Add ability to set bind address via command-line flag (#186)

config/loader_flags.go

@@ -5,7 +5,7 @@ package config
 func LoadConfigFromFlags(config *Config, flags *StartupFlags) error {
 	config.Listen = ListenConfig{
 		Port:            flags.ListenPort,
-		Address:         "0.0.0.0",
+		Address:         flags.ListenAddress,
 		MetricsEndpoint: flags.MetricsEndpoint,
 	}
 	config.Namespaces = []NamespaceConfig{

config/structs.go

@@ -8,6 +8,7 @@ type StartupFlags struct {
 	Parser                     string
 	Format                     string
 	Namespace                  string
+	ListenAddress              string
 	ListenPort                 int
 	EnableExperimentalFeatures bool
 	MetricsEndpoint            string

main.go

@@ -180,6 +180,7 @@ func main() {
 	nsGatherers := make(prometheus.Gatherers, 0)
 
 	flag.IntVar(&opts.ListenPort, "listen-port", 4040, "HTTP port to listen on")
+	flag.StringVar(&opts.ListenAddress, "listen-address", "0.0.0.0", "IP-address to bind")
 	flag.StringVar(&opts.Parser, "parser", "text", "NGINX access log format parser. One of: [text, json]")
 	flag.StringVar(&opts.Format, "format", `$remote_addr - $remote_user [$time_local] "$request" $status $body_bytes_sent "$http_referer" "$http_user_agent" "$http_x_forwarded_for"`, "NGINX access log format")
 	flag.StringVar(&opts.Namespace, "namespace", "nginx", "namespace to use for metric names")