Replace fmt.Println with a proper logger

Also add a comment on the starting height to be used for the indexer

cmd/server/main.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"flag"
 	"fmt"
-	"log"
 	"runtime"
 
 	goGrpc "google.golang.org/grpc"
@@ -45,13 +44,14 @@ func main() {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
-	runServer(config, store)
-	runIndexer(ctx, store)
+	logger := zerolog.New(zerolog.NewConsoleWriter()).With().Timestamp().Logger()
+	runServer(config, store, logger)
+	runIndexer(ctx, store, logger)
 
 	runtime.Goexit()
 }
 
-func runIndexer(ctx context.Context, store *storage.Store) {
+func runIndexer(ctx context.Context, store *storage.Store, logger zerolog.Logger) {
 	flowClient, err := grpc.NewBaseClient(
 		accessURL,
 		goGrpc.WithTransportCredentials(insecure.NewCredentials()),
@@ -60,12 +60,16 @@ func runIndexer(ctx context.Context, store *storage.Store) {
 		panic(err)
 	}
 
+	// TODO(m-Peter) The starting height from which the indexer should
+	// begins, should either be retrieved from storage (latest height + 1),
+	// or should be specified through a command-line flag (when starting
+	// from scratch).
 	latestBlockHeader, err := flowClient.GetLatestBlockHeader(ctx, true)
 	if err != nil {
 		panic(err)
 	}
-	fmt.Printf("Latest Block Height: %d\n", latestBlockHeader.Height)
-	fmt.Printf("Latest Block ID: %s\n", latestBlockHeader.ID)
+	logger.Info().Msgf("Latest Block Height: %d", latestBlockHeader.Height)
+	logger.Info().Msgf("Latest Block ID: %s", latestBlockHeader.ID)
 
 	data, errChan, initErr := flowClient.SubscribeEventsByBlockHeight(
 		ctx,
@@ -76,19 +80,19 @@ func runIndexer(ctx context.Context, store *storage.Store) {
 		grpc.WithHeartbeatInterval(1),
 	)
 	if initErr != nil {
-		log.Fatalf("could not subscribe to events: %v", initErr)
+		logger.Error().Msgf("could not subscribe to events: %v", initErr)
 	}
 
 	reconnect := func(height uint64) {
-		fmt.Printf("Reconnecting at block %d\n", height)
+		logger.Warn().Msgf("Reconnecting at block height: %d", height)
 
 		var err error
 		flowClient, err := grpc.NewBaseClient(
 			accessURL,
 			goGrpc.WithTransportCredentials(insecure.NewCredentials()),
 		)
 		if err != nil {
-			log.Fatalf("could not create flow client: %v", err)
+			logger.Error().Msgf("could not create flow client: %v", err)
 		}
 
 		data, errChan, initErr = flowClient.SubscribeEventsByBlockHeight(
@@ -100,7 +104,7 @@ func runIndexer(ctx context.Context, store *storage.Store) {
 			grpc.WithHeartbeatInterval(1),
 		)
 		if initErr != nil {
-			log.Fatalf("could not subscribe to events: %v", initErr)
+			logger.Error().Msgf("could not subscribe to events: %v", initErr)
 		}
 	}
 
@@ -117,23 +121,23 @@ func runIndexer(ctx context.Context, store *storage.Store) {
 				if ctx.Err() != nil {
 					return // graceful shutdown
 				}
-				fmt.Println("subscription closed - reconnecting")
+				logger.Error().Msg("subscription closed - reconnecting")
 				reconnect(lastHeight + 1)
 				continue
 			}
 
 			if response.Height != lastHeight+1 {
-				fmt.Printf("missed events response for block %d\n", lastHeight+1)
+				logger.Error().Msgf("missed events response for block %d", lastHeight+1)
 				reconnect(lastHeight)
 				continue
 			}
 
-			fmt.Printf("block %d %s:\n", response.Height, response.BlockID)
+			logger.Info().Msgf("block %d %s:", response.Height, response.BlockID)
 			if len(response.Events) > 0 {
 				store.StoreBlockHeight(ctx, response.Height)
 			}
 			for _, event := range response.Events {
-				fmt.Printf("  %s\n", event.Type)
+				logger.Info().Msgf("  %s", event.Type)
 			}
 
 			lastHeight = response.Height
@@ -148,22 +152,25 @@ func runIndexer(ctx context.Context, store *storage.Store) {
 				continue
 			}
 
-			fmt.Printf("~~~ ERROR: %s ~~~\n", err.Error())
+			logger.Error().Msgf("ERROR: %v", err)
 			reconnect(lastHeight + 1)
 			continue
 		}
 	}
 }
 
-func runServer(config *api.Config, store *storage.Store) {
-	srv := api.NewHTTPServer(zerolog.Logger{}, rpc.DefaultHTTPTimeouts)
+func runServer(config *api.Config, store *storage.Store, logger zerolog.Logger) {
+	srv := api.NewHTTPServer(logger, rpc.DefaultHTTPTimeouts)
 	supportedAPIs := api.SupportedAPIs(config, store)
+
 	srv.EnableRPC(supportedAPIs)
 	srv.EnableWS(supportedAPIs)
+
 	srv.SetListenAddr("localhost", 8545)
+
 	err := srv.Start()
 	if err != nil {
 		panic(err)
 	}
-	fmt.Println("Server Started: ", srv.ListenAddr())
+	logger.Info().Msgf("Server Started: %s", srv.ListenAddr())
 }