Version: v7.8.x

Migrating from v4 to v5

This document is intended to highlight significant changes which may require more information than presented in the CHANGELOG. Any changes that must be done by a user of ibc-go should be documented here.

There are four sections based on the four potential user groups of this document:

Note: ibc-go supports golang semantic versioning and therefore all imports must be updated to bump the version number on major releases.

github.com/cosmos/ibc-go/v4 -> github.com/cosmos/ibc-go/v5

Chains

Ante decorator

The AnteDecorator type in core/ante has been renamed to RedundantRelayDecorator (and the corresponding constructor function to NewRedundantRelayDecorator). Therefore in the function that creates the instance of the sdk.AnteHandler type (e.g. NewAnteHandler) the change would be like this:

func NewAnteHandler(options HandlerOptions) (sdk.AnteHandler, error) {
   // parameter validation

   anteDecorators := []sdk.AnteDecorator{
      // other ante decorators
-     ibcante.NewAnteDecorator(opts.IBCkeeper),
+     ibcante.NewRedundantRelayDecorator(options.IBCKeeper),
   }

   return sdk.ChainAnteDecorators(anteDecorators...), nil
}

The AnteDecorator was actually renamed twice, but in this PR you can see the changes made for the final rename.

IBC Apps

Core

The key parameter of the NewKeeper function in modules/core/keeper is now of type storetypes.StoreKey (where storetypes is an import alias for "github.com/cosmos/cosmos-sdk/store/types"):

func NewKeeper(
   cdc codec.BinaryCodec,
-  key sdk.StoreKey,
+  key storetypes.StoreKey,
   paramSpace paramtypes.Subspace,
   stakingKeeper clienttypes.StakingKeeper,
   upgradeKeeper clienttypes.UpgradeKeeper,
   scopedKeeper capabilitykeeper.ScopedKeeper,
) *Keeper

The RegisterRESTRoutes function in modules/core has been removed.

ICS03 - Connection

The key parameter of the NewKeeper function in modules/core/03-connection/keeper is now of type storetypes.StoreKey (where storetypes is an import alias for "github.com/cosmos/cosmos-sdk/store/types"):

func NewKeeper(
   cdc codec.BinaryCodec,
-  key sdk.StoreKey,
+  key storetypes.StoreKey,
   paramSpace paramtypes.Subspace,
   ck types.ClientKeeper
) Keeper

ICS04 - Channel

The function NewPacketId in modules/core/04-channel/types has been renamed to NewPacketID:

-  func NewPacketId(
+  func NewPacketID(
  portID,
  channelID string,
  seq uint64
) PacketId

The key parameter of the NewKeeper function in modules/core/04-channel/keeper is now of type storetypes.StoreKey (where storetypes is an import alias for "github.com/cosmos/cosmos-sdk/store/types"):

func NewKeeper(
   cdc codec.BinaryCodec,
-  key sdk.StoreKey,
+  key storetypes.StoreKey,
   clientKeeper types.ClientKeeper,
   connectionKeeper types.ConnectionKeeper,
   portKeeper types.PortKeeper,
   scopedKeeper capabilitykeeper.ScopedKeeper,
) Keeper

ICS20 - Transfer

The key parameter of the NewKeeper function in modules/apps/transfer/keeper is now of type storetypes.StoreKey (where storetypes is an import alias for "github.com/cosmos/cosmos-sdk/store/types"):

func NewKeeper(
   cdc codec.BinaryCodec,
-  key sdk.StoreKey,
+  key storetypes.StoreKey,
   paramSpace paramtypes.Subspace,
   ics4Wrapper types.ICS4Wrapper,
   channelKeeper types.ChannelKeeper,
   portKeeper types.PortKeeper,
   authKeeper types.AccountKeeper,
   bankKeeper types.BankKeeper,
   scopedKeeper capabilitykeeper.ScopedKeeper,
) Keeper

The amount parameter of function GetTransferCoin in modules/apps/transfer/types is now of type math.Int ("cosmossdk.io/math"):

func GetTransferCoin(
   portID, channelID, baseDenom string,
-  amount sdk.Int
+  amount math.Int
) sdk.Coin

The RegisterRESTRoutes function in modules/apps/transfer has been removed.

