       certs.AppendCertsFromPEM(pemData)
   
       conf.Net.TLS.Enable = true
       conf.Net.TLS.Config = &tls.Config{
           RootCAs: certs,
       }
   
       syncProducer, err := sarama.NewSyncProducer(splitBrokers, conf)
       if err != nil {
           fmt.Println("Couldn't create producer: ", err.Error())
           panic(err)
       }
   
       msg := &sarama.ProducerMessage{
           Topic: TOPIC,
           Value: sarama.StringEncoder("message"),
       }
       _, _, err = syncProducer.SendMessage(msg)
       if err != nil {
           fmt.Println("Couldn't send message: ", err.Error())
           panic(err)
       }
   }

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password;
   • <topic_name> — topic name;
   • <path> — the full path to the root certificate.

Node.js

1. Download the root certificate and place it in the ~/.kafka/ folder:

   mkdir -p ~/.kafka/
   wget https://storage.dbaas.selcloud.ru/CA.pem -O ~/.kafka/root.crt
   chmod 0600 ~/.kafka/root.crt

2. Install the kafkajs library:

   npm install kafkajs

3. Use the connection example for the concumer:

   const fs = require('fs');
   const { Kafka } = require('kafkajs');
   
   const config = {
     brokers: ['<host>:<port>'],
     ssl: {
       ca: [fs.readFileSync('<path>', 'utf-8')],
     },
     sasl: {
       mechanism: 'scram-sha-512',
       username: '<user_name>',
       password: '<password>',
     },
   };
   
   const kafka = new Kafka(config);
   const consumer = kafka.consumer({ groupId: 'example' });
   
   const run = async () => {
     await consumer.connect();
     await consumer.subscribe({
       topic: '<topic_name>',
       fromBeginning: true,
     });
   
     await consumer.run({
       eachMessage: async ({ message }) => {
        console.log({ value: message.value.toString() });
       },
     });
   };
   
   run();

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password;
   • <path> — the full path to the root certificate;
   • <topic_name> — topic name.

4. Use the connection example for the producer:

   const fs = require('fs');
   const { Kafka } = require('kafkajs');
   
   const config = {
     brokers: ['<host>:<port>'],
     ssl: {
       ca: [fs.readFileSync('<path>', 'utf-8')],
     },
     sasl: {
       mechanism: 'scram-sha-512',
       username: '<user_name>',
       password: '<password>',
     },
   };
   
   const kafka = new Kafka(config);
   const producer = kafka.producer();
   
   const run = async () => {
     await producer.connect();
     await producer.send({
       topic: '<topic_name>',
       messages: [{ value: 'message' }],
     });
     await producer.disconnect();
   };
   
   run();

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <path> — the full path to the root certificate;
   • <user_name> — the name of the user with the producer role who has access to the topic;
   • <password> — user password;
   • <topic_name> — topic name.

Java

1. Download the root certificate and place it in the ~/.kafka/ folder:

   mkdir -p ~/.kafka/
   wget https://storage.dbaas.selcloud.ru/CA.pem -O ~/.kafka/root.crt
   chmod 0600 ~/.kafka/root.crt

2. Navigate to the directory where the Java certificate store will be located:

   cd /etc/security

3. Add the SSL certificate to the Java trusted certificate store (Java Key Store):

   keytool \
   -importcert \
   -alias RootCA \
   -file ~/.kafka/root.crt \
   -keystore ssl \
   -storepass <keystore password> \
   -noprompt

   Specify <keystore_password> -keystore password for additional security.

