fee suggestion for construction/metadata

server/config/config.go

@@ -125,6 +125,12 @@ type RosettaConfig struct {
 
 	// Offline defines if the server must be run in offline mode
 	Offline bool `mapstructure:"offline"`
+
+	// SuggestGas defines gas limit when calculate fee
+	SuggestGas int `mapstructure:"suggest-gas"`
+
+	// DefaultSuggestDenom defines the defult denom for fee suggestion
+	DefaultSuggestDenom string `mapstructure:"default-suggest-denom"`
 }
 
 // GRPCConfig defines configuration for the gRPC server.
@@ -292,12 +298,14 @@ func GetConfig(v *viper.Viper) Config {
 			EnableUnsafeCORS:   v.GetBool("api.enabled-unsafe-cors"),
 		},
 		Rosetta: RosettaConfig{
-			Enable:     v.GetBool("rosetta.enable"),
-			Address:    v.GetString("rosetta.address"),
-			Blockchain: v.GetString("rosetta.blockchain"),
-			Network:    v.GetString("rosetta.network"),
-			Retries:    v.GetInt("rosetta.retries"),
-			Offline:    v.GetBool("rosetta.offline"),
+			Enable:              v.GetBool("rosetta.enable"),
+			Address:             v.GetString("rosetta.address"),
+			Blockchain:          v.GetString("rosetta.blockchain"),
+			Network:             v.GetString("rosetta.network"),
+			Retries:             v.GetInt("rosetta.retries"),
+			Offline:             v.GetBool("rosetta.offline"),
+			SuggestGas:          v.GetInt("rosetta.suggest-gas"),
+			DefaultSuggestDenom: v.GetString("rosetta.default-suggest-denom"),
 		},
 		GRPC: GRPCConfig{
 			Enable:  v.GetBool("grpc.enable"),

server/rosetta/client_online.go

@@ -395,6 +395,25 @@ func (c *Client) ConstructionMetadataFromOptions(ctx context.Context, options ma
 		return nil, err
 	}
 
+	if constructionOptions.GasLimit <= 0 {
+		// set to default
+		constructionOptions.GasLimit = uint64(c.config.SuggestGas)
+	}
+	if constructionOptions.GasPrice == "" {
+		// set to default
+		denom := c.config.DefaultSuggestDenom
+		constructionOptions.GasPrice = c.config.SuggestPrices.AmountOf(denom).String() + denom
+	} else {
+		gasPrice, err := sdk.ParseDecCoin(constructionOptions.GasPrice)
+		if err != nil {
+			return nil, err
+		}
+		// check gasPrice is in the list
+		if !c.config.SuggestPrices.AmountOf(gasPrice.Denom).IsPositive() {
+			return nil, crgerrs.ErrBadArgument
+		}
+	}
+
 	signersData := make([]*SignerData, len(constructionOptions.ExpectedSigners))
 
 	for i, signer := range constructionOptions.ExpectedSigners {

server/rosetta/config.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/codec"
 	codectypes "github.com/cosmos/cosmos-sdk/codec/types"
+	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
 // configuration defaults constants
@@ -30,6 +31,8 @@ const (
 	DefaultNetwork = "network"
 	// DefaultOffline defines the default offline value
 	DefaultOffline = false
+	// DefaultSuggestGas defines the default gas limit for fee suggestion
+	DefaultSuggestGas = 20_000
 )
 
