Add InitiateFeeWithdrawal msg_server impl

Adds a message server implementation for the InitiateFeeWithdrawal
message to mimic the behavior of the OPStack's FeeVault contracts.

Users can permissionlessly triggers fee withdrawals on L2 if the
FeeCollector module account balance is above the predefined minimum
withdrawal amount. The fees are then able to be withdrawn to the
predefined target address on L1.

x/rollup/keeper/deposits.go

@@ -264,9 +264,9 @@ func (k *Keeper) mintETH(
 		types.EventTypeMintETH,
 		sdk.NewAttribute(types.AttributeKeyL1DepositTxType, types.L1UserDepositTxType),
 		sdk.NewAttribute(types.AttributeKeyMintCosmosAddress, mintAddr),
-		sdk.NewAttribute(types.AttributeKeyMint, hexutil.Encode(remainingCoins.BigInt().Bytes())),
+		sdk.NewAttribute(types.AttributeKeyMint, hexutil.EncodeBig(remainingCoins.BigInt())),
 		sdk.NewAttribute(types.AttributeKeyToCosmosAddress, recipientAddr),
-		sdk.NewAttribute(types.AttributeKeyValue, hexutil.Encode(transferAmount.BigInt().Bytes())),
+		sdk.NewAttribute(types.AttributeKeyValue, hexutil.EncodeBig(transferAmount.BigInt())),
 	)
 
 	return &mintEvent, nil
@@ -297,7 +297,7 @@ func (k *Keeper) mintERC20(
 		sdk.NewAttribute(types.AttributeKeyL1DepositTxType, types.L1UserDepositTxType),
 		sdk.NewAttribute(types.AttributeKeyToCosmosAddress, userAddr),
 		sdk.NewAttribute(types.AttributeKeyERC20Address, erc20addr),
-		sdk.NewAttribute(types.AttributeKeyValue, hexutil.Encode(amount.BigInt().Bytes())),
+		sdk.NewAttribute(types.AttributeKeyValue, hexutil.EncodeBig(amount.BigInt())),
 	)
 
 	return &mintEvent, nil

x/rollup/keeper/keeper.go

@@ -12,23 +12,26 @@ import (
 )
 
 type Keeper struct {
-	cdc          codec.BinaryCodec
-	storeService store.KVStoreService
-	rollupCfg    *rollup.Config
-	bankkeeper   types.BankKeeper
+	cdc           codec.BinaryCodec
+	storeService  store.KVStoreService
+	rollupCfg     *rollup.Config
+	bankkeeper    types.BankKeeper
+	accountkeeper types.AccountKeeper
 }
 
 func NewKeeper(
 	cdc codec.BinaryCodec,
 	storeService store.KVStoreService,
 	// dependencies
 	bankKeeper types.BankKeeper,
+	accountKeeper types.AccountKeeper,
 ) *Keeper {
 	return &Keeper{
-		cdc:          cdc,
-		storeService: storeService,
-		bankkeeper:   bankKeeper,
-		rollupCfg:    &rollup.Config{},
+		cdc:           cdc,
+		storeService:  storeService,
+		bankkeeper:    bankKeeper,
+		accountkeeper: accountKeeper,
+		rollupCfg:     &rollup.Config{},
 	}
 }
 

x/rollup/keeper/keeper_test.go

@@ -4,11 +4,13 @@ import (
 	"context"
 	"testing"
 
+	"cosmossdk.io/math"
 	storetypes "cosmossdk.io/store/types"
 	"github.com/cosmos/cosmos-sdk/runtime"
 	"github.com/cosmos/cosmos-sdk/testutil"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	moduletestutil "github.com/cosmos/cosmos-sdk/types/module/testutil"
+	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
 	"github.com/polymerdao/monomer/x/rollup/keeper"
 	rolluptestutil "github.com/polymerdao/monomer/x/rollup/testutil"
 	"github.com/polymerdao/monomer/x/rollup/types"
@@ -18,11 +20,12 @@ import (
 
