feat(server/v2): add min gas price and check with tx fee

server/v2/cometbft/abci.go

@@ -18,6 +18,7 @@ import (
 	"cosmossdk.io/core/transaction"
 	errorsmod "cosmossdk.io/errors"
 	"cosmossdk.io/log"
+	sdkmath "cosmossdk.io/math"
 	"cosmossdk.io/server/v2/appmanager"
 	"cosmossdk.io/server/v2/cometbft/client/grpc/cmtservice"
 	"cosmossdk.io/server/v2/cometbft/handlers"
@@ -27,6 +28,7 @@ import (
 	"cosmossdk.io/server/v2/streaming"
 	"cosmossdk.io/store/v2/snapshots"
 	consensustypes "cosmossdk.io/x/consensus/types"
+	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
 var _ abci.Application = (*Consensus[transaction.Tx])(nil)
@@ -123,6 +125,14 @@ func (c *Consensus[T]) CheckTx(ctx context.Context, req *abciproto.CheckTxReques
 		return nil, err
 	}
 
+	// check tx fee with validator's minimum-gas-price config
+	if err := c.checkTxFeeWithMinGasPrices(decodedTx); err != nil {
+		return &abciproto.CheckTxResponse{
+			Code: 1,
+			Log:  err.Error(),
+		}, nil
+	}
+
 	resp, err := c.app.ValidateTx(ctx, decodedTx)
 	if err != nil {
 		return nil, err
@@ -145,6 +155,40 @@ func (c *Consensus[T]) CheckTx(ctx context.Context, req *abciproto.CheckTxReques
 	return cometResp, nil
 }
 
+// checkTxFeeWithMinGasPrices ensure that the provided fees meet a minimum threshold for the validator,
+// if this is a CheckTx. This is only for local mempool purposes, and thus
+// is only ran on check tx.
+func (c *Consensus[T]) checkTxFeeWithMinGasPrices(tx transaction.Tx) error {
+	feeTx, ok := tx.(sdk.FeeTx)
+	if !ok {
+		return nil // don't force users to implement fee tx
+	}
+
+	feeCoins := feeTx.GetFee()
+	gas := feeTx.GetGas()
+
+	minGasPrices := c.cfg.GetMinGasPrices()
+	if minGasPrices.IsZero() {
+		return nil
+	}
+
+	requiredFees := make(sdk.Coins, len(minGasPrices))
+
+	// Determine the required fees by multiplying each required minimum gas
+	// price by the gas limit, where fee = ceil(minGasPrice * gasLimit).
+	glDec := sdkmath.LegacyNewDec(int64(gas))
+	for i, gp := range minGasPrices {
+		fee := gp.Amount.Mul(glDec)
+		requiredFees[i] = sdk.NewCoin(gp.Denom, fee.Ceil().RoundInt())
+	}
+
+	if !feeCoins.IsAnyGTE(requiredFees) {
+		return errorsmod.Wrapf(cometerrors.ErrInsufficientFee, "insufficient fees; got: %s required: %s", feeCoins, requiredFees)
+	}
+
+	return nil
+}
+
 // Info implements types.Application.
 func (c *Consensus[T]) Info(ctx context.Context, _ *abciproto.InfoRequest) (*abciproto.InfoResponse, error) {
 	version, _, err := c.store.StateLatest()

server/v2/cometbft/config.go

@@ -1,10 +1,14 @@
 package cometbft
 
 import (
+	"fmt"
+
 	cmtcfg "github.com/cometbft/cometbft/config"
 	"github.com/spf13/viper"
 
 	serverv2 "cosmossdk.io/server/v2"
+	cometerrors "cosmossdk.io/server/v2/cometbft/types/errors"
+	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
 // Config is the configuration for the CometBFT application
@@ -27,6 +31,7 @@ func DefaultAppTomlConfig() *AppTomlConfig {
 }
 
 type AppTomlConfig struct {
+	MinGasPrices    string   `mapstructure:"minimum-gas-prices" toml:"minimum-gas-prices" comment:"minimum-gas-prices defines the price which a validator is willing to accept for processing a transaction. A transaction's fees must meet the minimum of any denomination specified in this config (e.g. 0.25token1;0.0001token2)."`
 	MinRetainBlocks uint64   `mapstructure:"min-retain-blocks" toml:"min-retain-blocks" comment:"min-retain-blocks defines the minimum block height offset from the current block being committed, such that all blocks past this offset are pruned from CometBFT. A value of 0 indicates that no blocks should be pruned."`
 	IndexEvents     []string `mapstructure:"index-events" toml:"index-events" comment:"index-events defines the set of events in the form {eventType}.{attributeKey}, which informs CometBFT what to index. If empty, all events will be indexed."`
 	HaltHeight      uint64   `mapstructure:"halt-height" toml:"halt-height" comment:"halt-height contains a non-zero block height at which a node will gracefully halt and shutdown that can be used to assist upgrades and testing."`
@@ -64,3 +69,27 @@ func getConfigTomlFromViper(v *viper.Viper) *cmtcfg.Config {
 