ICS27 - Interchain Accounts

The key and msgRouter parameters of the NewKeeper functions in

modules/apps/27-interchain-accounts/controller/keeper
and modules/apps/27-interchain-accounts/host/keeper

have changed type. The key parameter is now of type storetypes.StoreKey (where storetypes is an import alias for "github.com/cosmos/cosmos-sdk/store/types"), and the msgRouter parameter is now of type *icatypes.MessageRouter (where icatypes is an import alias for "github.com/cosmos/ibc-go/v5/modules/apps/27-interchain-accounts/types"):

// NewKeeper creates a new interchain accounts controller Keeper instance
func NewKeeper(
   cdc codec.BinaryCodec,
-  key sdk.StoreKey,
+  key storetypes.StoreKey,
   paramSpace paramtypes.Subspace,
   ics4Wrapper icatypes.ICS4Wrapper,
   channelKeeper icatypes.ChannelKeeper,
   portKeeper icatypes.PortKeeper,
   scopedKeeper capabilitykeeper.ScopedKeeper,
-  msgRouter *baseapp.MsgServiceRouter,
+  msgRouter *icatypes.MessageRouter,
) Keeper

// NewKeeper creates a new interchain accounts host Keeper instance
func NewKeeper(
   cdc codec.BinaryCodec,
-  key sdk.StoreKey,
+  key storetypes.StoreKey,
   paramSpace paramtypes.Subspace,
   channelKeeper icatypes.ChannelKeeper,
   portKeeper icatypes.PortKeeper,
   accountKeeper icatypes.AccountKeeper,
   scopedKeeper capabilitykeeper.ScopedKeeper,
-  msgRouter *baseapp.MsgServiceRouter,
+  msgRouter *icatypes.MessageRouter,
) Keeper

The new MessageRouter interface is defined as:

type MessageRouter interface {
 	Handler(msg sdk.Msg) baseapp.MsgServiceHandler
}

The RegisterRESTRoutes function in modules/apps/27-interchain-accounts has been removed.

An additional parameter, ics4Wrapper has been added to the host submodule NewKeeper function in modules/apps/27-interchain-accounts/host/keeper. This allows the host submodule to correctly unwrap the channel version for channel reopening handshakes in the OnChanOpenTry callback.

func NewKeeper(
   cdc codec.BinaryCodec,
   key storetypes.StoreKey,
   paramSpace paramtypes.Subspace,
+  ics4Wrapper icatypes.ICS4Wrapper,
   channelKeeper icatypes.ChannelKeeper,
   portKeeper icatypes.PortKeeper,
   accountKeeper icatypes.AccountKeeper,
   scopedKeeper icatypes.ScopedKeeper,
   msgRouter icatypes.MessageRouter,
) Keeper

Cosmos SDK message handler responses in packet acknowledgement

The construction of the transaction response of a message execution on the host chain has changed. The Data field in the sdk.TxMsgData has been deprecated and since Cosmos SDK 0.46 the MsgResponses field contains the message handler responses packed into Anys.

For chains on Cosmos SDK 0.45 and below, the message response was constructed like this:

txMsgData := &sdk.TxMsgData{
   Data: make([]*sdk.MsgData, len(msgs)),
}

for i, msg := range msgs {
   // message validation

   msgResponse, err := k.executeMsg(cacheCtx, msg)
   // return if err != nil

   txMsgData.Data[i] = &sdk.MsgData{
      MsgType: sdk.MsgTypeURL(msg),
      Data:    msgResponse,
   }
}

// emit events

txResponse, err := proto.Marshal(txMsgData)
// return if err != nil

return txResponse, nil

And for chains on Cosmos SDK 0.46 and above, it is now done like this:

txMsgData := &sdk.TxMsgData{
   MsgResponses: make([]*codectypes.Any, len(msgs)),
}

for i, msg := range msgs {
   // message validation

   any, err := k.executeMsg(cacheCtx, msg)
   // return if err != nil

   txMsgData.MsgResponses[i] = any
}

// emit events

txResponse, err := proto.Marshal(txMsgData)
// return if err != nil

return txResponse, nil

When handling the acknowledgement in the OnAcknowledgementPacket callback of a custom ICA controller module, then depending on whether txMsgData.Data is empty or not, the logic to handle the message handler response will be different. Only controller chains on Cosmos SDK 0.46 or above will be able to write the logic needed to handle the response from a host chain on Cosmos SDK 0.46 or above.

var ack channeltypes.Acknowledgement
if err := channeltypes.SubModuleCdc.UnmarshalJSON(acknowledgement, &ack); err != nil {
   return err
}

var txMsgData sdk.TxMsgData
if err := proto.Unmarshal(ack.GetResult(), txMsgData); err != nil {
   return err
}

switch len(txMsgData.Data) {
case 0: // for SDK 0.46 and above
   for _, msgResponse := range txMsgData.MsgResponses {
      // unmarshall msgResponse and execute logic based on the response
   }
   return nil
default: // for SDK 0.45 and below
   for _, msgData := range txMsgData.Data {
      // unmarshall msgData and execute logic based on the response
   }
}

See ADR-03 for more information or the corresponding documentation about authentication modules.

ICS29 - Fee Middleware

The key parameter of the NewKeeper function in modules/apps/29-fee is now of type storetypes.StoreKey (where storetypes is an import alias for "github.com/cosmos/cosmos-sdk/store/types"):

func NewKeeper(
   cdc codec.BinaryCodec,
-  key sdk.StoreKey,
+  key storetypes.StoreKey,
   paramSpace paramtypes.Subspace,
   ics4Wrapper types.ICS4Wrapper,
   channelKeeper types.ChannelKeeper,
   portKeeper types.PortKeeper,
   authKeeper types.AccountKeeper,
   bankKeeper types.BankKeeper,
) Keeper

The RegisterRESTRoutes function in modules/apps/29-fee has been removed.

