stream_block_headers.go

package main

import (
	"context"
	"log"
	"time"

	"github.com/onflow/flow/protobuf/go/flow/access"
	"github.com/onflow/flow/protobuf/go/flow/entities"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
)

const (
	accessURL = "access-008.mainnet25.nodes.onflow.org:9000"
)

func main() {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	conn, err := grpc.Dial(accessURL,
		grpc.WithTransportCredentials(insecure.NewCredentials()),
		grpc.WithDefaultCallOptions(grpc.MaxCallRecvMsgSize(1024*1024*20)),
	)
	if err != nil {
		log.Fatalf("could not connect to access api server: %v", err)
	}

	client := access.NewAccessAPIClient(conn)

	startHeader, err := client.GetLatestBlockHeader(ctx, &access.GetLatestBlockHeaderRequest{})
	if err != nil {
		log.Fatalf("could not get latest block header: %v", err)
	}

	stream, err := client.SubscribeBlockHeadersFromStartHeight(ctx, &access.SubscribeBlockHeadersFromStartHeightRequest{
		StartBlockHeight: startHeader.Block.Height,
		BlockStatus:      entities.BlockStatus_BLOCK_SEALED,
	})

	if err != nil {
		log.Fatalf("could not subscribe to block digests: %v", err)
	}

	for {
		header, err := stream.Recv()
		if err != nil {
			log.Fatalf("error receiving block digest: %v", err)
		}

		timestamp := header.Header.Timestamp.AsTime()
		log.Printf("%d %x %s", header.Header.Height, header.Header.Id, timestamp.Format(time.RFC3339Nano))
	}
}