 	return conf.SetRoot(rootDir)
 }
+
+// GetMinGasPrices returns the validator's minimum gas prices based on the set configuration.
+func (c Config) GetMinGasPrices() sdk.DecCoins {
+	minGasPricesStr := c.AppTomlConfig.MinGasPrices
+	if minGasPricesStr == "" {
+		return sdk.DecCoins{}
+	}
+
+	gasPrices, err := sdk.ParseDecCoins(minGasPricesStr)
+	if err != nil {
+		panic(fmt.Sprintf("invalid minimum gas prices: %v", err))
+	}
+
+	return gasPrices
+}
+
+// ValidateBasic returns an error if min-gas-prices field is empty in Config. Otherwise, it returns nil.
+func (c Config) ValidateBasic() error {
+	if c.AppTomlConfig.MinGasPrices == "" {
+		return cometerrors.ErrAppConfig.Wrap("set minimum-gas-prices in app.toml or flag or env variable")
+	}
+
+	return nil
+}

server/v2/cometbft/flags.go

@@ -51,10 +51,11 @@ func prefix(f string) string {
 
 // Server flags
 var (
-	Standalone     = prefix("standalone")
-	FlagAddress    = prefix("address")
-	FlagTransport  = prefix("transport")
-	FlagHaltHeight = prefix("halt-height")
-	FlagHaltTime   = prefix("halt-time")
-	FlagTrace      = prefix("trace")
+	Standalone       = prefix("standalone")
+	FlagAddress      = prefix("address")
+	FlagTransport    = prefix("transport")
+	FlagHaltHeight   = prefix("halt-height")
+	FlagHaltTime     = prefix("halt-time")
+	FlagTrace        = prefix("trace")
+	FlagMinGasPrices = prefix("minimum-gas-prices")
 )

server/v2/cometbft/go.mod

@@ -25,6 +25,7 @@ require (
 	cosmossdk.io/core v0.12.1-0.20240725072823-6a2d039e1212
 	cosmossdk.io/errors v1.0.1
 	cosmossdk.io/log v1.3.1
+	cosmossdk.io/math v1.3.0
 	cosmossdk.io/server/v2 v2.0.0-00010101000000-000000000000
 	cosmossdk.io/server/v2/appmanager v0.0.0-00010101000000-000000000000
 	cosmossdk.io/store/v2 v2.0.0-00010101000000-000000000000
@@ -50,7 +51,6 @@ require (
 	cosmossdk.io/collections v0.4.0 // indirect
 	cosmossdk.io/depinject v1.0.0 // indirect
 	cosmossdk.io/errors/v2 v2.0.0-20240731132947-df72853b3ca5 // indirect
-	cosmossdk.io/math v1.3.0 // indirect
 	cosmossdk.io/store v1.1.1-0.20240418092142-896cdf1971bc // indirect
 	cosmossdk.io/x/auth v0.0.0-00010101000000-000000000000 // indirect
 	cosmossdk.io/x/bank v0.0.0-20240226161501-23359a0b6d91 // indirect

server/v2/cometbft/server.go

@@ -130,6 +130,11 @@ func (s *CometBFTServer[T]) Name() string {
 }
 
 func (s *CometBFTServer[T]) Start(ctx context.Context) error {
+	// validate cometbft config
+	if err := s.config.ValidateBasic(); err != nil {
+		return err
+	}
+
 	wrappedLogger := cometlog.CometLoggerWrapper{Logger: s.logger}
 	if s.config.AppTomlConfig.Standalone {
 		svr, err := abciserver.NewServer(s.config.AppTomlConfig.Address, s.config.AppTomlConfig.Transport, s.Consensus)
@@ -218,6 +223,7 @@ func (s *CometBFTServer[T]) StartCmdFlags() *pflag.FlagSet {
 	flags.String(FlagTransport, "socket", "Transport protocol: socket, grpc")
 	flags.Uint64(FlagHaltHeight, 0, "Block height at which to gracefully halt the chain and shutdown the node")
 	flags.Uint64(FlagHaltTime, 0, "Minimum block time (in Unix seconds) at which to gracefully halt the chain and shutdown the node")
+	flags.String(FlagMinGasPrices, "", "Minimum gas prices to accept for transactions; Any fee in a tx must meet this minimum (e.g. 0.01photino;0.0001stake)")
 	flags.Bool(FlagTrace, false, "Provide full stack traces for errors in ABCI Log")
 	flags.Bool(Standalone, false, "Run app without CometBFT")
 