 type KeeperTestSuite struct {
 	suite.Suite
-	ctx          context.Context
-	rollupKeeper *keeper.Keeper
-	bankKeeper   *rolluptestutil.MockBankKeeper
-	rollupStore  storetypes.KVStore
-	eventManger  sdk.EventManagerI
+	ctx           context.Context
+	rollupKeeper  *keeper.Keeper
+	bankKeeper    *rolluptestutil.MockBankKeeper
+	accountKeeper *rolluptestutil.MockAccountKeeper
+	rollupStore   storetypes.KVStore
+	eventManger   sdk.EventManagerI
 }
 
 func TestKeeperTestSuite(t *testing.T) {
@@ -35,23 +38,33 @@ func (s *KeeperTestSuite) SetupSubTest() {
 		s.T(),
 		storeKey,
 		storetypes.NewTransientStoreKey("transient_test")).Ctx
+	s.accountKeeper = rolluptestutil.NewMockAccountKeeper(gomock.NewController(s.T()))
 	s.bankKeeper = rolluptestutil.NewMockBankKeeper(gomock.NewController(s.T()))
 	s.rollupKeeper = keeper.NewKeeper(
 		moduletestutil.MakeTestEncodingConfig().Codec,
 		runtime.NewKVStoreService(storeKey),
 		s.bankKeeper,
+		s.accountKeeper,
 	)
 	sdkCtx := sdk.UnwrapSDKContext(s.ctx)
 	s.rollupStore = sdkCtx.KVStore(storeKey)
 	s.eventManger = sdkCtx.EventManager()
 }
 
 func (s *KeeperTestSuite) mockBurnETH() {
-	s.bankKeeper.EXPECT().SendCoinsFromAccountToModule(gomock.Any(), gomock.Any(), types.ModuleName, gomock.Any()).Return(nil).AnyTimes()
-	s.bankKeeper.EXPECT().BurnCoins(gomock.Any(), types.ModuleName, gomock.Any()).Return(nil).AnyTimes()
+	s.bankKeeper.EXPECT().SendCoinsFromAccountToModule(s.ctx, gomock.Any(), types.ModuleName, gomock.Any()).Return(nil).AnyTimes()
+	s.bankKeeper.EXPECT().BurnCoins(s.ctx, types.ModuleName, gomock.Any()).Return(nil).AnyTimes()
 }
 
 func (s *KeeperTestSuite) mockMintETH() {
-	s.bankKeeper.EXPECT().MintCoins(gomock.Any(), types.ModuleName, gomock.Any()).Return(nil).AnyTimes()
-	s.bankKeeper.EXPECT().SendCoinsFromModuleToAccount(gomock.Any(), types.ModuleName, gomock.Any(), gomock.Any()).Return(nil).AnyTimes()
+	s.bankKeeper.EXPECT().MintCoins(s.ctx, types.ModuleName, gomock.Any()).Return(nil).AnyTimes()
+	s.bankKeeper.EXPECT().SendCoinsFromModuleToAccount(s.ctx, types.ModuleName, gomock.Any(), gomock.Any()).Return(nil).AnyTimes()
+}
+
+func (s *KeeperTestSuite) mockFeeCollector() {
+	mockFeeCollectorAddress := sdk.AccAddress("fee_collector")
+	s.accountKeeper.EXPECT().GetModuleAddress(authtypes.FeeCollectorName).Return(mockFeeCollectorAddress).AnyTimes()
+	s.bankKeeper.EXPECT().GetBalance(s.ctx, mockFeeCollectorAddress, types.WEI).Return(sdk.NewCoin(types.WEI, math.NewInt(100_000))).AnyTimes()
+	s.bankKeeper.EXPECT().SendCoinsFromModuleToModule(s.ctx, authtypes.FeeCollectorName, types.ModuleName, gomock.Any()).Return(nil).AnyTimes()
+	s.bankKeeper.EXPECT().BurnCoins(s.ctx, types.ModuleName, gomock.Any()).Return(nil).AnyTimes()
 }

x/rollup/keeper/msg_server.go

@@ -2,8 +2,11 @@ package keeper
 
 import (
 	"context"
+	"math/big"
 
