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Table of Contents

Introduction

Kafka Connect allows you to continuously ingest data from external systems into Kafka via connect sources and write data from Kafka to external system via connect sinks.

Various plugins are available for a variety of different data sources and data sinks.

Confluent Plugins

Camel Plugins

Debezium Plugins

Single Message Transformations (SMTs) are applied to messages as they flow through Connect. 

Connect Demo

Postgres JDBC Sink Connector (Confluent)

Prepare the connector image

Download the JDBC sink connector from JDBC Connector (Source and Sink)

Create a docker file for this connector

Code Block
languagetext
titleDocker
FROM quay.io/strimzi/kafka:0.32.0-kafka-3.3.1
USER root:root
RUN mkdir -p /opt/kafka/plugins/jdbc
COPY ./confluentinc-kafka-connect-jdbc-10.6.0.zip /opt/kafka/plugins/j
dbc/
RUN unzip /opt/kafka/plugins/jdbc/confluentinc-kafka-connect-jdbc-10.6.0.zip -d /opt/kafka/plugins/jdbc
RUN rm /opt/kafka/plugins/jdbc/confluentinc-kafka-connect-jdbc-10.6.0.zip
USER 1001

Build the image and copy it to your docker repository

docker build -f Dockerfile . t ktimoney/strimzi connector

Prepare the postges database

Setup a new username/password and schema for Kafka connect to write to

...

languagetext
titlePostgres

...

Table of Contents

Introduction

Kafka Connect allows you to continuously ingest data from external systems into Kafka via connect sources and write data from Kafka to external system via connect sinks.

Various plugins are available for a variety of different data sources and data sinks.

Confluent Plugins

Camel Plugins

Debezium Plugins

Single Message Transformations (SMTs) are applied to messages as they flow through Connect. 


Connect Demo

Postgres JDBC Sink Connector (Confluent)

Prepare the connector image

Download the JDBC sink connector from JDBC Connector (Source and Sink)

Create a docker file for this connector


Code Block
languagetext
titleDocker
FROM quay.io/strimzi/kafka:0.32.0-kafka-3.3.1
USER root:root
RUN mkdir -p /opt/kafka/plugins/jdbc
COPY ./confluentinc-kafka-connect-jdbc-10.6.0.zip /opt/kafka/plugins/j
dbc/
RUN unzip /opt/kafka/plugins/jdbc/confluentinc-kafka-connect-jdbc-10.6.0.zip -d /opt/kafka/plugins/jdbc
RUN rm /opt/kafka/plugins/jdbc/confluentinc-kafka-connect-jdbc-10.6.0.zip
USER 1001

Build the image and copy it to your docker repository

docker build -f Dockerfile . t ktimoney/strimzi connector


Prepare the postges database

Setup a new username/password and schema for Kafka connect to write to

Code Block
languagetext
titlePostgres
    SELECT 'CREATE DATABASE kafka'
    WHERE NOT EXISTS (SELECT FROM pg_userdatabase WHERE  usenamedatname = 'kafka')\gexec
THEN    DO $$
    BEGIN
      IF NOT EXISTS (SELECT FROM pg_user WHERE  usename = 'kafka') THEN
         CREATE USER kafka WITH PASSWORD 'kafka';
         GRANT ALL PRIVILEGES ON DATABASE kafka TO kafka;
      END IF;
    END
    $$;

...

The database connection details are also included.


Influxdb Sink Connector (Apache Camel)

Prepare the connector image

Download the Influxdb connector: wget https://repo.maven.apache.org/maven2/org/apache/camel/kafkaconnector/camel-influxdb-kafka-connector/0.8.0/camel-influxdb-kafka-connector-0.8.0-package.tar.gz

Create a docker file for this connector

Code Block
languagetext
titleDocker
FROM quay.io/strimzi/kafka:0.22.1-kafka-2.7.0
USER root:root 
RUN mkdir -p /opt/kafka/plugins/camel
COPY ./camel-influxdb-kafka-connector-0.8.0-package.tar.gz /opt/kafka/plugins/camel/
RUN tar -xvzf /opt/kafka/plugins/camel/camel-influxdb-kafka-connector-0.8.0-package.tar.gz --directory /opt/kafka/plugins/camel
RUN rm /opt/kafka/plugins/camel/camel-influxdb-kafka-connector-0.8.0-package.tar.gz 
USER 1001

Build the image and copy it to your docker repository

docker build -f Dockerfile . t ktimoney/strimzi_influxdb_connector

Prepare the message producer

In this example we are going to deserialize the value to json, we can do this without using a schema.