4. Create a configuration file for Maven:

   pom.xml

   <?xml version="1.0" encoding="UTF-8"?>
   <project xmlns="http://maven.apache.org/POM/4.0.0"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
       <modelVersion>4.0.0</modelVersion>
       <groupId>com.example</groupId>
       <artifactId>app</artifactId>
       <packaging>jar</packaging>
       <version>1.0</version>
       <properties>
           <maven.compiler.source>1.8</maven.compiler.source>
           <maven.compiler.target>1.8</maven.compiler.target>
       </properties>
       <dependencies>
           <dependency>
               <groupId>org.slf4j</groupId>
               <artifactId>slf4j-simple</artifactId>
               <version>2.0.7</version>
           </dependency>
           <dependency>
               <groupId>com.fasterxml.jackson.core</groupId>
               <artifactId>jackson-databind</artifactId>
               <version>2.14.2</version>
           </dependency>
           <dependency>
               <groupId>org.apache.kafka</groupId>
               <artifactId>kafka-clients</artifactId>
               <version>3.4.0</version>
           </dependency>
       </dependencies>
       <build>
           <finalName>${project.artifactId}-${project.version}</finalName>
           <sourceDirectory>src</sourceDirectory>
           <resources>
               <resource>
                   <directory>src</directory>
               </resource>
           </resources>
           <plugins>
               <plugin>
                   <groupId>org.apache.maven.plugins</groupId>
                   <artifactId>maven-assembly-plugin</artifactId>
                   <executions>
                       <execution>
                           <goals>
                               <goal>attached</goal>
                           </goals>
                           <phase>package</phase>
                           <configuration>
                               <descriptorRefs>
                                   <descriptorRef>jar-with-dependencies</descriptorRef>
                               </descriptorRefs>
                               <archive>
                                   <manifest>
                                       <mainClass>com.example.App</mainClass>
                                   </manifest>
                               </archive>
                           </configuration>
                       </execution>
                   </executions>
               </plugin>
               <plugin>
                   <groupId>org.apache.maven.plugins</groupId>
                   <artifactId>maven-jar-plugin</artifactId>
                   <version>3.1.0</version>
                   <configuration>
                       <archive>
                           <manifest>
                               <mainClass>com.example.App</mainClass>
                           </manifest>
                       </archive>
                   </configuration>
               </plugin>
           </plugins>
       </build>
   </project>

5. Use the connection example for the concumer:

   src/com/example/App.java

   package com.example;
   
   import java.util.*;
   import org.apache.kafka.common.*;
   import org.apache.kafka.common.serialization.StringDeserializer;
   import org.apache.kafka.clients.consumer.*;
   
   public class App {
       private static final String HOST = "<host>:<port>";
       private static final String TOPIC = "<topic_name>";
       private static final String USER = "<user_name>";
       private static final String PASSWORD = "<password>";
       private static final String TS_FILE = "/etc/security/ssl";
       private static final String TS_PASSWORD = "<keystore_password>";
   
       public static void main(String[] args) {
           String jaasCfg = String.format("org.apache.kafka.common.security.scram.ScramLoginModule required username=\"%s\" password=\"%s\";", USER, PASSWORD);
   
           String deserializer = StringDeserializer.class.getName();
           Properties props = new Properties();
           props.put("bootstrap.servers", HOST);
           props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
           props.put("group.id", "example");
           props.put("key.deserializer", deserializer);
           props.put("value.deserializer", deserializer);
           props.put("security.protocol", "SASL_SSL");
           props.put("sasl.mechanism", "SCRAM-SHA-512");
           props.put("sasl.jaas.config", jaasCfg);
           props.put("ssl.truststore.location", TS_FILE);
           props.put("ssl.truststore.password", TS_PASSWORD);
   
           Consumer<String, String>consumer = new KafkaConsumer<>(props);
           consumer.subscribe(Arrays.asList(new String[] {TOPIC}));
   
           while (true) {
               ConsumerRecords<String, String> records = consumer.poll(100);
               for (ConsumerRecord<String, String> record: records) {
                   System.out.println(record.value());
               }
           }
       }
   }

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <topic_name> — topic name;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password;
   • <keystore_password> — keystore password.

6. Use the connection example for the producer:

   src/com/example/App.java

   package com.example;
   
   import java.util.*;
   import org.apache.kafka.common.*;
   import org.apache.kafka.common.serialization.StringSerializer;
   import org.apache.kafka.clients.producer.*;
   
   public class App {
       private static final String HOST = "<host>:<port>";
       private static final String TOPIC = "<topic_name>";
       private static final String USER = "<user_name>";
       private static final String PASSWORD = "<password>";
       private static final String TS_FILE = "/etc/security/ssl";
       private static final String TS_PASSWORD = "<keystore_password>";
   
       public static void main(String[] args) {
           String jaasCfg = String.format("org.apache.kafka.common.security.scram.ScramLoginModule required username=\"%s\" password=\"%s\";", USER, PASSWORD);
   