+	"cosmossdk.io/math"
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/polymerdao/monomer/x/rollup/types"
 	"github.com/samber/lo"
@@ -62,7 +65,7 @@ func (k *Keeper) InitiateWithdrawal(
 		return nil, types.WrapError(types.ErrBurnETH, "failed to burn ETH for cosmosAddress: %v; err: %v", cosmAddr, err)
 	}
 
-	withdrawalValueHex := hexutil.Encode(msg.Value.BigInt().Bytes())
+	withdrawalValueHex := hexutil.EncodeBig(msg.Value.BigInt())
 	k.EmitEvents(ctx, sdk.Events{
 		sdk.NewEvent(
 			types.EventTypeWithdrawalInitiated,
@@ -83,3 +86,71 @@ func (k *Keeper) InitiateWithdrawal(
 
 	return &types.MsgInitiateWithdrawalResponse{}, nil
 }
+
+func (k *Keeper) InitiateFeeWithdrawal(
+	goCtx context.Context,
+	_ *types.MsgInitiateFeeWithdrawal,
+) (*types.MsgInitiateFeeWithdrawalResponse, error) {
+	ctx := sdk.UnwrapSDKContext(goCtx)
+
+	// TODO: make minWithdrawalAmount and l1recipientAddr configurable once a genesis state is added
+	const (
+		minWithdrawalAmount   = 100
+		l1recipientAddr       = "0x63d93aC6FA6B4021527e967ac3Eb29F2B3E52B96"
+		feeWithdrawalGasLimit = 400_000
+	)
+
+	feeCollectorAddr := k.accountkeeper.GetModuleAddress(authtypes.FeeCollectorName)
+	if feeCollectorAddr == nil {
+		ctx.Logger().Error("Failed to get fee collector address")
+		return nil, types.WrapError(types.ErrInitiateFeeWithdrawal, "failed to get fee collector address")
+	}
+
+	feeCollectorBalance := k.bankkeeper.GetBalance(ctx, feeCollectorAddr, types.WEI)
+	if feeCollectorBalance.Amount.LT(math.NewInt(minWithdrawalAmount)) {
+		ctx.Logger().Error("Fee collector balance is below the minimum withdrawal amount", "balance", feeCollectorBalance.String())
+		return nil, types.WrapError(
+			types.ErrInitiateFeeWithdrawal,
+			"fee collector balance is below the minimum withdrawal amount: %v", feeCollectorBalance.String(),
+		)
+	}
+
+	ctx.Logger().Debug("Withdrawing L2 fees", "amount", feeCollectorBalance.String(), "recipient", l1recipientAddr)
+
+	// Burn the withdrawn fees from the fee collector account on L2. To avoid needing to enable burn permissions for the
+	// FeeCollector module account, they will first be sent to the rollup module account before being burned.
+	fees := sdk.NewCoins(feeCollectorBalance)
+	if err := k.bankkeeper.SendCoinsFromModuleToModule(ctx, authtypes.FeeCollectorName, types.ModuleName, fees); err != nil {
+		ctx.Logger().Error("Failed to send withdrawn fees from fee collector account to rollup module", "err", err)
+		return nil, types.WrapError(
+			types.ErrInitiateFeeWithdrawal,
+			"failed to send withdrawn fees from fee collector account to rollup module: %v", err,
+		)
+	}
+	if err := k.bankkeeper.BurnCoins(ctx, types.ModuleName, sdk.NewCoins(feeCollectorBalance)); err != nil {
+		ctx.Logger().Error("Failed to burn withdrawn fees from rollup module", "err", err)
+		return nil, types.WrapError(types.ErrInitiateFeeWithdrawal, "failed to burn withdrawn fees from rollup module: %v", err)
+	}
+
+	withdrawalValueHex := hexutil.EncodeBig(feeCollectorBalance.Amount.BigInt())
+	feeCollectorAddrStr := feeCollectorAddr.String()
+	k.EmitEvents(ctx, sdk.Events{
+		sdk.NewEvent(
+			types.EventTypeWithdrawalInitiated,
+			sdk.NewAttribute(types.AttributeKeySender, feeCollectorAddrStr),
+			sdk.NewAttribute(types.AttributeKeyL1Target, l1recipientAddr),
+			sdk.NewAttribute(types.AttributeKeyValue, withdrawalValueHex),
+			sdk.NewAttribute(types.AttributeKeyGasLimit, hexutil.EncodeBig(big.NewInt(feeWithdrawalGasLimit))),
+			sdk.NewAttribute(types.AttributeKeyData, "0x"),
+			// The nonce attribute will be set by Monomer
+		),
+		sdk.NewEvent(
+			types.EventTypeBurnETH,
+			sdk.NewAttribute(types.AttributeKeyL2FeeWithdrawalTx, types.EventTypeWithdrawalInitiated),
+			sdk.NewAttribute(types.AttributeKeyFromCosmosAddress, feeCollectorAddrStr),
+			sdk.NewAttribute(types.AttributeKeyValue, withdrawalValueHex),
+		),
+	})
+
+	return &types.MsgInitiateFeeWithdrawalResponse{}, nil
+}