They will take the following format:

Code Block
languagejs
titleSchema & Payload
{
"camelInfluxDB.MeasurementName":"disk_space"
"time":"2023-01-23T13:03:31Z"
"host":"localhost"
"region":"IE-region"
"used":"19%"
"free":"81%"
}

The important thing to note here is that one of the "keys" has to be "camelInfluxDB.MeasurementName", this is required by the camel transformer when converting into an influxdb point object.

The above structure can be represented in golang using the following struct:

...

languagetext
titleGo Structs

...

.gz

Create a docker file for this connector


Code Block
languagetext
titleDocker
FROM quay.io/strimzi/kafka:0.22.1-kafka-2.7.0
USER root:root 
RUN mkdir -p /opt/kafka/plugins/camel
COPY ./camel-influxdb-kafka-connector-0.8.0-package.tar.gz /opt/kafka/plugins/camel/
RUN tar -xvzf /opt/kafka/plugins/camel/camel-influxdb-kafka-connector-0.8.0-package.tar.gz --directory /opt/kafka/plugins/camel
RUN rm /opt/kafka/plugins/camel/camel-influxdb-kafka-connector-0.8.0-package.tar.gz 
USER 1001

Build the image and copy it to your docker repository

docker build -f Dockerfile . t ktimoney/strimzi_influxdb_connector



Prepare the message producer

In this example we are going to deserialize the value to json, we can do this without using a schema.

They will take the following format:

Code Block
languagejs
titleSchema & Payload
{
"camelInfluxDB.MeasurementName":"disk_space"
"time":"2023-01-23T13:03:31Z"
"host":"localhost"
"region":"IE-region"
"used":"19%"
"free":"81%"
}

The important thing to note here is that one of the "keys" has to be "camelInfluxDB.MeasurementName", this is required by the camel transformer when converting into an influxdb point object.


The above structure can be represented in golang using the following struct:

Code Block
languagetext
titleGo Structs
type InfluxPayload struct {
        Measurement string `json:"camelInfluxDB.MeasurementName"`
        Time        string `json:"time"`
        Host   string `json:"host"`
        Region string `json:"region"`
        Used   string `json:"used"`
        Free   string `json:"free"`
}



Create the KafkaConnect object

Code Block
languagetext
titleKafkaConnect
apiVersion: kafka.strimzi.io/v1beta1
kind: KafkaUser
metadata:
  name: connect
  namespace: kafka
  labels:
    strimzi.io/cluster: my-cluster
spec:
  authentication:
    type: tls
---
apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnect
metadata:
  name: my-connect-cluster
  namespace: kafka
  annotations:
  # use-connector-resources configures this KafkaConnect
  # to use KafkaConnector resources to avoid
  # needing to call the Connect REST API directly
    strimzi.io/use-connector-resources: "true"
spec:   
  image: ktimoney/strimzi-influxdb-connect
  replicas: 1
  bootstrapServers: my-cluster-kafka-bootstrap:9093
  tls:
    trustedCertificates:
      - secretName: my-cluster-cluster-ca-cert
        certificate: ca.crt
      - secretName: my-cluster-clients-ca-cert
        certificate: ca.crt
  authentication:
    type: tls
    certificateAndKey:
      secretName: connect
      certificate: user.crt
      key: user.key
  config:
    group.id: connect-cluster
    offset.storage.topic: connect-cluster-offsets
    config.storage.topic: connect-cluster-configs
    status.storage.topic: connect-cluster-status
    config.storage.replication.factor: 1
    offset.storage.replication.factor: 1
    status.storage.replication.factor: 1


We are connecting to the 9093 tls port so we include required certificates in our configuration.

The image tag references the image we built earlier : ktimoney/strimzi-influx-connect


Create the Sink connector

Code Block
languagetext
titleKafkaConnector
apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnector
metadata:
  name: my-sink-connector
  namespace: kafka
  labels:
    strimzi.io/cluster: my-connect-cluster
spec:   class: org.apache.camel.kafkaconnector.influxdb.CamelInfluxdbSinkConnector
  tasksMax: 1
  config:
    topics: my-topic
    errors.deadletterqueue.topic.name: my-topic-dl
    errors.deadletterqueue.topic.replication.factor: 1
    key.converter: org.apache.kafka.connect.storage.StringConverter
    value.converter: org.apache.kafka.connect.json.JsonConverter 
    key.converter.schemas.enable: false
    value.converter.schemas.enable: false
    key.ignore: true
    auto.create: true
    camel.beans.influx: "#class:org.influxdb.InfluxDBFactory#connect('http://influxdb.default:8086', 'influxdb', 'influxdb')"
    camel.sink.path.connectionBean: influx
    camel.sink.endpoint.databaseName: ts_host_metrics
    camel.sink.endpoint.operation: insert
    camel.sink.endpoint.retentionPolicy: autogen


The KafkaConnector is configured to use the "org.apache.camel.kafkaconnector.influxdb.CamelInfluxdbSinkConnector" class.