server/v2/cometbft/types/errors/errors.go

@@ -14,4 +14,13 @@ var (
 	// ErrInvalidRequest defines an ABCI typed error where the request contains
 	// invalid data.
 	ErrInvalidRequest = errorsmod.Register(RootCodespace, 2, "invalid request")
+
+	// ErrTxDecode is returned if we cannot parse a transaction
+	ErrTxDecode = errorsmod.Register(RootCodespace, 3, "tx parse error")
+
+	// ErrInsufficientFee is returned if provided fee in tx is less than required fee
+	ErrInsufficientFee = errorsmod.Register(RootCodespace, 4, "insufficient fee")
+
+	// ErrAppConfig defines an error occurred if application configuration is misconfigured
+	ErrAppConfig = errorsmod.Register(RootCodespace, 5, "error in app.toml")
 )

server/v2/config.go

@@ -7,6 +7,30 @@ import (
 	"github.com/spf13/viper"
 )
 
+// ServerConfig defines configuration for the main server.
+type ServerConfig struct {
+	MinGasPrices string `mapstructure:"minimum-gas-prices" toml:"minimum-gas-prices" comment:"minimum-gas-prices defines the price which a validator is willing to accept for processing a transaction. A transaction's fees must meet the minimum of any denomination specified in this config (e.g. 0.25token1;0.0001token2)."`
+}
+
+// ValidateBasic returns an error if min-gas-prices field is empty in Config. Otherwise, it returns nil.
+func (c ServerConfig) ValidateBasic() error {
+	if c.MinGasPrices == "" {
+		return fmt.Errorf("error in app.toml: set minimum-gas-prices in app.toml or flag or env variable")
+	}
+
+	return nil
+}
+
+// DefaultMainServerConfig returns the default config of main server component
+func DefaultMainServerConfig() ServerConfig {
+	return ServerConfig{}
+}
+
+// OverwriteDefaultConfig overwrites main server config with given config
+func (s *Server[T]) OverwriteDefaultConfig(cfg ServerConfig) {
+	s.config = cfg
+}
+
 // ReadConfig returns a viper instance of the config file
 func ReadConfig(configPath string) (*viper.Viper, error) {
 	v := viper.New()

server/v2/flags.go

@@ -1,6 +1,17 @@
 // Package serverv2 defines constants for server configuration flags and output formats.
 package serverv2
 
+import "fmt"
+
+// start flags are prefixed with the server name
+// as the config in prefixed with the server name
+// this allows viper to properly bind the flags
+func prefix(f string) string {
+	return fmt.Sprintf("%s.%s", serverName, f)
+}
+
+var FlagMinGasPrices = prefix("minimum-gas-prices")
+
 const (
 	// FlagHome specifies the home directory flag.
 	FlagHome = "home"

server/v2/server.go

@@ -56,11 +56,16 @@ type CLIConfig struct {
 	Txs []*cobra.Command
 }
 
+const (
+	serverName = "server"
+)
+
 var _ ServerComponent[transaction.Tx] = (*Server[transaction.Tx])(nil)
 
 type Server[T transaction.Tx] struct {
 	logger     log.Logger
 	components []ServerComponent[T]
+	config     ServerConfig
 }
 
 func NewServer[T transaction.Tx](
@@ -74,11 +79,16 @@ func NewServer[T transaction.Tx](
 }
 
 func (s *Server[T]) Name() string {
-	return "server"
+	return serverName
 }
 
 // Start starts all components concurrently.
 func (s *Server[T]) Start(ctx context.Context) error {
+	// validate main server config
+	if err := s.config.ValidateBasic(); err != nil {
+		return err
+	}
+
 	s.logger.Info("starting servers...")
 
 	g, ctx := errgroup.WithContext(ctx)
@@ -151,9 +161,19 @@ func (s *Server[T]) CLICommands() CLIConfig {
 	return commands
 }
 
+// Config returns config of the main server component
+func (s *Server[T]) Config() ServerConfig {
+	return s.config
+}
+
 // Configs returns all configs of all server components.
 func (s *Server[T]) Configs() map[string]any {
 	cfgs := make(map[string]any)
+
+	// add main server component config
+	cfgs[s.Name()] = s.config
+
+	// add other components' config
 	for _, mod := range s.components {
 		if configmod, ok := mod.(HasConfig); ok {
 			cfg := configmod.Config()
@@ -164,9 +184,22 @@ func (s *Server[T]) Configs() map[string]any {
 	return cfgs
 }
 