x/rollup/keeper/msg_server_test.go

@@ -4,6 +4,7 @@ import (
 	"cosmossdk.io/math"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
+	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
 	"github.com/ethereum-optimism/optimism/op-service/eth"
 	gethtypes "github.com/ethereum/go-ethereum/core/types"
 	"github.com/golang/mock/gomock"
@@ -87,14 +88,14 @@ func (s *KeeperTestSuite) TestApplyL1Txs() {
 		"bank keeper mint coins failure": {
 			txBytes: [][]byte{l1AttributesTxBz, depositTxBz},
 			setupMocks: func() {
-				s.bankKeeper.EXPECT().MintCoins(gomock.Any(), types.ModuleName, gomock.Any()).Return(sdkerrors.ErrUnauthorized)
+				s.bankKeeper.EXPECT().MintCoins(s.ctx, types.ModuleName, gomock.Any()).Return(sdkerrors.ErrUnauthorized)
 			},
 			shouldError: true,
 		},
 		"bank keeper send coins failure": {
 			txBytes: [][]byte{l1AttributesTxBz, depositTxBz},
 			setupMocks: func() {
-				s.bankKeeper.EXPECT().SendCoinsFromModuleToAccount(gomock.Any(), types.ModuleName, gomock.Any(), gomock.Any()).Return(sdkerrors.ErrUnknownRequest)
+				s.bankKeeper.EXPECT().SendCoinsFromModuleToAccount(s.ctx, types.ModuleName, gomock.Any(), gomock.Any()).Return(sdkerrors.ErrUnknownRequest)
 			},
 			shouldError: true,
 		},
@@ -161,14 +162,14 @@ func (s *KeeperTestSuite) TestInitiateWithdrawal() {
 		},
 		"bank keeper insufficient funds failure": {
 			setupMocks: func() {
-				s.bankKeeper.EXPECT().SendCoinsFromAccountToModule(gomock.Any(), gomock.Any(), types.ModuleName, gomock.Any()).Return(types.ErrBurnETH)
+				s.bankKeeper.EXPECT().SendCoinsFromAccountToModule(s.ctx, gomock.Any(), types.ModuleName, gomock.Any()).Return(types.ErrBurnETH)
 			},
 			sender:      sender,
 			shouldError: true,
 		},
 		"bank keeper burn coins failure": {
 			setupMocks: func() {
-				s.bankKeeper.EXPECT().BurnCoins(gomock.Any(), types.ModuleName, gomock.Any()).Return(sdkerrors.ErrUnknownRequest)
+				s.bankKeeper.EXPECT().BurnCoins(s.ctx, types.ModuleName, gomock.Any()).Return(sdkerrors.ErrUnknownRequest)
 			},
 			sender:      sender,
 			shouldError: true,
@@ -208,3 +209,69 @@ func (s *KeeperTestSuite) TestInitiateWithdrawal() {
 		})
 	}
 }
+
+func (s *KeeperTestSuite) TestInitiateFeeWithdrawal() {
+	tests := map[string]struct {
+		setupMocks  func()
+		shouldError bool
+	}{
+		"successful message": {
+			shouldError: false,
+		},
+		"fee collector address not found": {
+			setupMocks: func() {
+				s.accountKeeper.EXPECT().GetModuleAddress(authtypes.FeeCollectorName).Return(nil)
+			},
+			shouldError: true,
+		},
+		"fee collector balance below minimum withdrawal amount": {
+			setupMocks: func() {
+				s.bankKeeper.EXPECT().GetBalance(s.ctx, gomock.Any(), types.WEI).Return(sdk.NewCoin(types.WEI, math.NewInt(1)))
+			},
+			shouldError: true,
+		},
+		"bank keeper send coins failure": {
+			setupMocks: func() {
+				s.bankKeeper.EXPECT().SendCoinsFromModuleToModule(s.ctx, authtypes.FeeCollectorName, types.ModuleName, gomock.Any()).Return(sdkerrors.ErrUnknownRequest)
+			},
+			shouldError: true,
+		},
+		"bank keeper burn coins failure": {
+			setupMocks: func() {
+				s.bankKeeper.EXPECT().BurnCoins(s.ctx, types.ModuleName, gomock.Any()).Return(sdkerrors.ErrUnknownRequest)
+			},
+			shouldError: true,
+		},
+	}
+
+	for name, test := range tests {
+		s.Run(name, func() {
+			if test.setupMocks != nil {
+				test.setupMocks()
+			}
+			s.mockFeeCollector()
+
+			resp, err := s.rollupKeeper.InitiateFeeWithdrawal(s.ctx, &types.MsgInitiateFeeWithdrawal{
+				Sender: sdk.AccAddress("addr").String(),
+			})
+
+			if test.shouldError {
+				s.Require().Error(err)
+				s.Require().Nil(resp)
+			} else {
+				s.Require().NoError(err)
+				s.Require().NotNil(resp)
+
+				// Verify that the expected event types are emitted
+				expectedEventTypes := []string{
+					sdk.EventTypeMessage,
+					types.EventTypeWithdrawalInitiated,
+					types.EventTypeBurnETH,
+				}
+				for i, event := range s.eventManger.Events() {
+					s.Require().Equal(expectedEventTypes[i], event.Type)
+				}
+			}
+		})
+	}
+}

