feat(server): add custom start handler

CHANGELOG.md

@@ -58,6 +58,9 @@ Every module contains its own CHANGELOG.md. Please refer to the module you are i
 
 ### Improvements
 
+* (server) [#19854](https://github.com/cosmos/cosmos-sdk/pull/19854) Add customizability to start command.
+    * Add `StartCmdOptions` in `server.AddCommands` instead of `servertypes.ModuleInitFlags`. To set custom flags set them in the `StartCmdOptions` struct on the `AddFlags` field.
+    * Add `StartCommandHandler` to `StartCmdOptions` to allow custom start command handlers. Users now have total control over how the app starts.
 * (types) [#19672](https://github.com/cosmos/cosmos-sdk/pull/19672) `PreBlock` now returns only an error for consistency with server/v2. The SDK has upgraded x/upgrade accordingly. `ResponsePreBlock` hence has been removed.
 * (server) [#19455](https://github.com/cosmos/cosmos-sdk/pull/19455) Allow calling back into the application struct in PostSetup.
 * (types) [#19512](https://github.com/cosmos/cosmos-sdk/pull/19512) The notion of basic manager does not exist anymore (and all related helpers).
@@ -102,6 +105,7 @@ Every module contains its own CHANGELOG.md. Please refer to the module you are i
 
 ### API Breaking Changes
 
+* (server) [#19854](https://github.com/cosmos/cosmos-sdk/pull/19854) Remove `servertypes.ModuleInitFlags` types and from `server.AddCommands` as `StartCmdOptions` already achieves the same goal.
 * (types) [#19792](https://github.com/cosmos/cosmos-sdk/pull/19792) In `MsgSimulatorFn` `sdk.Context` argument is replaced for an `address.Codec`. It also returns an error.
 * (types) [#19742](https://github.com/cosmos/cosmos-sdk/pull/19742) Removes the use of `Accounts.String`
     * `SimulationState` now has address and validator codecs as fields.

UPGRADING.md

@@ -31,6 +31,13 @@ clientCtx = clientCtx.
 
 Refer to SimApp `root_v2.go` and `root.go` for an example with an app v2 and a legacy app.
 
+Additionally, a simplification of the start command leads to the following change:
+
+```diff
+- server.AddCommands(rootCmd, newApp, func(startCmd *cobra.Command) {})
++ server.AddCommands(rootCmd, newApp, server.StartCmdOptions[servertypes.Application]{})
+```
+
 #### Server (`app.go`)
 
 ##### Module Manager

docs/build/building-apps/05-app-testnet.md

@@ -195,8 +195,8 @@ Before we can run the testnet we must plug everything together.
 in `root.go`, in the `initRootCmd` function we add:
 
 ```diff
-  server.AddCommands(rootCmd, simapp.DefaultNodeHome, newApp, createMerlinAppAndExport, addModuleInitFlags)
-	++ server.AddTestnetCreatorCommand(rootCmd, simapp.DefaultNodeHome, newTestnetApp, addModuleInitFlags)
+server.AddCommands(rootCmd, simapp.DefaultNodeHome, newApp, createMerlinAppAndExport)
++server.AddTestnetCreatorCommand(rootCmd, simapp.DefaultNodeHome, newTestnetApp)
 ```
 
 Next we will add a newTestnetApp helper function:

server/start.go

@@ -124,6 +124,8 @@ type StartCmdOptions[T types.Application] struct {
 	PostSetupStandalone func(app T, svrCtx *Context, clientCtx client.Context, ctx context.Context, g *errgroup.Group) error
 	// AddFlags add custom flags to start cmd
 	AddFlags func(cmd *cobra.Command)
+	// StartCommandHanlder can be used to customize the start command handler
+	StartCommandHandler func(svrCtx *Context, clientCtx client.Context, appCreator types.AppCreator[T], inProcessConsensus bool, opts StartCmdOptions[T]) error
 }
 
 // StartCmd runs the service passed in, either stand-alone or in-process with
@@ -139,6 +141,10 @@ func StartCmdWithOptions[T types.Application](appCreator types.AppCreator[T], op
 		opts.DBOpener = OpenDB
 	}
 
+	if opts.StartCommandHandler == nil {
+		opts.StartCommandHandler = start
+	}
+
 	cmd := &cobra.Command{
 		Use:   "start",
 		Short: "Run the full node",
@@ -187,7 +193,7 @@ is performed. Note, when enabled, gRPC will also be automatically enabled.
 			}
 
 			err = wrapCPUProfile(serverCtx, func() error {
-				return start(serverCtx, clientCtx, appCreator, withCMT, opts)
+				return opts.StartCommandHandler(serverCtx, clientCtx, appCreator, withCMT, opts)
 			})
 
 			serverCtx.Logger.Debug("received quit signal")
@@ -270,10 +276,7 @@ func startStandAlone[T types.Application](svrCtx *Context, svrCfg serverconfig.C
 		return err
 	}
 
