[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
+	}
+}