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This guide provides instructions for migrating to a new version of ibc-go. Note: ibc-go supports golang semantic versioning and therefore all imports must be updated on major version releases. In addition, for this release, the 08-wasm module has been released as v10, and the callbacks middleware has been moved into the ibc-go module itself. Diff examples are shown after the list of overall changes:
  • To add support for IBC v2, Chains will need to wire up a new IBC v2 Transfer stack
  • Chains will need to wire up the new light client modules
  • Chains will need to update Keeper construction calls to comply with the new signatures
  • Chains will need to remove the route for the legacy proposal handler for 02-client from their app/app.go
  • Chains will need to remove the capability keeper and all related setup, including the scoped keepers from their app/app.go
  • Chains will need to remove ibc fee middleware (29-fee)
  • Chains will need, if using this module, to update their imports and usage of github.com/cosmos/ibc-go/modules/light-clients/08-wasm/ to github.com/cosmos/ibc-go/modules/light-clients/08-wasm/v10
  • Chains will need, if using this module, to update their imports and usage of github.com/cosmos/ibc-go/modules/apps/callbacks to github.com/cosmos/ibc-go/v10/modules/apps/callbacks
To add IBC v2 support, wire up a new transfer stack. Example below showing wired up with IBC Callbacks module: 
+ var ibcv2TransferStack ibcapi.IBCModule
+ ibcv2TransferStack = transferv2.NewIBCModule(app.TransferKeeper)
+ ibcv2TransferStack = ibccallbacksv2.NewIBCMiddleware(
+   transferv2.NewIBCModule(app.TransferKeeper),
+   app.IBCKeeper.ChannelKeeperV2,
+   wasmStackIBCHandler,
+   app.IBCKeeper.ChannelKeeperV2,
+   maxCallbackGas,
+ )
Wire up each light client as a separate module and add them to the client keeper router. Example below for 07-tendermint and 08-wasm: 
+ / Light client modules
+ clientKeeper := app.IBCKeeper.ClientKeeper
+ storeProvider := app.IBCKeeper.ClientKeeper.GetStoreProvider()
+
+ tmLightClientModule := ibctm.NewLightClientModule(appCodec, storeProvider)
+ clientKeeper.AddRoute(ibctm.ModuleName, &tmLightClientModule)
+
+ wasmLightClientModule := ibcwasm.NewLightClientModule(app.WasmClientKeeper, storeProvider)
+ clientKeeper.AddRoute(ibcwasmtypes.ModuleName, &wasmLightClientModule)
Remove ibc fee module name (if used) from module account permissions: 
  / app.go
  ...
  / module account permissions
  var maccPerms = map[string][]string{
    ...
-   ibcfeetypes.ModuleName:      nil,
    ...
  }
Remove CapabilityKeeper, IBCFeeKeeper and all capabilitykeeper.ScopedKeeper Scoped keepers from the App struct: 
  / ChainApp extended ABCI application
  type ChainApp struct {
    ...
-	CapabilityKeeper      *capabilitykeeper.Keeper
    ...
-   IBCFeeKeeper        ibcfeekeeper.Keeper
    ...
-   ScopedIBCKeeper           capabilitykeeper.ScopedKeeper
-	ScopedICAHostKeeper       capabilitykeeper.ScopedKeeper
-	ScopedICAControllerKeeper capabilitykeeper.ScopedKeeper
-	ScopedTransferKeeper      capabilitykeeper.ScopedKeeper
-	ScopedIBCFeeKeeper        capabilitykeeper.ScopedKeeper
    ...
  }
  ...
- app.ScopedIBCKeeper = scopedIBCKeeper
- app.ScopedTransferKeeper = scopedTransferKeeper
- app.ScopedWasmKeeper = scopedWasmKeeper
- app.ScopedICAHostKeeper = scopedICAHostKeeper
- app.ScopedICAControllerKeeper = scopedICAControllerKeeper
Remove capability and ibc fee middleware store keys from the NewKVStoreKeys call: 
...
  keys := storetypes.NewKVStoreKeys(
    ...
-   capabilitytypes.StoreKey,
-   ibcfeetypes.StoreKey,
    ...