           String serializer = StringSerializer.class.getName();
           Properties props = new Properties();
           props.put("bootstrap.servers", HOST);
           props.put("acks", "all");
           props.put("key.serializer", serializer);
           props.put("value.serializer", serializer);
           props.put("security.protocol", "SASL_SSL");
           props.put("sasl.mechanism", "SCRAM-SHA-512");
           props.put("sasl.jaas.config", jaasCfg);
           props.put("ssl.truststore.location", TS_FILE);
           props.put("ssl.truststore.password", TS_PASSWORD);
   
           Producer<String, String> producer = new KafkaProducer<>(props);
           try {
               producer.send(new ProducerRecord<String, String>(TOPIC, "key", "message")).get();
               producer.flush();
               producer.close();
           } catch (Exception ex) {
               System.out.println(ex);
               producer.close();
           }
       }
   }

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <topic_name> — topic name;
   • <user_name> — the name of the user with the producer role who has access to the topic;
   • <password> — user password;
   • <keystore_password> — certificate password.

7. Build and run the application:

   mvn clean package
   java -jar target/app-1.0-jar-with-dependencies.jar

Connect without SSL

Bash

1. Open the CLI.

2. Use the connection example for the concumer:

   kcat -C \
   -b <host>:<port> \
   -t <topic_name> \
   -X sasl.username=<user_name> \
   -X sasl.password=<password> \
   -X security.protocol=SASL_PLAINTEXT \
   -X sasl.mechanisms=SCRAM-SHA-512

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <topic_name> — topic name;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password.

3. Use the connection example for the producer:

   kcat -P \
   -b <host>:<port> \
   -t <topic_name> \
   -X sasl.username=<user_name> \
   -X sasl.password=<password> \
   -X security.protocol=SASL_PLAINTEXT \
   -X sasl.mechanisms=SCRAM-SHA-512

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <topic_name> — topic name;
   • <user_name> — the name of the user with the producer role who has access to the topic;
   • <password> — user password.

Python (confluent-kafka)

1. Install the confluent-kafka library:

   pip install confluent-kafka

2. Use the connection example for the concumer:

   import confluent_kafka
   
   def error_callback(err):
       raise err
   
   consumer = confluent_kafka.Consumer({
       "bootstrap.servers": "<host>:<port>",
       "security.protocol": "SASL_PLAINTEXT",
       "sasl.mechanism": "SCRAM-SHA-512",
       "sasl.username": "<user_name>",
       "sasl.password": "<password>",
       "group.id": "example",
       "auto.offset.reset": "earliest",
       "enable.auto.commit": False,
       "error_cb": error_callback,
   })
   
   consumer.subscribe(["<topic_name>"])
   
   while True:
       record = consumer.poll(timeout=1.0)
       if record is not None:
           if record.error():
               if record.error().code() == confluent_kafka.KafkaError._PARTITION_EOF:
                   print(f"{record.topic()} [{record.partition()}]: reached end at offset {record.offset()}")
               elif record.error():
                   raise confluent_kafka.KafkaException(record.error())
           else:
               print(record.value())
   
   consumer.close()

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password;
   • <topic_name> — topic name.

3. Use the connection example for the producer:

   import confluent_kafka
   
   def error_callback(err):
       raise err
   
   producer = confluent_kafka.Producer({
       "bootstrap.servers": "<host>:<port>",
       "security.protocol": "SASL_PLAINTEXT",
       "sasl.mechanism": "SCRAM-SHA-512",
       "sasl.username": "<user_name>",
       "sasl.password": "<password>",
       "error_cb": error_callback,
   })
   producer.produce("<topic_name>", "message")
   producer.flush(60)

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — database user name;
   • <password> — user password;
   • <topic_name> — topic name.

Python (kafka-python)

1. Install the kafka-python library:

   pip install kafka-python

2. Use the connection example for the concumer:

   import kafka
   
   consumer = kafka.KafkaConsumer(
       "<topic_name>",
       bootstrap_servers="<host>:<port>",
       security_protocol="SASL_PLAINTEXT",
       sasl_mechanism="SCRAM-SHA-512",
       sasl_plain_username="<user_name>",
       sasl_plain_password="<password>",
   )
   for record in consumer:
       print(record)

   Specify:

   • <topic_name> — topic name
   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password.