The value converter is set to "org.apache.kafka.connect.json.JsonConverter".

The camel connector comes with a in built TypeConverter called CamelInfluxDbConverters which will read the json produced as a Map<String, Object> map) and return an Influxdb Point object.

The database connection details are specified in camel.beans.influx.

This sets up a connection bean to be used by camel.sink.path.connectionBean.

Note: It is important to wrap the camel.beans.influx parameter in quotes otherwise it will be treated as a comment.

The yaml for the influxdb pod is available here: influxdb.yaml


When the connector is running it will produce records to influxdb like the following:

Code Block
languagetext
titleInfluxDB query
{'pretty': 'true', 'db': 'ts_host_metrics', 'q': 'SELECT "region", "host", "free", "used" FROM "disk_space" WHERE "host"=\'localhost\''}
{
    "results": [
        {
            "statement_id": 0,
            "series": [
                {
                    "name": "disk_space",
                    "columns": [
                        "time",
                        "region",
                        "host",
                        "free",
                        "used"
                    ],
                    "values": [
                        [
                            "2023-01-23T13:03:32.1246436Z",
                          Measurement string `json:"camelInfluxDB.MeasurementName"`"IE-region",
                   Time        string `json:"time"`localhost",
             Host   string `json:"host"`         Region string `json:"region"`81%",
           Used   string `json:"used"`         Free   string `json:"free"`
}

Create the KafkaConnect object

Code Block
languagetext
titleKafkaConnect
apiVersion: kafka.strimzi.io/v1beta1
kind: KafkaUser
metadata:
  name: connect
  namespace: kafka
  labels:19%"
                        ]
     strimzi.io/cluster: my-cluster spec:   authentication:     type: tls --- apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnect
metadata: ]
    name: my-connect-cluster   namespace: kafka   annotations:   # use-connector-resources}
configures this KafkaConnect   # to use KafkaConnector resources to avoid ]
 # needing to call the Connect REST API}
directly     strimzi.io/use-connector-resources: "true"
spec:   
  image: ktimoney/strimzi-influxdb-connect
  replicas: 1
  bootstrapServers: my-cluster-kafka-bootstrap:9093
  tls:
    trustedCertificates:
      - secretName: my-cluster-cluster-ca-cert]
}


Minio Sink Connector (Apache Camel)

Prepare the connector image

Download the minio sink connector: wget https://repo.maven.apache.org/maven2/org/apache/camel/kafkaconnector/camel-file-kafka-connector/3.20.0/camel-file-kafka-connector-3.20.0-package.tar.gz


We need to create some custom classes:

CamelMinioConverters.java - this will allow us to deserialize to json and convert the hashmap to an inputstream

Code Block
languagejava
titleCamelMinioConverters
package com.custom.convert.minio;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.util.Map;
import org.apache.camel.Converter;

@Converter(generateLoader = true)
public final class CamelMinioConverters {

    private   certificate: ca.crtCamelMinioConverters() {
    }

 - secretName: my-cluster-clients-ca-cert
 @SuppressWarnings("deprecation")
    @Converter
  certificate: ca.crt public static authentication:
    type: tlsInputStream fromMapToInputStream(Map<String, Object> map) {

     certificateAndKey: String json = "{}";
  secretName: connect   try {
  certificate: user.crt     json = key: user.keynew ObjectMapper().writeValueAsString(map);
  config:    } group.id: connect-cluster
 catch (JsonProcessingException e) {
  offset.storage.topic: connect-cluster-offsets     config.storage.topic: connect-cluster-configs
 e.printStackTrace();
  status.storage.topic: connect-cluster-status   }
 config.storage.replication.factor: 1   return new offset.storage.replication.factor: 1ByteArrayInputStream(json.getBytes());
     status.storage.replication.factor: 1

We are connecting to the 9093 tls port so we include required certificates in our configuration.

The image tag references the image we built earlier : ktimoney/strimzi-influx-connect

...

