main.go

package main

import (
	"context"
	"io"
	"os"

	"github.com/ethereum/go-ethereum/log"
	"github.com/flashbots/go-utils/blocksub"
	"golang.org/x/exp/slog"
)

var (
	httpURI  = os.Getenv("ETH_HTTP") // usually port 8545
	wsURI    = os.Getenv("ETH_WS")   // usually port 8546
	logJSON  = os.Getenv("LOG_JSON") == "1"
	logDebug = os.Getenv("DEBUG") == "1"
)

func logSetup() {
	logLevel := log.LevelInfo
	if logDebug {
		logLevel = log.LevelDebug
	}

	output := io.Writer(os.Stderr)
	var handler slog.Handler = log.NewTerminalHandlerWithLevel(output, logLevel, true)
	if logJSON {
		handler = log.JSONHandler(output)
	}

	log.SetDefault(log.NewLogger(handler))
}

func main() {
	logSetup()

	DemoSimpleSub(httpURI, wsURI)
	// DemoMultiSub(httpURI, wsURI)
}

func DemoSimpleSub(httpURI, wsURI string) {
	// Create and start a BlockSub instance
	blocksub := blocksub.NewBlockSub(context.Background(), httpURI, wsURI)
	blocksub.DebugOutput = true
	if err := blocksub.Start(); err != nil {
		log.Crit(err.Error())
	}

	// Create a subscription to new headers
	sub := blocksub.Subscribe(context.Background())
	for header := range sub.C {
		log.Info("new header", "number", header.Number.Uint64(), "hash", header.Hash().Hex())
	}
}