+func (s *Server[T]) StartCmdFlags() *pflag.FlagSet {
+	flags := pflag.NewFlagSet(s.Name(), pflag.ExitOnError)
+	flags.String(FlagMinGasPrices, "", "Minimum gas prices to accept for transactions; Any fee in a tx must meet this minimum (e.g. 0.01photino;0.0001stake)")
+	return flags
+}
+
 // Init initializes all server components with the provided application, configuration, and logger.
 // It returns an error if any component fails to initialize.
 func (s *Server[T]) Init(appI AppI[T], v *viper.Viper, logger log.Logger) error {
+	cfg := s.config
+	if v != nil {
+		if err := UnmarshalSubConfig(v, s.Name(), &cfg); err != nil {
+			return fmt.Errorf("failed to unmarshal config: %w", err)
+		}
+	}
+
 	var components []ServerComponent[T]
 	for _, mod := range s.components {
 		mod := mod
@@ -177,6 +210,7 @@ func (s *Server[T]) Init(appI AppI[T], v *viper.Viper, logger log.Logger) error
 		components = append(components, mod)
 	}
 
+	s.config = cfg
 	s.components = components
 	return nil
 }
@@ -217,6 +251,11 @@ func (s *Server[T]) WriteConfig(configPath string) error {
 // StartFlags returns all flags of all server components.
 func (s *Server[T]) StartFlags() []*pflag.FlagSet {
 	flags := []*pflag.FlagSet{}
+
+	// add main server component flags
+	flags = append(flags, s.StartCmdFlags())
+
+	// add other components' start cmd flags
 	for _, mod := range s.components {
 		if startmod, ok := mod.(HasStartFlags); ok {
 			flags = append(flags, startmod.StartCmdFlags())

simapp/v2/simdv2/cmd/commands.go

@@ -70,12 +70,33 @@ func initRootCmd[T transaction.Tx](
 		offchain.OffChain(),
 	)
 
+	// Optionally allow the chain developer to overwrite the cometbft default
+	// app toml config.
+	cometAppTomlCfg := cometbft.DefaultAppTomlConfig()
+	// The cometbft server's default minimum gas price is set to "" (empty value) inside
+	// app.toml. If left empty by validators, the node will halt on startup.
+	// However, the chain developer can set a default app.toml value for their
+	// validators here.
+	//
+	// In summary:
+	// - if you leave cometAppTomlCfg.MinGasPrices = "", all validators MUST tweak their
+	//   own app.toml config,
+	// - if you set cometAppTomlCfg.MinGasPrices non-empty, validators CAN tweak their
+	//   own app.toml to override, or use this default value.
+	//
+	// In simapp, we set the min gas prices to 0.
+	cometAppTomlCfg.MinGasPrices = "0stake"
+
 	// wire server commands
 	if err = serverv2.AddCommands(
 		rootCmd,
 		newApp,
 		logger,
-		cometbft.New(&genericTxDecoder[T]{txConfig}, cometbft.DefaultServerOptions[T]()),
+		cometbft.New(
+			&genericTxDecoder[T]{txConfig},
+			cometbft.DefaultServerOptions[T](),
+			cometbft.OverwriteDefaultAppTomlConfig(cometAppTomlCfg),
+		),
 		grpc.New[T](),
 		store.New[T](),
 	); err != nil {

simapp/v2/simdv2/cmd/testnet.go

@@ -337,6 +337,9 @@ func initTestnetFiles[T transaction.Tx](
 			return err
 		}
 
+		serverCfg := serverv2.DefaultMainServerConfig()
+		serverCfg.MinGasPrices = args.minGasPrices
+
 		// Write server config
 		cometServer := cometbft.New[T](
 			&genericTxDecoder[T]{clientCtx.TxConfig},
@@ -346,6 +349,7 @@ func initTestnetFiles[T transaction.Tx](
 		grpcServer := grpc.New[T](grpc.OverwriteDefaultConfig(grpcConfig))
 		storeServer := store.New[T]()
 		server := serverv2.NewServer(log.NewNopLogger(), cometServer, grpcServer, storeServer)
+		server.OverwriteDefaultConfig(serverCfg)
 		err = server.WriteConfig(filepath.Join(nodeDir, "config"))
 		if err != nil {
 			return err

tools/confix/data/v2-app.toml

@@ -1,4 +1,6 @@
 [comet]
+# minimum-gas-prices defines the price which a validator is willing to accept for processing a transaction. A transaction's fees must meet the minimum of any denomination specified in this config (e.g. 0.25token1;0.0001token2).
+minimum-gas-prices = '0stake'
 # min-retain-blocks defines the minimum block height offset from the current block being committed, such that all blocks past this offset are pruned from CometBFT. A value of 0 indicates that no blocks should be pruned.
 min-retain-blocks = 0
 # index-events defines the set of events in the form {eventType}.{attributeKey}, which informs CometBFT what to index. If empty, all events will be indexed.