}

}


StringAggregator.java - this will allow us to aggregate the messages and set the file name

{'pretty': 'true', 'db': 'ts_host_metrics', 'q': 'SELECT "region", "host", "free", "used" FROM "disk_space" WHERE "host"=\'localhost\''} { "results": [ { "statement_id": 0, "series": [ { "name": "disk_space", "columns": [ "time", "region", "host", "free", "used" ],
Code Block
Code Block
languagetext
titleInfluxDB query
languagetextjava
titleKafkaConnector
apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnector
metadata:
  name: my-sink-connector
  namespace: kafka
  labels:
    strimzi.io/cluster: my-connect-cluster
spec:   class: org.apache.camel.kafkaconnector.influxdb.CamelInfluxdbSinkConnector
  tasksMax: 1
  config:
    topics: my-topic
    errors.deadletterqueue.topic.name: my-topic-dl
    errors.deadletterqueue.topic.replication.factor: 1
    key.converter: org.apache.kafka.connect.storage.StringConverter
    value.converter: org.apache.kafka.connect.json.JsonConverter 
    key.converter.schemas.enable: false
    value.converter.schemas.enable: false
    key.ignore: true
    auto.create: true
    camel.beans.influx: "#class:org.influxdb.InfluxDBFactory#connect('http://influxdb.default:8086', 'influxdb', 'influxdb')"
    camel.sink.path.connectionBean: influx
    camel.sink.endpoint.databaseName: ts_host_metrics
    camel.sink.endpoint.operation: insert
    camel.sink.endpoint.retentionPolicy: autogen

The KafkaConnector is configured to use the "org.apache.camel.kafkaconnector.influxdb.CamelInfluxdbSinkConnector" class.

The value converter are set to "org.apache.kafka.connect.json.JsonConverter".

The camel connector comes with a in built TypeConverter called CamelInfluxDbConverters which will read the json produced as a Map<String, Object> map) and return an Influxdb Point object.

The database connection details are specified in camel.beans.influx.

This sets up a connection bean to be used by camel.sink.path.connectionBean.

Note: It is important to wrap the camel.beans.influx parameter in quotes otherwise it will be treated as a comment.

The yaml for the influxdb pod is available here: influxdb.yaml

When the connector is running it will produce records to influxdb like the following:

StringAggregator
package com.custom.aggregate.minio;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import org.apache.camel.AggregationStrategy;
import org.apache.camel.Exchange;
import org.apache.camel.Message;

public class CustomStringAggregator implements AggregationStrategy {

    //@Override
    public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
      Message newIn = newExchange.getIn();
      Map<String, String> keyMap = (HashMap) newIn.getHeaders().get("camel.kafka.connector.record.key");
      String key = keyMap.get("id");
      SimpleDateFormat sdf = new SimpleDateFormat("ddMMyy-hhmmss-SSS");              
      String fileName = "ExchangeKafka-" + key + "-" + sdf.format( new Date() ) + ".json";
      newIn.setHeader("file", fileName);               

     // lets append the old body to the new body
        if (oldExchange == null) {
            return newExchange;
        }

        String body = oldExchange.getIn().getBody(String.class);
        if (body != null) {
            String newBody = newIn.getBody(String.class);
            if (newBody != null) {
                body += System.lineSeparator() + newBody;
            }

            newIn.setBody(body);
        }
        return newExchange;
    }
}

We can then create a custom jar for our code and copy it into the docker container.

Note: You can also set the filename in the Kafka header using either CamelHeader.file or CamelHeader.ce-file


Create a docker file for this connector


Code Block
languagetext
titleDocker
FROM quay.io/strimzi/kafka:0.32.0-kafka-3.3.1
USER root:root
RUN mkdir -p /opt/kafka/plugins/camel
COPY ./camel-minio-sink-kafka-connector-3.20.0-package.tar.gz /opt/kafka/plugins/camel/
RUN tar -xvzf /opt/kafka/plugins/camel/camel-minio-sink-kafka-connector-3.20.0-package.tar.gz --directory /opt/kafka/plugins/camel
COPY ./custom-converter-1.0.0.jar /opt/kafka/plugins/camel/camel-minio-sink-kafka-connector/
RUN rm /opt/kafka/plugins/camel/camel-minio-sink-kafka-connector-3.20.0-package.tar.gzRUN rm -rf /opt/kafka/plugins/camel/docs
USER 1001

Build the image and copy it to your docker repository

docker build -f Dockerfile . t ktimoney/strimzi_minio_connector



Prepare the message producer

In this example we are going to deserialize the value to a string. (Same producer as the influxdb example)

They will take the following format:

Code Block
languagejs
titleSchema & Payload
{
"camelInfluxDB.MeasurementName":"disk_space"
"time":"2023-01-23T13:03:31Z"
"host":"localhost"
"region":"IE-region"
"used":"19%"
"free":"81%"
}

With the type converter n place we can also deserialize as a json object.

