send_transaction.go

package main

import (
	"context"
	"crypto/ecdsa"
	"encoding/hex"
	"fmt"
	"log"
	"math/big"
	"os"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/ethclient"
)

func sendTransaction() {
	var (
		ctx         = context.Background()
		url         = "https://eth-goerli.g.alchemy.com/v2/" + os.Getenv("ALCHEMY_ID")
		client, err = ethclient.DialContext(ctx, url)
	)
	if err != nil {
		log.Fatal(err)
	}

	privateKey, err := crypto.HexToECDSA(os.Getenv("ACCOUNT_KEY"))
	publicKey := privateKey.Public()
	publicKeyECDSA, ok := publicKey.(*ecdsa.PublicKey)
	if !ok {
		log.Fatal("error casting public key to ECDSA")
	}

	fromAddress := crypto.PubkeyToAddress(*publicKeyECDSA)
	nonce, err := client.PendingNonceAt(context.Background(), fromAddress)
	if err != nil {
		log.Fatal(err)
	}
	value := big.NewInt(1) // 1 wei
	gasLimit := uint64(21000)
	gasFeeCap, err := client.SuggestGasPrice(context.Background())
	if err != nil {
		log.Fatal(err)
	}
	gasTipCap, err := client.SuggestGasTipCap(context.Background())
	if err != nil {
		log.Fatal(err)
	}
	toAddress := fromAddress // send eth to self
	var data []byte
	chainID, err := client.NetworkID(context.Background())
	if err != nil {
		log.Fatal(err)
	}

	tx := types.NewTx(&types.DynamicFeeTx{
		ChainID:   chainID,
		Nonce:     nonce,
		GasFeeCap: gasFeeCap,
		GasTipCap: gasTipCap,
		Gas:       gasLimit,
		To:        &toAddress,
		Value:     value,
		Data:      data,
	})

	signedTx, err := types.SignTx(tx, types.NewLondonSigner(chainID), privateKey)
	if err != nil {
		log.Fatal(err)
	}

	err = client.SendTransaction(context.Background(), signedTx)
	if err != nil {
		log.Fatal(err)
	}

	txHash := common.HexToHash(signedTx.Hash().Hex())
	tx, isPending, err := client.TransactionByHash(context.Background(), txHash)
	fmt.Println("transaction hash:", tx.Hash().Hex())
	fmt.Println("transaction value:", tx.Value().String())
	fmt.Println("transaction gas limit:", tx.Gas())
	fmt.Println("transaction fee cap per gas:", tx.GasFeeCap())
	fmt.Println("transaction tip cap per gas:", tx.GasTipCap())
	fmt.Println("transaction gas price:", tx.GasPrice())
	fmt.Println("transaction nonce:", tx.Nonce())
	fmt.Println("transaction data:", hex.EncodeToString(tx.Data()))
	fmt.Println("transaction to:", tx.To().Hex())
	fmt.Println("isPending:", isPending)
}