 // configuration flags
@@ -65,6 +68,12 @@ type Config struct {
 	Retries int
 	// Offline defines if the server must be run in offline mode
 	Offline bool
+	// SuggestGas defines the gas limit for fee suggestion
+	SuggestGas int
+	// DefaultSuggestDenom defines the default denom for fee suggestion
+	DefaultSuggestDenom string
+	// SuggestPrices defines the gas prices for fee suggestion
+	SuggestPrices sdk.DecCoins
 	// Codec overrides the default data and construction api client codecs
 	Codec *codec.ProtoCodec
 	// InterfaceRegistry overrides the default data and construction api interface registry
@@ -102,6 +111,19 @@ func (c *Config) validate() error {
 	if c.Offline {
 		return fmt.Errorf("offline mode is not supported for stargate implementation due to how sigv2 works")
 	}
+	if c.SuggestGas <= 0 {
+		c.SuggestGas = DefaultSuggestGas
+	}
+	found := false
+	for i := 0; i < c.SuggestPrices.Len(); i++ {
+		if c.SuggestPrices.GetDenomByIndex(i) == c.DefaultSuggestDenom {
+			found = true
+			break
+		}
+	}
+	if !found {
+		return fmt.Errorf("default suggest denom is not found in minimum-gas-prices")
+	}
 
 	// these are optional but it must be online
 	if c.GRPCEndpoint == "" {

server/rosetta/lib/internal/service/construction.go

@@ -9,6 +9,7 @@ import (
 	"github.com/coinbase/rosetta-sdk-go/types"
 
 	"github.com/cosmos/cosmos-sdk/server/rosetta/lib/errors"
+	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
 // ConstructionCombine Combine creates a network-specific transaction from an unsigned transaction
@@ -69,8 +70,24 @@ func (on OnlineNetwork) ConstructionMetadata(ctx context.Context, request *types
 		return nil, errors.ToRosetta(err)
 	}
 
+	price, err := sdk.ParseDecCoin(metadata["gas_price"].(string))
+	if err != nil {
+		return nil, errors.ToRosetta(err)
+	}
+	gas := sdk.NewIntFromUint64(uint64(metadata["gas_limit"].(float64)))
+
+	suggestedFee := types.Amount{
+		Value: price.Amount.MulInt64(gas.Int64()).String(),
+		Currency: &(types.Currency{
+			Symbol:   price.Denom,
+			Decimals: 0,
+		}),
+		/*metadata*/
+	}
+
 	return &types.ConstructionMetadataResponse{
-		Metadata: metadata,
+		Metadata:     metadata,
+		SuggestedFee: []*types.Amount{&suggestedFee},
 	}, nil
 }
 

server/start.go

@@ -29,6 +29,7 @@ import (
 	crgserver "github.com/cosmos/cosmos-sdk/server/rosetta/lib/server"
 	"github.com/cosmos/cosmos-sdk/server/types"
 	storetypes "github.com/cosmos/cosmos-sdk/store/types"
+	sdktypes "github.com/cosmos/cosmos-sdk/types"
 )
 
 // Tendermint full-node start flags
@@ -340,14 +341,23 @@ func startInProcess(ctx *Context, clientCtx client.Context, appCreator types.App
 			offlineMode = true
 		}
 
+		minGasPrices, err := sdktypes.ParseDecCoins(config.MinGasPrices)
+		if err != nil {
+			ctx.Logger.Error("failed to parse minimum-gas-prices: ", err)
+			return err
+		}
+
 		conf := &rosetta.Config{
-			Blockchain:    config.Rosetta.Blockchain,
-			Network:       config.Rosetta.Network,
-			TendermintRPC: ctx.Config.RPC.ListenAddress,
-			GRPCEndpoint:  config.GRPC.Address,
-			Addr:          config.Rosetta.Address,
-			Retries:       config.Rosetta.Retries,
-			Offline:       offlineMode,
+			Blockchain:          config.Rosetta.Blockchain,
+			Network:             config.Rosetta.Network,
+			TendermintRPC:       ctx.Config.RPC.ListenAddress,
+			GRPCEndpoint:        config.GRPC.Address,
+			Addr:                config.Rosetta.Address,
+			Retries:             config.Rosetta.Retries,
+			Offline:             offlineMode,
+			SuggestGas:          config.Rosetta.SuggestGas,
+			DefaultSuggestDenom: config.Rosetta.DefaultSuggestDenom,
+			SuggestPrices:       minGasPrices.Sort(),
 		}
 		conf.WithCodec(clientCtx.InterfaceRegistry, clientCtx.Codec.(*codec.ProtoCodec))