They key will be a json that loos like this: {"id":"119"} 


Create the KafkaConnect object

Code Block
languagetext
titleKafkaConnect
apiVersion: kafka.strimzi.io/v1beta1
kind: KafkaUser
metadata:
  name: connect
  namespace: kafka
  labels:
    strimzi.io/cluster: my-cluster
spec:
  authentication:
    type: tls
---
apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnect
metadata:
  name: my-connect-cluster
  namespace: kafka
  annotations:
  # use-connector-resources configures this KafkaConnect
  # to use KafkaConnector resources to avoid
  # needing to call the Connect REST API directly
    strimzi.io/use-connector-resources: "true"
spec:   
  image: ktimoney/strimzi-minio-connect
  replicas: 1
  bootstrapServers: my-cluster-kafka-bootstrap:9093
  tls:
    trustedCertificates:
      - secretName: my-cluster-cluster-ca-cert
        certificate: ca.crt
      -   "values"secretName: [my-cluster-clients-ca-cert
        certificate: ca.crt
  authentication:
    type: tls
    certificateAndKey:
[      secretName: connect
          certificate: user.crt
      key: user.key
  "2023-01-23T13:03:32.1246436Z",config:
    group.id: connect-cluster      
    offset.storage.topic: connect-cluster-offsets
    config.storage.topic: connect-cluster-configs
     "IE-region",status.storage.topic: connect-cluster-status
    # -1 means it will use the default replication factor configured in the broker
          "localhost",
   config.storage.replication.factor: -1
    offset.storage.replication.factor: -1
    status.storage.replication.factor: -1


We are connecting to the 9093 tls port so we include required certificates in our configuration.

The image tag references the image we built earlier : ktimoney/strimzi-minio-connect


Create the Sink connector

Code Block
languagetext
titleKafkaConnector
apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnector
metadata:
  name: my-sink-connector
  namespace: kafka
  labels:
   "81%",
   strimzi.io/cluster: my-connect-cluster
spec:   
  class: org.apache.camel.kafkaconnector.miniosink.CamelMiniosinkSinkConnector   
  tasksMax: 1   
  config:
    topics: my-topic
"19%"    key.converter: org.apache.kafka.connect.json.JsonConverter
    value.converter: org.apache.kafka.connect.storage.StringConverter
    key.converter.schemas.enable: false
    value.converter.schemas.enable: false     ]    
    camel.beans.aggregate: "#class:com.custom.aggregate.minio.CustomStringAggregator"
    camel.aggregation.size: 1
    ]
camel.aggregation.timeout: 20000
    camel.aggregation.disable: false     
    camel.kamelet.minio-sink.bucketName: camel
}    camel.kamelet.minio-sink.accessKey: ybK7RleFUkdDeYBf
    camel.kamelet.minio-sink.secretKey: X0Y4zK84bwdefRTljrnPzOb1l0A6OQj2
 ]   camel.kamelet.minio-sink.endpoint: http://minio.default:9000
    }
    ]
}

Minio Sink Connector (Apache Camel)

Prepare the connector image

Download the minio sink connector: wget https://repo.maven.apache.org/maven2/org/apache/camel/kafkaconnector/camel-file-kafka-connector/3.20.0/camel-file-kafka-connector-3.20.0-package.tar.gz

We need to create some custom classes:

CamelMinioConverters.java - this will allow us to deserialize to json and convert the hashmap to an inputstream

Code Block
languagejava
titleCamelMinioConverters
package com.custom.convert.minio;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.util.Map;
import org.apache.camel.Converter;

@Converter(generateLoader = true)
public final class CamelMinioConverters {

    private CamelMinioConverters() {
    }

    @SuppressWarnings("deprecation")
    @Converter
    public static InputStream fromMapToInputStream(Map<String, Object> map) {

      String json = "{}";
      try {
        json = new ObjectMapper().writeValueAsString(map);
      } catch (JsonProcessingException e) {
        e.printStackTrace();
      }
     return new ByteArrayInputStream(json.getBytes());
    }

}

StringAggregator.java - this will allow us to aggregate the messages and set the file name