x/rollup/module.go

@@ -12,6 +12,7 @@ import (
 	cdctypes "github.com/cosmos/cosmos-sdk/codec/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/types/module"
+	authkeeper "github.com/cosmos/cosmos-sdk/x/auth/keeper"
 	bankkeeper "github.com/cosmos/cosmos-sdk/x/bank/keeper"
 	protov1 "github.com/golang/protobuf/proto" //nolint:staticcheck
 	"github.com/gorilla/mux"
@@ -27,9 +28,10 @@ import (
 type ModuleInputs struct {
 	depinject.In
 
-	Codec        codec.Codec
-	StoreService store.KVStoreService
-	BankKeeper   bankkeeper.Keeper
+	Codec         codec.Codec
+	StoreService  store.KVStoreService
+	BankKeeper    bankkeeper.Keeper
+	AccountKeeper authkeeper.AccountKeeper
 }
 
 type ModuleOutputs struct {
@@ -53,8 +55,8 @@ func ProvideCustomGetSigner() signing.CustomGetSigner {
 	}
 }
 
-func ProvideModule(in ModuleInputs) ModuleOutputs {
-	k := keeper.NewKeeper(in.Codec, in.StoreService, in.BankKeeper)
+func ProvideModule(in ModuleInputs) ModuleOutputs { //nolint:gocritic // hugeParam
+	k := keeper.NewKeeper(in.Codec, in.StoreService, in.BankKeeper, in.AccountKeeper)
 	return ModuleOutputs{
 		Keeper: k,
 		Module: NewAppModule(in.Codec, k),