R4R: Add validate-genesis command

PENDING.md

@@ -5,6 +5,7 @@ BREAKING CHANGES
 * Gaia REST API (`gaiacli advanced rest-server`)
 
 * Gaia CLI  (`gaiacli`)
+  - [#3399](https://github.com/cosmos/cosmos-sdk/pull/3399) Add `gaiad validate-genesis` command to facilitate checking of genesis files
 
 * Gaia
 

cmd/gaia/cmd/gaiad/main.go

@@ -43,6 +43,7 @@ func main() {
 	rootCmd.AddCommand(gaiaInit.TestnetFilesCmd(ctx, cdc))
 	rootCmd.AddCommand(gaiaInit.GenTxCmd(ctx, cdc))
 	rootCmd.AddCommand(gaiaInit.AddGenesisAccountCmd(ctx, cdc))
+	rootCmd.AddCommand(gaiaInit.ValidateGenesisCmd(ctx, cdc))
 	rootCmd.AddCommand(client.NewCompletionCmd(rootCmd, true))
 
 	server.AddCommands(ctx, cdc, rootCmd, newApp, exportAppStateAndTMValidators)

cmd/gaia/init/validate_genesis.go

@@ -0,0 +1,48 @@
+package init
+
+import (
+	"fmt"
+
+	"github.com/cosmos/cosmos-sdk/cmd/gaia/app"
+	"github.com/cosmos/cosmos-sdk/codec"
+	"github.com/cosmos/cosmos-sdk/server"
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+	"github.com/tendermint/tendermint/types"
+)
+
+// Validate genesis command takes
+func ValidateGenesisCmd(ctx *server.Context, cdc *codec.Codec) *cobra.Command {
+	return &cobra.Command{
+		Use:   "validate-genesis [file]",
+		Args:  cobra.RangeArgs(0, 1),
+		Short: "validates the genesis file at the default location or at the location passed as an arg",
+		RunE: func(cmd *cobra.Command, args []string) (err error) {
+			var genesis string
+			var genDoc types.GenesisDoc
+			var genstate app.GenesisState
+
+			// Load default if passed no args, otherwise load passed file
+			if len(args) == 0 {
+				genesis = ctx.Config.GenesisFile()
+			} else {
+				genesis = args[0]
+			}
+
+			if genDoc, err = loadGenesisDoc(cdc, genesis); err != nil {
+				return errors.Errorf("Error loading genesis doc from %s: %s", genesis, err.Error())
+			}
+
+			if err = cdc.UnmarshalJSON(genDoc.AppState, &genstate); err != nil {
+				return errors.Errorf("Error unmarshaling genesis doc %s: %s", genesis, err.Error())
+			}
+
+			if err = app.GaiaValidateGenesisState(genstate); err != nil {
+				return errors.Errorf("Error validating genesis file %s: %s", genesis, err.Error())
+			}
+
+			fmt.Printf("File at %s is a valid genesis file for gaiad\n", genesis)
+			return nil
+		},
+	}
+}