3. Use the connection example for the producer:

   import kafka
   
   producer = kafka.KafkaProducer(
       bootstrap_servers="<host>:<port>",
       security_protocol="SASL_PLAINTEXT",
       sasl_mechanism="SCRAM-SHA-512",
       sasl_plain_username="<user_name>",
       sasl_plain_password="<password>",
   )
   future = producer.send(
       topic="<topic_name>",
       value=b"message",
   )
   result = future.get(timeout=60)
   print(result)

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — database user name;
   • <password> — user password;
   • <topic_name> — topic name.

Go

1. Create the file scram.go:

   scram.go

   package main
   
   import (
       "crypto/sha256"
       "crypto/sha512"
   
       "github.com/xdg-go/scram"
   )
   
   var (
       SHA256 scram.HashGeneratorFcn = sha256.New
       SHA512 scram.HashGeneratorFcn = sha512.New
   )
   
   type XDGSCRAMClient struct {
       *scram.Client
       *scram.ClientConversation
       scram.HashGeneratorFcn
   }
   
   func (x *XDGSCRAMClient) Begin(userName, password, authzID string) (err error) {
       x.Client, err = x.HashGeneratorFcn.NewClient(userName, password, authzID)
       if err != nil {
           return err
       }
       x.ClientConversation = x.Client.NewConversation()
       return nil
   }
   
   func (x *XDGSCRAMClient) Step(challenge string) (response string, err error) {
       response, err = x.ClientConversation.Step(challenge)
       return
   }
   
   func (x *XDGSCRAMClient) Done() bool {
       return x.ClientConversation.Done()
   }

2. Use the connection example for the concumer:

   package main
   
   import (
       "fmt"
       "os"
       "os/signal"
       "strings"
   
       "github.com/IBM/sarama"
   )
   
   const BROKERS = "<host>:<port>"
   const USER = "<user_name>"
   const PASSWORD = "<password>"
   const TOPIC = "<topic_name>"
   
   func main() {
       brokers := BROKERS
       splitBrokers := strings.Split(brokers, ",")
       conf := sarama.NewConfig()
       conf.Producer.RequiredAcks = sarama.WaitForAll
       conf.Version = sarama.V3_3_1_0
       conf.Consumer.Return.Errors = true
       conf.ClientID = "go_client"
       conf.Metadata.Full = true
       conf.Net.SASL.Enable = true
       conf.Net.SASL.User = USER
       conf.Net.SASL.Password = PASSWORD
       conf.Net.SASL.Handshake = true
       conf.Net.SASL.SCRAMClientGeneratorFunc = func() sarama.SCRAMClient {
           return &XDGSCRAMClient{HashGeneratorFcn: SHA512}
       }
       conf.Net.SASL.Mechanism = sarama.SASLMechanism(sarama.SASLTypeSCRAMSHA512)
       conf.Net.TLS.Enable = false
   
       master, err := sarama.NewConsumer(splitBrokers, conf)
       if err != nil {
           fmt.Println("Couldn't create consumer: ", err.Error())
           panic(err)
       }
   
       defer func() {
           if err := master.Close(); err != nil {
               panic(err)
           }
       }()
   
       consumer, err := master.ConsumePartition(TOPIC, 0, sarama.OffsetOldest)
       if err != nil {
           panic(err)
       }
   
       signals := make(chan os.Signal, 1)
       signal.Notify(signals, os.Interrupt)
   
       doneCh := make(chan struct{})
       go func() {
           for {
               select {
               case err := <-consumer.Errors():
                   fmt.Println(err)
               case msg := <-consumer.Messages():
                   fmt.Println("Received messages", string(msg.Key), string(msg.Value))
               case <-signals:
                   doneCh <- struct{}{}
               }
           }
       }()
   
       <-doneCh
   }

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password;
   • <topic_name> — topic name.