IBC testing package

The MockIBCApp type has been renamed to IBCApp (and the corresponding constructor function to NewIBCApp). This has resulted therefore in:

The IBCApp field of the *IBCModule in testing/mock to change its type as well to *IBCApp:

type IBCModule struct {
   appModule *AppModule
-  IBCApp    *MockIBCApp // base application of an IBC middleware stack
+  IBCApp    *IBCApp // base application of an IBC middleware stack
}

The app parameter to *NewIBCModule in testing/mock to change its type as well to *IBCApp:

func NewIBCModule(
   appModule *AppModule,
-  app *MockIBCApp
+  app *IBCApp
) IBCModule

The MockEmptyAcknowledgement type has been renamed to EmptyAcknowledgement (and the corresponding constructor function to NewEmptyAcknowledgement).

The TestingApp interface in testing has gone through some modifications:

The return type of the function GetStakingKeeper is not the concrete type stakingkeeper.Keeper anymore (where stakingkeeper is an import alias for "github.com/cosmos/cosmos-sdk/x/staking/keeper"), but it has been changed to the interface ibctestingtypes.StakingKeeper (where ibctestingtypes is an import alias for ""github.com/cosmos/ibc-go/v5/testing/types"). See this PR for more details. The StakingKeeper interface is defined as:

type StakingKeeper interface {
 	GetHistoricalInfo(ctx sdk.Context, height int64) (stakingtypes.HistoricalInfo, bool)
}

The return type of the function LastCommitID has changed to storetypes.CommitID (where storetypes is an import alias for "github.com/cosmos/cosmos-sdk/store/types").

See the following git diff for more details:

type TestingApp interface {
   abci.Application

   // ibc-go additions
   GetBaseApp() *baseapp.BaseApp
-  GetStakingKeeper() stakingkeeper.Keeper
+  GetStakingKeeper() ibctestingtypes.StakingKeeper
   GetIBCKeeper() *keeper.Keeper
   GetScopedIBCKeeper() capabilitykeeper.ScopedKeeper
   GetTxConfig() client.TxConfig

   // Implemented by SimApp
   AppCodec() codec.Codec

   // Implemented by BaseApp
-  LastCommitID() sdk.CommitID
+  LastCommitID() storetypes.CommitID
   LastBlockHeight() int64
}

The powerReduction parameter of the function SetupWithGenesisValSet in testing is now of type math.Int ("cosmossdk.io/math"):

func SetupWithGenesisValSet(
   t *testing.T,
   valSet *tmtypes.ValidatorSet,
   genAccs []authtypes.GenesisAccount,
   chainID string,
-  powerReduction sdk.Int,
+  powerReduction math.Int,
   balances ...banktypes.Balance
) TestingApp

The accAmt parameter of the functions

AddTestAddrsFromPubKeys ,
AddTestAddrs
and AddTestAddrsIncremental

in testing/simapp are now of type math.Int ("cosmossdk.io/math"):

func AddTestAddrsFromPubKeys(
   app *SimApp,
   ctx sdk.Context,
   pubKeys []cryptotypes.PubKey,
-  accAmt sdk.Int,
+  accAmt math.Int
)
func addTestAddrs(
   app *SimApp,
   ctx sdk.Context,
   accNum int,
-  accAmt sdk.Int,
+  accAmt math.Int,
   strategy GenerateAccountStrategy
) []sdk.AccAddress
func AddTestAddrsIncremental(
   app *SimApp,
   ctx sdk.Context,
   accNum int,
-  accAmt sdk.Int,
+  accAmt math.Int
) []sdk.AccAddress

The RegisterRESTRoutes function in testing/mock has been removed.

Relayers

No relevant changes were made in this release.

IBC Light Clients

ICS02 - Client

The key parameter of the NewKeeper function in modules/core/02-client/keeper is now of type storetypes.StoreKey (where storetypes is an import alias for "github.com/cosmos/cosmos-sdk/store/types"):

func NewKeeper(
   cdc codec.BinaryCodec,
-  key sdk.StoreKey,
+  key storetypes.StoreKey,
   paramSpace paramtypes.Subspace,
   sk types.StakingKeeper,
   uk types.UpgradeKeeper
) Keeper

Migrating from v4 to v5

Chains​

Ante decorator​

IBC Apps​

Core​

ICS03 - Connection​

ICS04 - Channel​

ICS20 - Transfer​

ICS27 - Interchain Accounts​

Cosmos SDK message handler responses in packet acknowledgement​

ICS29 - Fee Middleware​

IBC testing package​

Relayers​

IBC Light Clients​

ICS02 - Client​