[hw-6] add notifier service, kafka

notifier/internal/infra/config/config.go

@@ -0,0 +1,51 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+type Config struct {
+	Service struct {
+		LogLevel string `yaml:"log_level"`
+	} `yaml:"service"`
+
+	Kafka struct {
+		Host            string `yaml:"host"`
+		Port            string `yaml:"port"`
+		OrderTopic      string `yaml:"order_topic"`
+		ConsumerGroupID string `yaml:"consumer_group_id"`
+		Brokers         string `yaml:"brokers"`
+	} `yaml:"kafka"`
+}
+
+func LoadConfig(filename string) (*Config, error) {
+	workDir, err := os.Getwd()
+	if err != nil {
+		return nil, err
+	}
+	cfgRoot := filepath.Join(workDir, "configs")
+	absCfgRoot, _ := filepath.Abs(cfgRoot)
+
+	filePath := filepath.Join(absCfgRoot, filepath.Clean(filename))
+	if !strings.HasPrefix(filePath, absCfgRoot) {
+		return nil, fmt.Errorf("invalid path")
+	}
+
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	config := &Config{}
+	if err := yaml.NewDecoder(f).Decode(config); err != nil {
+		return nil, err
+	}
+
+	return config, nil
+}

notifier/internal/infra/messaging/kafka/consumer.go

@@ -0,0 +1,48 @@
+package kafka
+
+import (
+	"context"
+
+	"github.com/IBM/sarama"
+	"github.com/rs/zerolog/log"
+)
+
+type StatusConsumer struct {
+	group sarama.ConsumerGroup
+	topic string
+}
+
+func NewStatusConsumer(topic string, consumerGroup sarama.ConsumerGroup) (*StatusConsumer, error) {
+	return &StatusConsumer{
+		group: consumerGroup,
+		topic: topic,
+	}, nil
+}
+
+func (c *StatusConsumer) FetchEvents(ctx context.Context) error {
+	h := &statusHandler{}
+
+	return c.group.Consume(ctx, []string{c.topic}, h)
+}
+
+type statusHandler struct{}
+
+func (h *statusHandler) Setup(sess sarama.ConsumerGroupSession) error {
+	log.Info().Msgf("[notifier] assigned %v", sess.Claims())
+
+	return nil
+}
+
+func (h *statusHandler) Cleanup(_ sarama.ConsumerGroupSession) error {
+	return nil
+}
+
+func (h *statusHandler) ConsumeClaim(sess sarama.ConsumerGroupSession, claim sarama.ConsumerGroupClaim) error {
+	for msg := range claim.Messages() {
+		log.Info().Msgf("[order=%s] p=%d off=%d %s\n", string(msg.Key), msg.Partition, msg.Offset, string(msg.Value))
+
+		sess.MarkMessage(msg, "")
+	}
+
+	return nil
+}