[hw-6] add notifier service, kafka

notifier/internal/app/app.go

@@ -0,0 +1,83 @@
+package app
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"route256/notifier/internal/app/controller"
+	"route256/notifier/internal/domain/service"
+	"route256/notifier/internal/infra/config"
+	"route256/notifier/internal/infra/messaging/kafka"
+
+	"github.com/IBM/sarama"
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+)
+
+type App struct {
+	config *config.Config
+
+	controller *controller.Controller
+}
+
+func NewApp(configPath string) (*App, error) {
+	cfg, err := config.LoadConfig(configPath)
+	if err != nil {
+		return nil, fmt.Errorf("unable to load config: %w", err)
+	}
+
+	log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
+	zerolog.SetGlobalLevel(zerolog.InfoLevel)
+
+	if cfg.Service.LogLevel != "" {
+		level, logErr := zerolog.ParseLevel(cfg.Service.LogLevel)
+		if logErr != nil {
+			return nil, fmt.Errorf("unknown log level `%s` provided: %w", cfg.Service.LogLevel, logErr)
+		}
+
+		zerolog.SetGlobalLevel(level)
+	}
+
+	log.WithLevel(zerolog.GlobalLevel()).Msgf("using logging level=`%s`", zerolog.GlobalLevel().String())
+
+	consumer, err := setupSaramaConsumerGroup([]string{cfg.Kafka.Brokers}, cfg.Kafka.ConsumerGroupID)
+	if err != nil {
+		return nil, err
+	}
+
+	kafkaConsumer, err := kafka.NewStatusConsumer(cfg.Kafka.OrderTopic, consumer)
+	if err != nil {
+		return nil, fmt.Errorf("NewKafkaStatusConsumer: %w", err)
+	}
+
+	notifierService := service.NewNotifierService(kafkaConsumer)
+	controller := controller.NewController(notifierService)
+
+	return &App{
+		config:     cfg,
+		controller: controller,
+	}, err
+}
+
+func (a *App) Run(ctx context.Context) {
+	a.controller.Run(ctx)
+}
+
+func (a *App) Shutdown(ctx context.Context) error {
+	return a.controller.Stop(ctx)
+}
+
+func setupSaramaConsumerGroup(brokers []string, groupID string) (sarama.ConsumerGroup, error) {
+	cfg := sarama.NewConfig()
+	cfg.Consumer.Group.Rebalance.Strategy = sarama.NewBalanceStrategyRange()
+	cfg.Consumer.Offsets.Initial = sarama.OffsetNewest
+	cfg.Metadata.AllowAutoTopicCreation = false
+
+	group, err := sarama.NewConsumerGroup(brokers, groupID, cfg)
+	if err != nil {
+		return nil, fmt.Errorf("sarama.NewConsumerGroup: %w", err)
+	}
+
+	return group, nil
+}

notifier/internal/app/controller/controller.go

@@ -0,0 +1,74 @@
+package controller
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"sync"
+)
+
+type NotifierService interface {
+	RunFetchEvents(ctx context.Context) error
+}
+
+type Controller struct {
+	notifier NotifierService
+
+	wg     sync.WaitGroup
+	errCh  chan error
+	cancel context.CancelFunc
+}
+
+func NewController(notifierService NotifierService) *Controller {
+	return &Controller{
+		notifier: notifierService,
+		wg:       sync.WaitGroup{},
+		errCh:    make(chan error, 1),
+	}
+}
+
+// Run service asynchroniously.
+func (c *Controller) Run(ctx context.Context) {
+	ctx, cancel := context.WithCancel(ctx)
+	c.cancel = cancel
+
+	c.wg.Add(1)
+	go func() {
+		defer c.wg.Done()
+
+		if err := c.notifier.RunFetchEvents(ctx); err != nil && !errors.Is(err, context.Canceled) {
+			select {
+			case c.errCh <- fmt.Errorf("RunFetchEvents: %w", err):
+			default:
+			}
+		}
+	}()
+}
+
+// Gracefully stop service.
+func (c *Controller) Stop(ctx context.Context) error {
+	if c.cancel != nil {
+		c.cancel()
+	}
+
+	done := make(chan struct{})
+	go func() {
+		c.wg.Wait()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+
+	close(c.errCh)
+
+	select {
+	case err := <-c.errCh:
+		return err
+	default:
+		return nil
+	}
+}

notifier/internal/domain/service/service.go

@@ -0,0 +1,42 @@
+package service
+
+import (
+	"context"
+	"time"
+
+	"github.com/rs/zerolog/log"
+)
+
+type StatusConsumer interface {
+	FetchEvents(ctx context.Context) error
+}
+
+type NotifierService struct {
+	consumer StatusConsumer
+}
+
+func NewNotifierService(consumer StatusConsumer) *NotifierService {
+	return &NotifierService{
+		consumer: consumer,
+	}
+}
+
+func (s *NotifierService) RunFetchEvents(ctx context.Context) error {
+	backoff := 1 * time.Second
+
+	for {
+		if err := s.consumer.FetchEvents(ctx); err != nil {
+			if ctx.Err() != nil {
+				return ctx.Err()
+			}
+
+			log.Error().Err(err).Msgf("consume error (retrying in %d second(s))", backoff)
+		}
+
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case <-time.After(backoff):
+		}
+	}
+}

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
+}