command line flag overrides for addresses, secrets, config dump

config/load.go

@@ -1,7 +1,6 @@
 package config
 
 import (
-	"encoding/json"
 	"fmt"
 	"log"
 	"path"
@@ -10,10 +9,46 @@ import (
 	"time"
 
 	"github.com/spf13/viper"
+	flag "github.com/spf13/pflag"
 )
 
-func Load(filename string) (*Config, error) {
-	v    := viper.New()
+func Load(args []string) (cfg *Config, showVersion bool) {
+	showVersion, filename, configdebug, v := FromFlags(args)
+	if showVersion {
+		return nil, true
+	}
+
+	cfg, err := FromFile(v, filename)
+	if err != nil {
+		log.Fatal("[FATAL] ", err)
+	}
+	if configdebug {
+		v.Debug()
+	}
+	return cfg, false
+}
+
+func FromFlags(args []string) (showVersion bool, cfgPath string, configdebug bool, v *viper.Viper) {
+	v   = viper.New()
+	fs := flag.NewFlagSet("default", flag.ExitOnError)
+
+	fs.BoolVar(&showVersion, "version",     false, "show version")
+	fs.StringVar(&cfgPath,   "cfg",         "",    "path to config file")
+	fs.BoolVar(&configdebug, "configdebug", false, "print config to console for debugging")
+
+	fs.String("registry.consul.addr",  "", "Consul address")
+	fs.String("registry.consul.token", "", "Consul token")
+	fs.String("proxy.addr",            "", "proxy address")
+	fs.String("proxy.localip",         "", "proxy local IP")
+	fs.String("proxy.header.clientip", "", "proxy header client IP")
+	fs.String("ui.addr",               "", "UI address")
+
+	v.BindPFlags(fs)
+	fs.Parse(args)
+	return showVersion, cfgPath, configdebug, v
+}
+
+func FromFile(v *viper.Viper, filename string) (*Config, error) {
 	base := path.Base(filename)
 	ext  := path.Ext(filename)
 	name := strings.TrimSuffix(base, ext)
@@ -84,18 +119,9 @@ func FromViper(v *viper.Viper) (cfg *Config, err error) {
 		cfg.Runtime.GOMAXPROCS = runtime.NumCPU()
 	}
 
-	dump(cfg)
 	return cfg, nil
 }
 
-func dump(cfg *Config) {
-	data, err := json.MarshalIndent(cfg, "", "    ")
-	if err != nil {
-		log.Fatal("[FATAL] Cannot dump runtime config. ", err)
-	}
-	log.Println("[INFO] Runtime config\n" + string(data))
-}
-
 func parseMetrics(target, prefix, graphiteAddr string, interval time.Duration) []Metrics {
 	m := Metrics{Target: target, Prefix: prefix, Interval: interval}
 	if target == "graphite" {

main.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"flag"
 	"fmt"
 	"log"
 	"net"
@@ -32,23 +31,14 @@ import (
 var version = "1.1.1"
 
 func main() {
-	var filename string
-	var v bool
-	flag.StringVar(&filename, "cfg", "", "path to config file")
-	flag.BoolVar(&v, "v", false, "show version")
-	flag.Parse()
+	cfg, v := config.Load(os.Args[1:])
 
 	if v {
 		fmt.Println(version)
 		return
 	}
 	log.Printf("[INFO] Version %s starting", version)
 
-	cfg, err := config.Load(filename)
-	if err != nil {
-		log.Fatal("[FATAL] ", err)
-	}
-
 	initRuntime(cfg)
 	initMetrics(cfg)
 	initBackend(cfg)