Automatically determine chainID, throw error if not provided (closes #810)

client/context/viper.go

@@ -1,9 +1,13 @@
 package context
 
 import (
+	"encoding/json"
 	"github.com/spf13/viper"
+	"io/ioutil"
 
+	tcmd "github.com/tendermint/tendermint/cmd/tendermint/commands"
 	rpcclient "github.com/tendermint/tendermint/rpc/client"
+	tmtypes "github.com/tendermint/tendermint/types"
 
 	"github.com/cosmos/cosmos-sdk/client"
 	"github.com/cosmos/cosmos-sdk/client/core"
@@ -15,8 +19,24 @@ func NewCoreContextFromViper() core.CoreContext {
 	if nodeURI != "" {
 		rpc = rpcclient.NewHTTP(nodeURI, "/websocket")
 	}
+	chainID := viper.GetString(client.FlagChainID)
+	// if chain ID is not specified manually, read chain ID from genesis file if present
+	if chainID == "" {
+		cfg, err := tcmd.ParseConfig()
+		if err == nil {
+			genesisFile := cfg.GenesisFile()
+			bz, err := ioutil.ReadFile(genesisFile)
+			if err == nil {
+				var doc tmtypes.GenesisDoc
+				err = json.Unmarshal(bz, &doc)
+				if err == nil {
+					chainID = doc.ChainID
+				}
+			}
+		}
+	}
 	return core.CoreContext{
-		ChainID:         viper.GetString(client.FlagChainID),
+		ChainID:         chainID,
 		Height:          viper.GetInt64(client.FlagHeight),
 		TrustNode:       viper.GetBool(client.FlagTrustNode),
 		FromAddressName: viper.GetString(client.FlagName),

client/core/core.go

@@ -91,6 +91,9 @@ func (ctx CoreContext) SignAndBuild(name, passphrase string, msg sdk.Msg, cdc *w
 
 	// build the Sign Messsage from the Standard Message
 	chainID := ctx.ChainID
+	if chainID == "" {
+		return nil, errors.Errorf("Chain ID required but not specified")
+	}
 	sequence := ctx.Sequence
 	signMsg := sdk.StdSignMsg{
 		ChainID:   chainID,