Code Block
languagejava
titleStringAggregator
package com.custom.aggregate.minio;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import org.apache.camel.AggregationStrategy;
import org.apache.camel.Exchange;
import org.apache.camel.Message;

public class CustomStringAggregator implements AggregationStrategy {

    //@Override
    public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
      Message newIn = newExchange.getIn();
      Map<String, String> keyMap = (HashMap) newIn.getHeaders().get("camel.kafka.connector.record.key");
      String key = keyMap.get("id");
      SimpleDateFormat sdf = new SimpleDateFormat("ddMMyy-hhmmss-SSS");              
      String fileName = "ExchangeKafka-" + key + "-" + sdf.format( new Date() ) + ".json";
      newIn.setHeader("file", fileName);               

     // lets append the old body to the new body
        if (oldExchange == null) {
            return newExchange;
        }

        String body = oldExchange.getIn().getBody(String.class);
        if (body != null) {
            String newBody = newIn.getBody(String.class);camel.kamelet.minio-sink.autoCreateBucket: true


The KafkaConnector is configured to use the "org.apache.camel.kafkaconnector.miniosink.CamelMiniosinkSinkConnector class.

The value converter is set to "org.apache.kafka.connect.storage.StringConverter".

The minio connection details are specified in camel.kamelet.minio-sink parameters.

The aggregation size is set to 1 so it won't aggregate any of the files

This timeout is also specified so it will only aggregate records arriving within this time out value (20 seconds).

These values can be adjusted depending on your requirements.

The main purpose of the aggregator in this example is for setting the file name, this is done by setting a header with a key of "file".

The yaml for the minio pod is available here: minio.yaml


When the connector is running it copies the kafka records into minio as files:

Image Added


Here's a screen shot where we use the aggregator to set the file name:

Image Added



File Sink Connector (Apache Camel)

Prepare the connector image

Download the file connector: wget https://repo.maven.apache.org/maven2/org/apache/camel/kafkaconnector/camel-file-kafka-connector/3.20.0/camel-file-kafka-connector-3.20.0-package.tar.gz

Create a docker file for this connector


Code Block
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titleDocker
FROM quay.io/strimzi/kafka:0.32.0-kafka-3.3.1
USER root:root
RUN mkdir -p /opt/kafka/plugins/camel
COPY ./camel-file-kafka-connector-3.20.0-package.tar.gz /opt/kafka/plugins/camel/
RUN tar -xvzf /opt/kafka/plugins/camel/camel-file-kafka-connector-3.20.0-package.tar.gz --directory /opt/kafka/plugins/camel
RUN rm /opt/kafka/plugins/camel/camel-file-kafka-connector-3.20.0-package.tar.gz
RUN rm -rf /opt/kafka/plugins/camel/docs
USER 1001

Build the image and copy it to your docker repository

docker build -f Dockerfile . t ktimoney/strimzi_file_connector



Prepare the message producer

In this example we are going to deserialize the value to a string.

The value will take the following format:

Code Block
languagejs
titleSchema & Payload
{
"camelInfluxDB.MeasurementName":"disk_space"
"time":"2023-01-23T13:03:31Z"
"host":"localhost"
"region":"IE-region"
"used":"19%"
"free":"81%"
}



Due to some limitation with Strimzi KafkaConnect we will need to use a mutating webhook to attach a persistent volume to our connector pod.

The go code for this is available here:  kafka-webhook.go

We need to create a docker image for this program

Code Block
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titleWebhook docker
FROM golang:latest
RUN mkdir /app
COPY ./kafka-webhook /app
RUN chmod +x /app/kafka-webhook
WORKDIR /app
ENTRYPOINT ["/app/kafka-webhook"]

docker build -f Dockerfile . -t ktimoney/kafka-webhook

Mutating webhooks require https so we also need to create some certificates.

Make sure cfssl is installed on you system, then run the following commands.

cfssl gencert -initca ./ca-csr.json | cfssljson -bare ca

cfssl gencert \
  -ca=ca.pem \
  -ca-key=ca-key.pem \
  -config=ca-config.json \
  -hostname="kafka-webhook,kafka-webhook.kafka.svc.cluster.local,kafka-webhook.kafka.svc,localhost,127.0.0.1" \
  -profile=default \
  ca-csr.json | cfssljson -bare webhook-cert


Run the following commands to create the values you need to use in the yaml file:

TLS_CRT=$(cat webhook-cert.pem | base64 | tr -d '\n')

TLS_KEY=$(cat webhook-cert-key.pem | base64 | tr -d '\n')

CA_BUNDLE="$(openssl base64 -A <"ca.pem")"

Replace the values in : kafka-webhook.yaml

Note: You can also configure the hostPath and the containerPath as part of the deployment:

Code Block
languageyml
titleContainer command args
      containers:
      - name: kafka-webhook
        image: ktimoney/kafka-webhook
        imagePullPolicy: IfNotPresent
        command: ["/app/kafka-webhook"]
        args: [
  if (newBody != null) {          "-port", "8443",
     body += System.lineSeparator() + newBody;       "-tlsCertFile", "/certs/tls.crt",
    }              newIn.setBody(body);"-tlsKeyFile", "/certs/tls.key",
        }         return newExchange;"-hostPath", "/var/strimzi/files",
     } }

We can then create a custom jar for our code and copy it into the docker container.

