load config file via viper

config.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"fmt"
+	"github.com/fsnotify/fsnotify"
+	"time"
+
+	"github.com/spf13/viper"
+	_ "github.com/spf13/viper/remote"
+)
+
+func loadConfigFile(configType, configLocation, consulKey string) {
+	setDefaults()
+	if configLocation == "" {
+		return
+	}
+
+	switch configType {
+	case "local":
+		viper.SetConfigName("config")
+		viper.AddConfigPath(configLocation)
+
+		err := viper.ReadInConfig()
+		if err != nil {
+			panic(fmt.Errorf("Fatal error config file: %s \n", err))
+		}
+
+		viper.WatchConfig()
+
+	}
+
+	viper.OnConfigChange(func(e fsnotify.Event) {
+		fmt.Println("Config file changed:", e.Name)
+	})
+}
+
+func setDefaults() {
+	viper.SetDefault("server.port", 3000)
+	viper.SetDefault("backends.numConns", 3)
+	viper.SetDefault("metrics.port", 8080)
+}

config.yml.example

@@ -0,0 +1,15 @@
+metrics:
+  port: 8080
+
+server:
+  port: 3001
+  cacert: ''
+  privkey: ''
+
+cache:
+  enabled: true
+
+backends: 
+  hosts: []
+  numConns: 3
+

go.mod

@@ -6,10 +6,12 @@ require (
 	github.com/OneOfOne/xxhash v1.2.8 // indirect
 	github.com/dgraph-io/ristretto v0.0.3
 	github.com/dgryski/go-farm v0.0.0-20200201041132-a6ae2369ad13 // indirect
+	github.com/fsnotify/fsnotify v1.4.7
 	github.com/kr/text v0.2.0 // indirect
 	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
 	github.com/prometheus/client_golang v1.7.1
 	github.com/spaolacci/murmur3 v1.1.0 // indirect
+	github.com/spf13/viper v1.7.1
 	github.com/stretchr/testify v1.6.1 // indirect
 	golang.org/x/sys v0.0.0-20200625212154-ddb9806d33ae // indirect
 	google.golang.org/protobuf v1.25.0 // indirect