3. Use the connection example for the producer:

   package main
   
   import (
       "fmt"
       "strings"
   
       "github.com/IBM/sarama"
   )
   
   const BROKERS = "<host>:<port>"
   const USER = "<user_name>"
   const PASSWORD = "<password>"
   const TOPIC = "<topic_name>"
   
   func main() {
       brokers := BROKERS
       splitBrokers := strings.Split(brokers, ",")
       conf := sarama.NewConfig()
       conf.Producer.RequiredAcks = sarama.WaitForAll
       conf.Producer.Return.Successes = true
       conf.Version = sarama.V3_3_1_0
       conf.ClientID = "go_client"
       conf.Net.SASL.Enable = true
       conf.Net.SASL.Handshake = true
       conf.Net.SASL.User = USER
       conf.Net.SASL.Password = PASSWORD
       conf.Net.SASL.SCRAMClientGeneratorFunc = func() sarama.SCRAMClient {
           return &XDGSCRAMClient{HashGeneratorFcn: SHA512}
       }
       conf.Net.SASL.Mechanism = sarama.SASLMechanism(sarama.SASLTypeSCRAMSHA512)
       conf.Net.TLS.Enable = false
   
       syncProducer, err := sarama.NewSyncProducer(splitBrokers, conf)
       if err != nil {
           fmt.Println("Couldn't create producer: ", err.Error())
           panic(err)
       }
   
       msg := &sarama.ProducerMessage{
           Topic: TOPIC,
           Value: sarama.StringEncoder("message"),
       }
       _, _, err = syncProducer.SendMessage(msg)
       if err != nil {
           fmt.Println("Couldn't send message: ", err.Error())
           panic(err)
       }
   }

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password;
   • <topic_name> — topic name.

Node.js

1. Install the kafkajs library:

   npm install kafkajs

2. Use the connection example for the concumer:

   const { Kafka } = require('kafkajs');
   
   const config = {
     brokers: ['<host>:<port>'],
     ssl: false,
     sasl: {
       mechanism: 'scram-sha-512',
       username: '<user_name>',
       password: '<password>',
     },
   };
   
   const kafka = new Kafka(config);
   const consumer = kafka.consumer({ groupId: 'example' });
   
   const run = async () => {
     await consumer.connect();
     await consumer.subscribe({
       topic: '<topic_name>',
       fromBeginning: true,
     });
   
     await consumer.run({
       eachMessage: async ({ message }) => {
         console.log({ value: message.value.toString() });
       },
     });
   };
   
   run();

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password;
   • <topic_name> — topic name.

3. Use the connection example for the producer:

   const { Kafka } = require('kafkajs');
   
   const config = {
     brokers: ['<host>:<port>'],
     ssl: false,
     sasl: {
       mechanism: 'scram-sha-512',
       username: '<user_name>',
       password: '<password>',
     },
   };
   
   const kafka = new Kafka(config);
   const producer = kafka.producer();
   
   const run = async () => {
     await producer.connect();
     await producer.send({
       topic: '<topic_name>',
       messages: [{ value: 'message' }],
     });
     await producer.disconnect();
   };
   
   run();

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <user_name> — database user name;
   • <password> — user password;
   • <topic_name> — topic name.

Java

1. Create a configuration file for Maven:

   pom.xml

   <?xml version="1.0" encoding="UTF-8"?>
   <project xmlns="http://maven.apache.org/POM/4.0.0"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
       <modelVersion>4.0.0</modelVersion>
       <groupId>com.example</groupId>
       <artifactId>app</artifactId>
       <packaging>jar</packaging>
       <version>1.0</version>
       <properties>
           <maven.compiler.source>1.8</maven.compiler.source>
           <maven.compiler.target>1.8</maven.compiler.target>
       </properties>
       <dependencies>
           <dependency>
               <groupId>org.slf4j</groupId>
               <artifactId>slf4j-simple</artifactId>
               <version>2.0.7</version>
           </dependency>
           <dependency>
               <groupId>com.fasterxml.jackson.core</groupId>
               <artifactId>jackson-databind</artifactId>
               <version>2.14.2</version>
           </dependency>
           <dependency>
               <groupId>org.apache.kafka</groupId>
               <artifactId>kafka-clients</artifactId>
               <version>3.4.0</version>
           </dependency>
       </dependencies>
       <build>
           <finalName>${project.artifactId}-${project.version}</finalName>
           <sourceDirectory>src</sourceDirectory>
           <resources>
               <resource>
                   <directory>src</directory>
               </resource>
           </resources>
           <plugins>
               <plugin>
                   <groupId>org.apache.maven.plugins</groupId>
                   <artifactId>maven-assembly-plugin</artifactId>
                   <executions>
                       <execution>
                           <goals>
                               <goal>attached</goal>
                           </goals>
                           <phase>package</phase>
                           <configuration>
                               <descriptorRefs>
                                   <descriptorRef>jar-with-dependencies</descriptorRef>
                               </descriptorRefs>
                               <archive>
                                   <manifest>
                                       <mainClass>com.example.App</mainClass>
                                   </manifest>
                               </archive>
                           </configuration>
                       </execution>
                   </executions>
               </plugin>
               <plugin>
                   <groupId>org.apache.maven.plugins</groupId>
                   <artifactId>maven-jar-plugin</artifactId>
                   <version>3.1.0</version>
                   <configuration>
                       <archive>
                           <manifest>
                               <mainClass>com.example.App</mainClass>
                           </manifest>
                       </archive>
                   </configuration>
               </plugin>
           </plugins>
       </build>
   </project>