-	cmtCfg := svrCtx.Config
-	home := cmtCfg.RootDir
-
-	err = startAPIServer(ctx, g, cmtCfg, svrCfg, clientCtx, svrCtx, app, home, grpcSrv, metrics)
+	err = startAPIServer(ctx, g, svrCfg, clientCtx, svrCtx, app, svrCtx.Config.RootDir, grpcSrv, metrics)
 	if err != nil {
 		return err
 	}
@@ -304,8 +307,6 @@ func startInProcess[T types.Application](svrCtx *Context, svrCfg serverconfig.Co
 	metrics *telemetry.Metrics, opts StartCmdOptions[T],
 ) error {
 	cmtCfg := svrCtx.Config
-	home := cmtCfg.RootDir
-
 	gRPCOnly := svrCtx.Viper.GetBool(flagGRPCOnly)
 
 	g, ctx := getCtx(svrCtx, true)
@@ -341,7 +342,7 @@ func startInProcess[T types.Application](svrCtx *Context, svrCfg serverconfig.Co
 		return err
 	}
 
-	err = startAPIServer(ctx, g, cmtCfg, svrCfg, clientCtx, svrCtx, app, home, grpcSrv, metrics)
+	err = startAPIServer(ctx, g, svrCfg, clientCtx, svrCtx, app, cmtCfg.RootDir, grpcSrv, metrics)
 	if err != nil {
 		return err
 	}
@@ -504,7 +505,6 @@ func startGrpcServer(
 func startAPIServer(
 	ctx context.Context,
 	g *errgroup.Group,
-	cmtCfg *cmtcfg.Config,
 	svrCfg serverconfig.Config,
 	clientCtx client.Context,
 	svrCtx *Context,
@@ -612,7 +612,7 @@ func startApp[T types.Application](svrCtx *Context, appCreator types.AppCreator[
 
 	if isTestnet, ok := svrCtx.Viper.Get(KeyIsTestnet).(bool); ok && isTestnet {
 		var appPtr *T
-		appPtr, err = testnetify[T](svrCtx, home, appCreator, db, traceWriter)
+		appPtr, err = testnetify[T](svrCtx, appCreator, db, traceWriter)
 		if err != nil {
 			return app, traceCleanupFn, err
 		}
@@ -639,6 +639,10 @@ func InPlaceTestnetCreator[T types.Application](testnetAppCreator types.AppCreat
 		opts.DBOpener = OpenDB
 	}
 
+	if opts.StartCommandHandler == nil {
+		opts.StartCommandHandler = start
+	}
+
 	cmd := &cobra.Command{
 		Use:   "in-place-testnet [newChainID] [newOperatorAddress]",
 		Short: "Create and start a testnet from current local state",
@@ -703,7 +707,7 @@ you want to test the upgrade handler itself.
 			serverCtx.Viper.Set(KeyNewOpAddr, newOperatorAddress)
 
 			err = wrapCPUProfile(serverCtx, func() error {
-				return start(serverCtx, clientCtx, testnetAppCreator, withCMT, opts)
+				return opts.StartCommandHandler(serverCtx, clientCtx, testnetAppCreator, withCMT, opts)
 			})
 
 			serverCtx.Logger.Debug("received quit signal")
@@ -726,7 +730,7 @@ you want to test the upgrade handler itself.
 
 // testnetify modifies both state and blockStore, allowing the provided operator address and local validator key to control the network
 // that the state in the data folder represents. The chainID of the local genesis file is modified to match the provided chainID.
-func testnetify[T types.Application](ctx *Context, home string, testnetAppCreator types.AppCreator[T], db dbm.DB, traceWriter io.WriteCloser) (*T, error) {
+func testnetify[T types.Application](ctx *Context, testnetAppCreator types.AppCreator[T], db dbm.DB, traceWriter io.WriteCloser) (*T, error) {
 	config := ctx.Config
 
 	newChainID, ok := ctx.Viper.Get(KeyNewChainID).(string)
@@ -772,9 +776,6 @@ func testnetify[T types.Application](ctx *Context, home string, testnetAppCreato
 		return nil, err
 	}
 	validatorAddress := userPubKey.Address()
-	if err != nil {
-		return nil, err
-	}
 
 	stateStore := sm.NewStore(stateDB, sm.StoreOptions{
 		DiscardABCIResponses: config.Storage.DiscardABCIResponses,

server/types/app.go

@@ -8,7 +8,6 @@ import (
 	cmttypes "github.com/cometbft/cometbft/types"
 	dbm "github.com/cosmos/cosmos-db"
 	"github.com/cosmos/gogoproto/grpc"
-	"github.com/spf13/cobra"
 
 	"cosmossdk.io/log"
 	"cosmossdk.io/store/snapshots"
@@ -68,9 +67,6 @@ type (
 	// application using various configurations.
 	AppCreator[T Application] func(log.Logger, dbm.DB, io.Writer, AppOptions) T
 
