fix default min gas price

cmd/babylond/cmd/custom_babylon_config.go

@@ -1,11 +1,11 @@
 package cmd
 
 import (
+	"fmt"
+
 	wasmtypes "github.com/CosmWasm/wasmd/x/wasm/types"
 
-	sdkmath "cosmossdk.io/math"
 	serverconfig "github.com/cosmos/cosmos-sdk/server/config"
-	sdk "github.com/cosmos/cosmos-sdk/types"
 
 	appparams "github.com/babylonlabs-io/babylon/app/params"
 	bbn "github.com/babylonlabs-io/babylon/types"
@@ -31,19 +31,9 @@ type BabylonAppConfig struct {
 
 func DefaultBabylonAppConfig() *BabylonAppConfig {
 	baseConfig := *serverconfig.DefaultConfig()
-	// The SDK'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 srvCfg.MinGasPrices = "", all validators MUST tweak their
-	//   own app.toml config,
-	// - if you set srvCfg.MinGasPrices non-empty, validators CAN tweak their
-	//   own app.toml to override, or use this default value.
-	//
-	// In app, we set the min gas prices to 0.
-	baseConfig.MinGasPrices = sdk.NewCoin(appparams.BaseCoinUnit, sdkmath.NewInt(1)).String()
+	// The SDK's default minimum gas price is set to "0.002ubbn" (empty value) inside
+	// app.toml, in order to avoid spamming attacks due to transactions with 0 gas price.
+	baseConfig.MinGasPrices = fmt.Sprintf("%f%s", appparams.GlobalMinGasPrice, appparams.BaseCoinUnit)
 	return &BabylonAppConfig{
 		Config:    baseConfig,
 		Wasm:      wasmtypes.DefaultWasmConfig(),