  }
Remove the in-memory store keys previously used by the capability module: 
- memKeys := storetypes.NewMemoryStoreKeys(capabilitytypes.MemStoreKey)
...
- app.MountMemoryStores(memKeys)
Remove creation of the capability keeper: 
- / add capability keeper and ScopeToModule for ibc module
- 	app.CapabilityKeeper = capabilitykeeper.NewKeeper(
- 		appCodec,
- 		keys[capabilitytypes.StoreKey],
- 		memKeys[capabilitytypes.MemStoreKey],
- 	)

- 	scopedIBCKeeper := app.CapabilityKeeper.ScopeToModule(ibcexported.ModuleName)
- 	scopedICAHostKeeper := app.CapabilityKeeper.ScopeToModule(icahosttypes.SubModuleName)
- 	scopedICAControllerKeeper := app.CapabilityKeeper.ScopeToModule(icacontrollertypes.SubModuleName)
- 	scopedTransferKeeper := app.CapabilityKeeper.ScopeToModule(ibctransfertypes.ModuleName)
- 	scopedWasmKeeper := app.CapabilityKeeper.ScopeToModule(wasmtypes.ModuleName)
- 	app.CapabilityKeeper.Seal()
Remove the legacy route for the client keeper: 
...
  govRouter.AddRoute(govtypes.RouterKey, govv1beta1.ProposalHandler).
- AddRoute(paramproposal.RouterKey, params.NewParamChangeProposalHandler(app.ParamsKeeper)).
- AddRoute(ibcclienttypes.RouterKey, ibcclient.NewClientProposalHandler(app.IBCKeeper.ClientKeeper))
+ AddRoute(paramproposal.RouterKey, params.NewParamChangeProposalHandler(app.ParamsKeeper))
Update Core IBC Keeper constructor: 
  app.IBCKeeper = ibckeeper.NewKeeper(
	appCodec,
-	keys[ibcexported.StoreKey],
+	runtime.NewKVStoreService(keys[ibcexported.StoreKey]),
	app.GetSubspace(ibcexported.ModuleName),
-	app.StakingKeeper,
	app.UpgradeKeeper,
-	scopedIBCKeeper,
	authtypes.NewModuleAddress(govtypes.ModuleName).String(),
  )
Update IBC Transfer keeper constructor: 
  app.TransferKeeper = ibctransferkeeper.NewKeeper(
	appCodec,
-	keys[ibctransfertypes.StoreKey],
+	runtime.NewKVStoreService(keys[ibctransfertypes.StoreKey]),
	app.GetSubspace(ibctransfertypes.ModuleName),
	app.IBCKeeper.ChannelKeeper,
	app.IBCKeeper.ChannelKeeper,
-	app.IBCKeeper.PortKeeper,
+	app.MsgServiceRouter(),
	app.AccountKeeper,
	app.BankKeeper,
-	scopedTransferKeeper,
	authtypes.NewModuleAddress(govtypes.ModuleName).String(),
  )
Update ICA Host keeper constructor, notice the removal of the WithQueryRouter call in particular: 
  app.ICAHostKeeper = icahostkeeper.NewKeeper(
	appCodec,
-	keys[icahosttypes.StoreKey],
+	runtime.NewKVStoreService(keys[icahosttypes.StoreKey]),
	app.GetSubspace(icahosttypes.SubModuleName),
-	app.IBCFeeKeeper, / use ics29 fee as ics4Wrapper in middleware stack
	app.IBCKeeper.ChannelKeeper,
-	app.IBCKeeper.PortKeeper,
+	app.IBCKeeper.ChannelKeeper,
	app.AccountKeeper,
-	scopedICAHostKeeper,
	app.MsgServiceRouter(),
+	app.GRPCQueryRouter(),
	authtypes.NewModuleAddress(govtypes.ModuleName).String(),
  )
- app.ICAHostKeeper.WithQueryRouter(app.GRPCQueryRouter())
Remove IBC Fee Module keeper: 
- app.IBCFeeKeeper = ibcfeekeeper.NewKeeper(
-	appCodec, keys[ibcfeetypes.StoreKey],
-	app.IBCKeeper.ChannelKeeper, / may be replaced with IBC middleware
-	app.IBCKeeper.ChannelKeeper,
-	app.IBCKeeper.PortKeeper, app.AccountKeeper, app.BankKeeper,
- )
Update Transfer stack to remove the fee middleware. The example below shows the correct way to wire up a middleware stack with the IBC callbacks middleware: 
  / Create Transfer Stack
  var transferStack porttypes.IBCModule
  transferStack = transfer.NewIBCModule(app.TransferKeeper)
- transferStack = ibccallbacks.NewIBCMiddleware(transferStack, app.IBCFeeKeeper, wasmStackIBCHandler, maxCallbackGas)
- transferStack = ibcfee.NewIBCMiddleware(transferStack, app.IBCFeeKeeper)
+ / callbacks wraps the transfer stack as its base app, and uses PacketForwardKeeper as the ICS4Wrapper
+ / i.e. packet-forward-middleware is higher on the stack and sits between callbacks and the ibc channel keeper
+ / Since this is the lowest level middleware of the transfer stack, it should be the first entrypoint for transfer keeper's
+ / WriteAcknowledgement.
