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// -
// ========================LICENSE_START=================================
// Copyright (C) 2024: Deutsche Telecom
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ========================LICENSE_END===================================
// kafkacomm package provides a structured way to create and manage Kafka consumers,
// handle subscriptions, and read messages from Kafka topics
package kafkacomm
import (
"github.com/confluentinc/confluent-kafka-go/kafka"
"policy-opa-pdp/cfg"
"policy-opa-pdp/pkg/log"
"time"
)
// KafkaConsumerInterface defines the interface for a Kafka consumer.
type KafkaConsumerInterface interface {
Close() error
Unsubscribe() error
ReadMessage(timeout time.Duration) (*kafka.Message, error)
}
// KafkaConsumer is a wrapper around the Kafka consumer.
type KafkaConsumer struct {
Consumer KafkaConsumerInterface
}
// Close closes the KafkaConsumer
func (kc *KafkaConsumer) Close() {
kc.Consumer.Close()
}
// Unsubscribe unsubscribes the KafkaConsumer
func (kc *KafkaConsumer) Unsubscribe() error {
if err := kc.Consumer.Unsubscribe(); err != nil {
log.Warnf("Error Unsubscribing :%v", err)
return err
}
log.Debug("Unsubscribe From Topic")
return nil
}
// creates a new Kafka consumer and returns it
func NewKafkaConsumer() (*KafkaConsumer, error) {
brokers := cfg.BootstrapServer
groupid := cfg.GroupId
topic := cfg.Topic
useSASL := cfg.UseSASLForKAFKA
username := cfg.KAFKA_USERNAME
password := cfg.KAFKA_PASSWORD
// Add Kafka Connection Properties ....
configMap := &kafka.ConfigMap{
"bootstrap.servers": brokers,
"group.id": groupid,
"auto.offset.reset": "earliest",
}
//for STRIMZI-KAFKA in case sasl is enabled
if useSASL == "true" {
configMap.SetKey("sasl.mechanism", "SCRAM-SHA-512")
configMap.SetKey("sasl.username", username)
configMap.SetKey("sasl.password", password)
configMap.SetKey("security.protocol", "SASL_PLAINTEXT")
}
// create new Kafka Consumer
consumer, err := kafka.NewConsumer(configMap)
if err != nil {
log.Warnf("Error creating consumer: %v\n", err)
return nil, err
}
//subscribe to topic
err = consumer.SubscribeTopics([]string{topic}, nil)
if err != nil {
log.Warnf("Error subcribing to topic: %v\n", err)
return nil, err
}
log.Debugf("Topic Subscribed... : %v", topic)
return &KafkaConsumer{Consumer: consumer}, nil
}
// gets the Kafka messages on the subscribed topic
func ReadKafkaMessages(kc *KafkaConsumer) ([]byte, error) {
msg, err := kc.Consumer.ReadMessage(-1)
if err != nil {
log.Warnf("Error reading Kafka message: %v", err)
return nil, err
}
return msg.Value, nil
}
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