Create a docker file for this connector

Code Block
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titleDocker
FROM quay.io/strimzi/kafka:0.32.0-kafka-3.3.1
USER root:root
RUN mkdir -p /opt/kafka/plugins/camel
COPY ./camel-minio-sink-kafka-connector-3.20.0-package.tar.gz /opt/kafka/plugins/camel/
RUN tar -xvzf /opt/kafka/plugins/camel/camel-minio-sink-kafka-connector-3.20.0-package.tar.gz --directory /opt/kafka/plugins/camel
COPY ./custom-converter-1.0.0.jar /opt/kafka/plugins/camel/camel-minio-sink-kafka-connector/
RUN rm /opt/kafka/plugins/camel/camel-minio-sink-kafka-connector-3.20.0-package.tar.gzRUN rm -rf /opt/kafka/plugins/camel/docs
USER 1001

Build the image and copy it to your docker repository

docker build -f Dockerfile . t ktimoney/strimzi_minio_connector

Prepare the message producer

In this example we are going to deserialize the value to a string. (Same producer as the influxdb example)

They will take the following format:

Code Block
languagejs
titleSchema & Payload
{
"camelInfluxDB.MeasurementName":"disk_space"
"time":"2023-01-23T13:03:31Z"
"host":"localhost"
"region":"IE-region"
"used":"19%"
"free":"81%"
}

With the type converter n place we can also deserialize as a json object.

They key will be a json that loos like this: {"id":"119"} 

Create the KafkaConnect object

Code Block
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titleKafkaConnect
apiVersion: kafka.strimzi.io/v1beta1
kind: KafkaUser
metadata:
  name: connect
  namespace: kafka
  labels:
    strimzi.io/cluster: my-cluster
spec:
  authentication:
    type: tls
---
apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnect
metadata:
  name: my-connect-cluster
  namespace: kafka
  annotations:
  # use-connector-resources configures this KafkaConnect
  # to use KafkaConnector resources to avoid
  # needing to call the Connect REST API directly
    strimzi.io/use-connector-resources: "true"
spec:   
  image: ktimoney/strimzi-minio-connect
  replicas: 1
  bootstrapServers: my-cluster-kafka-bootstrap:9093
  tls:
    trustedCertificates:
      - secretName: my-cluster-cluster-ca-cert
        certificate: ca.crt
      - secretName: my-cluster-clients-ca-cert
        certificate: ca.crt
  authentication:
    type: tls
    certificateAndKey:
      secretName: connect
      certificate: user.crt
      key: user.key
  config:
    group.id: connect-cluster      
    offset.storage.topic: connect-cluster-offsets
    config.storage.topic: connect-cluster-configs
    status.storage.topic: connect-cluster-status
    # -1 means it will use the default replication factor configured in the broker
    config.storage.replication.factor: -1
    offset.storage.replication.factor: -1
    status.storage.replication.factor: -1

We are connecting to the 9093 tls port so we include required certificates in our configuration.

...

          "-containerPath", "/opt/kafka/data"
              ]



Run: kubectl create -f kafka webhook.yaml to start the pod.

Note: You can delete the webhook once the connector pod starts.


Create the KafkaConnect object

Code Block
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titleKafkaConnect
apiVersion: kafka.strimzi.io/v1beta1
kind: KafkaUser
metadata:
  name: connect
  namespace: kafka
  labels:
    strimzi.io/cluster: my-cluster
spec:
  authentication:
    type: tls
---
apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnect
metadata:
  name: my-connect-cluster
  namespace: kafka  
  labels:
    webhook: "true"
  annotations:
  # use-connector-resources configures this KafkaConnect
  # to use KafkaConnector resources to avoid
  # needing to call the Connect REST API directly
    strimzi.io/use-connector-resources: "true"
spec:   
  image: ktimoney/strimzi-file-connect
  replicas: 1
  bootstrapServers: my-cluster-kafka-bootstrap:9093
  tls:
    trustedCertificates:
      - secretName: my-cluster-cluster-ca-cert
        certificate: ca.crt
      - secretName: my-cluster-clients-ca-cert
        certificate: ca.crt
  authentication:
    type: tls
    certificateAndKey:
      secretName: connect
      certificate: user.crt
      key: user.key
  config:
    group.id: connect-cluster
    offset.storage.topic: connect-cluster-offsets
    config.storage.topic: connect-cluster-configs
    status.storage.topic: connect-cluster-status
    config.storage.replication.factor: 1
    offset.storage.replication.factor: 1
    status.storage.replication.factor: 1