+ cbStack := ibccallbacks.NewIBCMiddleware(transferStack, app.PacketForwardKeeper, wasmStackIBCHandler, maxCallbackGas)
transferStack = packetforward.NewIBCMiddleware(
-	transferStack,
+	cbStack,
	app.PacketForwardKeeper,
	0,
	packetforwardkeeper.DefaultForwardTransferPacketTimeoutTimestamp,
  )
+ app.TransferKeeper.WithICS4Wrapper(cbStack)
Remove ibc fee middleware and any empty IBCModule (often dubbed noAuthzModule) from the ICA Controller stack creation: 
- var noAuthzModule porttypes.IBCModule
- icaControllerStack = icacontroller.NewIBCMiddleware(noAuthzModule, app.ICAControllerKeeper)
- icaControllerStack = ibcfee.NewIBCMiddleware(icaControllerStack, app.IBCFeeKeeper)
+ icaControllerStack = icacontroller.NewIBCMiddleware(app.ICAControllerKeeper)
Remove ibc fee middleware from ICA Host stack creation: 
  icaHostStack = icahost.NewIBCModule(app.ICAHostKeeper)
- icaHostStack = ibcfee.NewIBCMiddleware(icaHostStack, app.IBCFeeKeeper)
Update the module manager creation by removing the capability module, fee module and updating the tendermint app module constructor: 
  app.ModuleManager = module.NewManager(
    ...
-   capability.NewAppModule(appCodec, *app.CapabilityKeeper, false),
    ...
-   ibcfee.NewAppModule(app.IBCFeeKeeper),
    ...
-   ibctm.NewAppModule(),
+   ibctm.NewAppModule(tmLightClientModule),
    ...
  )
Remove the capability module and ibc fee middleware from SetOrderBeginBlockers, SetOrderEndBlockers, SetOrderInitGenesis and SetOrderExportGenesis: 
-   capabilitytypes.ModuleName,
-   ibcfeetypes.ModuleName,
If you use 08-wasm, you will need to update the go module that is used for QueryPlugins and AcceptListStargateQuerier. 
- wasmLightClientQuerier := ibcwasmtypes.QueryPlugins{
+ wasmLightClientQuerier := ibcwasmkeeper.QueryPlugins{
-	Stargate: ibcwasmtypes.AcceptListStargateQuerier([]string{
+	Stargate: ibcwasmkeeper.AcceptListStargateQuerier([]string{
		"/ibc.core.client.v1.Query/ClientState",
		"/ibc.core.client.v1.Query/ConsensusState",
		"/ibc.core.connection.v1.Query/Connection",
-	}),
+	}, app.GRPCQueryRouter()),
  }
If you use 08-wasm, you will need to use the wasm client keeper rather than the go module to initialize pinned codes: 
- if err := ibcwasmkeeper.InitializePinnedCodes(ctx); err != nil {
-	panic(fmt.Sprintf("ibcwasmkeeper failed initialize pinned codes %s", err))
+ if err := app.WasmClientKeeper.InitializePinnedCodes(ctx); err != nil {
+	panic(fmt.Sprintf("WasmClientKeeper failed initialize pinned codes %s", err))
+ }