Add viper configuration

main.go

@@ -1,11 +1,15 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
 )
 
+var cfgFile string
+
 var rootCmd = &cobra.Command{
 	Use:   "chonozinc [description]",
 	Short: "Test and time your minizinc models!",
@@ -16,8 +20,34 @@ var rootCmd = &cobra.Command{
 	Run: func(cmd *cobra.Command, args []string) {},
 }
 
+// initConfig reads in config file and ENV variables if set.
+func initConfig() {
+	if cfgFile != "" { // enable ability to specify config file via flag
+		viper.SetConfigFile(cfgFile)
+	}
+
+	viper.SetConfigName("config")                   // name of config file (without extension)
+	viper.AddConfigPath("$HOME/.config/chronozinc") // adding home directory as first search path
+	viper.SetEnvPrefix("czn")                       // set environment prefix
+	viper.AutomaticEnv()                            // read in environment variables that match
+
+	// If a config file is found, read it in.
+	if err := viper.ReadInConfig(); err == nil {
+		fmt.Println("Using config file:", viper.ConfigFileUsed())
+	} else {
+		fmt.Println("No config file found; using ENV and defaults")
+	}
+}
+
 func main() {
 	if err := rootCmd.Execute(); err != nil {
+		fmt.Println(err)
 		os.Exit(-1)
 	}
 }
+
+func init() {
+	cobra.OnInitialize(initConfig)
+
+	rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.test.yaml)")
+}