19createRawTransaction.go

package main

import (
	"bytes"
	"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 main() {
	client, err := ethclient.Dial("https://ropsten.infura.io/v3/28d5693e8bee4b58a61f0c627d62331e")
	if err != nil {
		log.Fatal(err)
	}

	privateKey, err := crypto.HexToECDSA(os.Getenv("PRIVATE_KEY"))
	if err != nil {
		log.Fatal(err)
	}

	publicKey := privateKey.Public()
	publicKeyECDSA, ok := publicKey.(*ecdsa.PublicKey)
	if !ok {
		log.Fatal("cannot assert type: publicKey is not of type *ecdsa.PublicKey")
	}

	fromAddress := crypto.PubkeyToAddress(*publicKeyECDSA)
	nonce, err := client.PendingNonceAt(context.Background(), fromAddress)
	if err != nil {
		log.Fatal(err)
	}

	value := big.NewInt(1000000000000000000) // in wei (1 eth)
	gasLimit := uint64(21000)                // in units
	gasPrice, err := client.SuggestGasPrice(context.Background())
	if err != nil {
		log.Fatal(err)
	}

	toAddress := common.HexToAddress("0x4592d8f8d7b001e72cb26a73e4fa1806a51ac79d")
	var data []byte
	tx := types.NewTx(&types.LegacyTx{
		Nonce:    nonce,
		To:       &toAddress,
		Value:    value,
		Gas:      gasLimit,
		GasPrice: gasPrice,
		Data:     data,
	})

	chainID, err := client.NetworkID(context.Background())
	if err != nil {
		log.Fatal(err)
	}

	signedTx, err := types.SignTx(tx, types.NewEIP155Signer(chainID), privateKey)
	if err != nil {
		log.Fatal(err)
	}

	ts := types.Transactions{signedTx}
	b := new(bytes.Buffer)
	ts.EncodeIndex(0, b)
	rawTxBytes := b.Bytes()
	rawTxHex := hex.EncodeToString(rawTxBytes)

	fmt.Printf(rawTxHex) // f86...772
}