Basic cobra/viper cli framework

cmd/root.go

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+// Copyright © 2017 Ethan Frey
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+)
+
+var (
+	rootDir string
+)
+
+// RootCmd represents the base command when called without any subcommands
+var RootCmd = &cobra.Command{
+	Use:   "keys",
+	Short: "Key manager for tendermint clients",
+	Long: `Keys allows you to manage your local keystore for tendermint.
+
+These keys may be in any format supported by go-crypto and can be
+used by light-clients, full nodes, or any other application that
+needs to sign with a private key.`,
+	PersistentPreRunE: bindFlags,
+	// Uncomment the following line if your bare application
+	// has an action associated with it:
+	//	Run: func(cmd *cobra.Command, args []string) { },
+}
+
+// Execute adds all child commands to the root command sets flags appropriately.
+// This is called by main.main(). It only needs to happen once to the rootCmd.
+func Execute() {
+	if err := RootCmd.Execute(); err != nil {
+		fmt.Println(err)
+		os.Exit(-1)
+	}
+}
+
+func init() {
+	cobra.OnInitialize(initEnv)
+	RootCmd.PersistentFlags().StringP("root", "r", os.ExpandEnv("$HOME/.tlc"), "root directory for config and data (default is $HOME/.tlc)")
+}
+
+// initEnv sets to use ENV variables if set.
+func initEnv() {
+	// env variables with TM prefix (eg. TM_ROOT)
+	viper.SetEnvPrefix("TM")
+	viper.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
+	viper.AutomaticEnv()
+}
+
+func bindFlags(cmd *cobra.Command, args []string) error {
+	// cmd.Flags() includes flags from this command and all persistent flags from the parent
+	if err := viper.BindPFlags(cmd.Flags()); err != nil {
+		return err
+	}
+
+	// rootDir is command line flag, env variable, or default $HOME/.tlc
+	rootDir = viper.GetString("root")
+	viper.SetConfigName("keys")  // name of config file (without extension)
+	viper.AddConfigPath(rootDir) // search root directory
+
+	// If a config file is found, read it in.
+	if err := viper.ReadInConfig(); err == nil {
+		fmt.Println("Using config file:", viper.ConfigFileUsed())
+	}
+
+	return nil
+}