2. Use the connection example for the concumer:

   src/com/example/App.java

   package com.example;
   
   import java.util.*;
   import org.apache.kafka.common.*;
   import org.apache.kafka.common.serialization.StringDeserializer;
   import org.apache.kafka.clients.consumer.*;
   
   public class App {
       private static final String HOST = "<host>:<port>";
       private static final String TOPIC = "<topic_name>";
       private static final String USER = "<user_name>";
       private static final String PASSWORD = "<password>";
   
       public static void main(String[] args) {
           String jaasCfg = String.format("org.apache.kafka.common.security.scram.ScramLoginModule required username=\"%s\" password=\"%s\";", USER, PASSWORD);
   
           String deserializer = StringDeserializer.class.getName();
           Properties props = new Properties();
           props.put("bootstrap.servers", HOST);
           props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
           props.put("group.id", "example");
           props.put("key.deserializer", deserializer);
           props.put("value.deserializer", deserializer);
           props.put("security.protocol", "SASL_PLAINTEXT");
           props.put("sasl.mechanism", "SCRAM-SHA-512");
           props.put("sasl.jaas.config", jaasCfg);
   
           Consumer<String, String>consumer = new KafkaConsumer<>(props);
           consumer.subscribe(Arrays.asList(new String[] {TOPIC}));
   
           while (true) {
               ConsumerRecords<String, String> records = consumer.poll(100);
               for (ConsumerRecord<String, String> record: records) {
                   System.out.println(record.value());
               }
           }
       }
   }

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <topic_name> — topic name;
   • <user_name> — the name of the user with the role of concumer who has access to the topic;
   • <password> — user password.

3. Use the connection example for the producer:

   src/com/example/App.java

   package com.example;
   
   import java.util.*;
   import org.apache.kafka.common.*;
   import org.apache.kafka.common.serialization.StringSerializer;
   import org.apache.kafka.clients.producer.*;
   
   public class App {
       private static final String HOST = "<host>:<port>";
       private static final String TOPIC = "<topic_name>";
       private static final String USER = "<user_name>";
       private static final String PASSWORD = "<password>";
   
       public static void main(String[] args) {
           String jaasCfg = String.format("org.apache.kafka.common.security.scram.ScramLoginModule required username=\"%s\" password=\"%s\";", USER, PASSWORD);
   
           String serializer = StringSerializer.class.getName();
           Properties props = new Properties();
           props.put("bootstrap.servers", HOST);
           props.put("acks", "all");
           props.put("key.serializer", serializer);
           props.put("value.serializer", serializer);
           props.put("security.protocol", "SASL_PLAINTEXT");
           props.put("sasl.mechanism", "SCRAM-SHA-512");
           props.put("sasl.jaas.config", jaasCfg);
   
           Producer<String, String> producer = new KafkaProducer<>(props);
           try {
               producer.send(new ProducerRecord<String, String>(TOPIC, "key", "message")).get();
               producer.flush();
               producer.close();
           } catch (Exception ex) {
               System.out.println(ex);
               producer.close();
           }
       }
   }

   Specify:

   • <host> — DNS address of the node;
   • <port> — port for connection;
   • <topic_name> — topic name;
   • <user_name> — database user name;
   • <password> — user password.

4. Build and run the application:

   mvn clean package
   java -jar target/app-1.0-jar-with-dependencies.jar