op-node: Add additional command to generate L2 configs (#3385)

* op-node: Add additional command to generate L2 configs

This command will be used in bedrock-regentool to replace the old hardhat scripts.

* fix linter

op-node/cmd/genesis/cmd.go

 package genesis
 
 import (
+	"context"
 	"encoding/json"
+	"errors"
 	"math/big"
 	"os"
+	"path/filepath"
+
+	"github.com/ethereum-optimism/optimism/op-bindings/hardhat"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/ethclient"
 
 	"github.com/ethereum-optimism/optimism/op-bindings/predeploys"
 	"github.com/ethereum-optimism/optimism/op-node/eth"
@@ -59,30 +68,7 @@ var Subcommands = cli.Commands{
 				return err
 			}
 
-			rollupConfig := &rollup.Config{
-				Genesis: rollup.Genesis{
-					L1: eth.BlockID{
-						Hash:   l1StartBlock.Hash(),
-						Number: 0,
-					},
-					L2: eth.BlockID{
-						Hash:   l2Genesis.ToBlock().Hash(),
-						Number: 0,
-					},
-					L2Time: uint64(config.L1GenesisBlockTimestamp),
-				},
-				BlockTime:              config.L2BlockTime,
-				MaxSequencerDrift:      config.MaxSequencerDrift,
-				SeqWindowSize:          config.SequencerWindowSize,
-				ChannelTimeout:         config.ChannelTimeout,
-				L1ChainID:              new(big.Int).SetUint64(config.L1ChainID),
-				L2ChainID:              new(big.Int).SetUint64(config.L2ChainID),
-				P2PSequencerAddress:    config.P2PSequencerAddress,
-				FeeRecipientAddress:    config.OptimismL2FeeRecipient,
-				BatchInboxAddress:      config.BatchInboxAddress,
-				BatchSenderAddress:     config.BatchSenderAddress,
-				DepositContractAddress: predeploys.DevOptimismPortalAddr,
-			}
+			rollupConfig := makeRollupConfig(config, l1StartBlock, l2Genesis, predeploys.DevOptimismPortalAddr)
 
 			if err := writeGenesisFile(ctx.String("outfile.l1"), l1Genesis); err != nil {
 				return err
@@ -93,6 +79,129 @@ var Subcommands = cli.Commands{
 			return writeGenesisFile(ctx.String("outfile.rollup"), rollupConfig)
 		},
 	},
+	{
+		Name:  "l2",
+		Usage: "Generates an L2 genesis file and rollup config suitable for a deployed network",
+		Flags: []cli.Flag{
+			cli.StringFlag{
+				Name:  "l1-rpc",
+				Usage: "L1 RPC URL",
+			},
+			cli.StringFlag{
+				Name:  "deploy-config",
+				Usage: "Path to hardhat deploy config file",
+			},
+			cli.StringFlag{
+				Name:  "deployment-dir",
+				Usage: "Path to deployment directory",
+			},
+			cli.StringFlag{
+				Name:  "outfile.l2",
+				Usage: "Path to L2 genesis output file",
+			},
+			cli.StringFlag{
+				Name:  "outfile.rollup",
+				Usage: "Path to rollup output file",
+			},
+		},
+		Action: func(ctx *cli.Context) error {
+			deployConfig := ctx.String("deploy-config")
+			config, err := genesis.NewDeployConfig(deployConfig)
+			if err != nil {
+				return err
+			}
+
+			if config.L1StartingBlockTag == nil {
+				return errors.New("must specify a starting block tag in genesis")
+			}
+
+			client, err := ethclient.Dial(ctx.String("l1-rpc"))
+			if err != nil {
+				return err
+			}
+
+			var l1StartBlock *types.Block
+			if config.L1StartingBlockTag.BlockHash != nil {
+				l1StartBlock, err = client.BlockByHash(context.Background(), *config.L1StartingBlockTag.BlockHash)
+			} else if config.L1StartingBlockTag.BlockNumber != nil {
+				l1StartBlock, err = client.BlockByNumber(context.Background(), big.NewInt(config.L1StartingBlockTag.BlockNumber.Int64()))
+			}
+			if err != nil {
+				return err
+			}
+
+			depPath, network := filepath.Split(ctx.String("deployment-dir"))
+			hh, err := hardhat.New(network, nil, []string{depPath})
+			if err != nil {
+				return err
+			}
+
+			proxyAdmin, err := hh.GetDeployment("ProxyAdmin")
+			if err != nil {
+				return err
+			}
+			l1SBP, err := hh.GetDeployment("L1StandardBridgeProxy")
+			if err != nil {
+				return err
+			}
+			l1XDMP, err := hh.GetDeployment("L1CrossDomainMessengerProxy")
+			if err != nil {
+				return err
+			}
+			portalProxy, err := hh.GetDeployment("OptimismPortalProxy")
+			if err != nil {
+				return err
+			}
+			l2Addrs := &genesis.L2Addresses{
+				ProxyAdmin:                  proxyAdmin.Address,
+				L1StandardBridgeProxy:       l1SBP.Address,
+				L1CrossDomainMessengerProxy: l1XDMP.Address,
+			}
+			l2Genesis, err := genesis.BuildL2DeveloperGenesis(config, l1StartBlock, l2Addrs)
+			if err != nil {
+				return err
+			}
+
+			rollupConfig := makeRollupConfig(config, l1StartBlock, l2Genesis, portalProxy.Address)
+
+			if err := writeGenesisFile(ctx.String("outfile.l2"), l2Genesis); err != nil {
+				return err
+			}
+			return writeGenesisFile(ctx.String("outfile.rollup"), rollupConfig)
+		},
+	},
+}
+
+func makeRollupConfig(
+	config *genesis.DeployConfig,
+	l1StartBlock *types.Block,
+	l2Genesis *core.Genesis,
+	portalAddr common.Address,
+) *rollup.Config {
+	return &rollup.Config{
+		Genesis: rollup.Genesis{
+			L1: eth.BlockID{
+				Hash:   l1StartBlock.Hash(),
+				Number: 0,
+			},
+			L2: eth.BlockID{
+				Hash:   l2Genesis.ToBlock().Hash(),
+				Number: 0,
+			},
+			L2Time: l1StartBlock.Time(),
+		},
+		BlockTime:              config.L2BlockTime,
+		MaxSequencerDrift:      config.MaxSequencerDrift,
+		SeqWindowSize:          config.SequencerWindowSize,
+		ChannelTimeout:         config.ChannelTimeout,
+		L1ChainID:              new(big.Int).SetUint64(config.L1ChainID),
+		L2ChainID:              new(big.Int).SetUint64(config.L2ChainID),
+		P2PSequencerAddress:    config.P2PSequencerAddress,
+		FeeRecipientAddress:    config.OptimismL2FeeRecipient,
+		BatchInboxAddress:      config.BatchInboxAddress,
+		BatchSenderAddress:     config.BatchSenderAddress,
+		DepositContractAddress: portalAddr,
+	}
 }
 
 func writeGenesisFile(outfile string, input interface{}) error {