-	// ModuleInitFlags takes a start command and adds modules specific init flags.
-	ModuleInitFlags func(startCmd *cobra.Command)
-
 	// ExportedApp represents an exported app state, along with
 	// validators, consensus params and latest app height.
 	ExportedApp struct {

server/util.go

@@ -324,7 +324,7 @@ func interceptConfigs(rootViper *viper.Viper, customAppTemplate string, customCo
 }
 
 // AddCommands add server commands
-func AddCommands[T types.Application](rootCmd *cobra.Command, appCreator types.AppCreator[T], addStartFlags types.ModuleInitFlags) {
+func AddCommands[T types.Application](rootCmd *cobra.Command, appCreator types.AppCreator[T], opts StartCmdOptions[T]) {
 	cometCmd := &cobra.Command{
 		Use:     "comet",
 		Aliases: []string{"cometbft", "tendermint"},
@@ -341,11 +341,7 @@ func AddCommands[T types.Application](rootCmd *cobra.Command, appCreator types.A
 		BootstrapStateCmd(appCreator),
 	)
 
-	startCmd := StartCmd(appCreator)
-	if addStartFlags != nil {
-		addStartFlags(startCmd)
-	}
-
+	startCmd := StartCmdWithOptions(appCreator, opts)
 	rootCmd.AddCommand(
 		startCmd,
 		cometCmd,
@@ -354,10 +350,15 @@ func AddCommands[T types.Application](rootCmd *cobra.Command, appCreator types.A
 	)
 }
 
+// AddCommandsWithStartCmdOptions adds server commands with the provided StartCmdOptions.
+// Deprecated: Use AddCommands directly instead.
+func AddCommandsWithStartCmdOptions[T types.Application](rootCmd *cobra.Command, appCreator types.AppCreator[T], opts StartCmdOptions[T]) {
+	AddCommands(rootCmd, appCreator, opts)
+}
+
 // AddTestnetCreatorCommand allows chains to create a testnet from the state existing in their node's data directory.
-func AddTestnetCreatorCommand[T types.Application](rootCmd *cobra.Command, appCreator types.AppCreator[T], addStartFlags types.ModuleInitFlags) {
+func AddTestnetCreatorCommand[T types.Application](rootCmd *cobra.Command, appCreator types.AppCreator[T]) {
 	testnetCreateCmd := InPlaceTestnetCreator(appCreator)
-	addStartFlags(testnetCreateCmd)
 	rootCmd.AddCommand(testnetCreateCmd)
 }
 

simapp/simd/cmd/commands.go

@@ -23,8 +23,6 @@ import (
 	"github.com/cosmos/cosmos-sdk/client/pruning"
 	"github.com/cosmos/cosmos-sdk/client/rpc"
 	"github.com/cosmos/cosmos-sdk/client/snapshot"
-	"github.com/cosmos/cosmos-sdk/codec"
-	codectypes "github.com/cosmos/cosmos-sdk/codec/types"
 	"github.com/cosmos/cosmos-sdk/server"
 	servertypes "github.com/cosmos/cosmos-sdk/server/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -35,8 +33,6 @@ import (
 func initRootCmd(
 	rootCmd *cobra.Command,
 	txConfig client.TxConfig,
-	interfaceRegistry codectypes.InterfaceRegistry,
-	appCodec codec.Codec,
 	moduleManager *module.Manager,
 ) {
 	cfg := sdk.GetConfig()
@@ -51,7 +47,7 @@ func initRootCmd(
 		snapshot.Cmd(newApp),
 	)
 
-	server.AddCommands(rootCmd, newApp, func(startCmd *cobra.Command) {})
+	server.AddCommands(rootCmd, newApp, server.StartCmdOptions[servertypes.Application]{})
 
 	// add keybase, auxiliary RPC, query, genesis, and tx child commands
 	rootCmd.AddCommand(

simapp/simd/cmd/root.go

@@ -110,7 +110,7 @@ func NewRootCmd() *cobra.Command {
 		},
 	}
 
-	initRootCmd(rootCmd, encodingConfig.TxConfig, encodingConfig.InterfaceRegistry, encodingConfig.Codec, tempApp.ModuleManager)
+	initRootCmd(rootCmd, encodingConfig.TxConfig, tempApp.ModuleManager)
 
 	// autocli opts
 	customClientTemplate, customClientConfig := initClientConfig()

simapp/simd/cmd/root_di.go

@@ -87,7 +87,7 @@ func NewRootCmd() *cobra.Command {
 		},
 	}
 
-	initRootCmd(rootCmd, clientCtx.TxConfig, clientCtx.InterfaceRegistry, clientCtx.Codec, moduleManager)
+	initRootCmd(rootCmd, clientCtx.TxConfig, moduleManager)
 
 	if err := autoCliOpts.EnhanceRootCommand(rootCmd); err != nil {
 		panic(err)