We are connecting to the 9093 tls port so we include required certificates in our configuration.

The image tag references the image we built earlier : ktimoney/strimzi-file-connect

In the metadata section of KafkaConnect I have added a new label webhook: "true", this will be picked up by the MutatingWebhookConfiguration:


Code Block
languageyml
titleMutatingWebhookConfiguration
apiVersion: admissionregistration.k8s.io/v1
kind: MutatingWebhookConfiguration
metadata:
  name: kafka-webhook-config
  namespace: kafka
  annotations:
    cert-manager.io/inject-ca-from-secret: kafka/kafka-webhook-cert
webhooks:
  - name: kafka-webhook.kafka.svc.cluster.local
    admissionReviewVersions:
      - "v1"
    sideEffects: "None"
    timeoutSeconds: 30
    objectSelector:
      matchLabels:
        webhook: "true"

matchLabels: webhook: "true"


Create the Sink connector

Code Block
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titleKafkaConnector
apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnector
metadata:
  name: my-sink-connector
  namespace: kafka
  labels:
    strimzi.io/cluster: my-connect-cluster
spec:   
  class: org.apache.camel.kafkaconnector.miniosinkfile.CamelMiniosinkSinkConnector  CamelFileSinkConnector
   tasksMax tasksMax: 1  
   config:
    topics: my-topic 
    keyvalue.converter: org.apache.kafka.connect.jsonstorage.JsonConverterStringConverter
     valuekey.converter: org.apache.kafka.connect.storagejson.StringConverterJsonConverter
    key.converter.schemas.enable: false
    value.converter.schemas.enable: false        
     camel.beans.aggregate: "#class:com.custom.aggregate.minio.CustomStringAggregator"
    camel.aggregation.size: 1
    camel.aggregation.timeout: 20000
    camel.aggregation.disable: false     
    camel.kamelet.minio-sink.bucketName: camelsink.endpoint.fileName: mydata-${date:now:ddMMyy-hhmmss-SSS}.txt
    camel.kameletsink.minio-sinkpath.accessKeydirectoryName: ybK7RleFUkdDeYBf/opt/kafka/data
    camel.kameletsink.minio-sinkendpoint.secretKeyfileExist: X0Y4zK84bwdefRTljrnPzOb1l0A6OQj2Append
    camel.kamelet.minio-sink.endpoint.autoCreate: http://minio.default:9000true
    camel.kamelet.minio-sink.autoCreateBucketaggregation.disable: true


The KafkaConnector is configured to use the "org.apache.camel.kafkaconnector.miniosink.CamelMiniosinkSinkConnector class.The value converter are set to "org.apache.kafka.connect.storage.StringConverter".

The minio connection details are specified in camel.kamelet.minio-sink parameters.

The aggregation size is set to 1 so it won't aggregate any of the files

This timeout is also specified so it will only aggregate records arriving within this time out value (20 seconds).

These values can be adjusted depending on your requirements.

The main purpose of the aggregator in this example is for setting the file name, this is done by setting a header with a key of "file".

The yaml for the minio pod is available here: minio.yaml

When the connector is running it copies the kafka records into minio as files:

Image Removed

Here's a screen shot where we use the aggregator to set the file name:

Image Removed.apache.camel.kafkaconnector.file.CamelFileSinkConnector" class.

The value converter is set to "org.apache.kafka.connect.storage.StringConverter".

The connector filename is set using the expression:  mydata-${date:now:ddMMyy-hhmmss-SSS}.txt

When the connector starts your kafka records will be copied to the persistent volume as files:

Image Added


Links

Kafka Connect And Schemas

...

How to Write a Connector for Kafka Connect – Deep Dive into Configuration Handling

Apache Camel

Camel Kafka Connector Examples

...

Camel Basic Configuration

Camel Components Source Code

Camel Kafka Connector Source Code

Using secrets in Kafka Connect configuration

Kafka Connect Transformations