improve startup-log

When given only a port (i.e. --web.listen-address=:9836, the
default), the startup message read "Starting on http://:9836/".
This is now changed to "Starting on http://0.0.0.0:9836/",
which allows to click on the URL in the terminal (if the
terminal supports this).

Author: dmke

exporter/config.go

@@ -63,7 +63,7 @@ func LoadClientConfig(file string, verbose bool) (*Client, error) {
 }
 
 func (c *Client) login() error {
-	c.log.Debugf("performing login")
+	c.log.Infof("performing login")
 	ctx, cancel := context.WithTimeout(context.Background(), loginTimeout)
 	defer cancel()
 

exporter/exporter.go

@@ -2,8 +2,10 @@ package exporter
 
 import (
 	"encoding/json"
+	"fmt"
 	"html/template"
 	"log"
+	"net"
 	"net/http"
 
 	"github.com/julienschmidt/httprouter"
@@ -39,7 +41,14 @@ func (c *Client) Start(listenAddress, version string) error {
 	router.GET("/apgroups/:ap_group/debug", c.debugHandler)
 	router.GET("/apgroups/:ap_group/metrics", c.metricsHandler)
 
-	log.Printf("Starting exporter on http://%s/", listenAddress)
+	var where string
+	if host, port, err := net.SplitHostPort(listenAddress); err == nil && host == "" {
+		where = fmt.Sprintf("http://0.0.0.0:%s/", port)
+	} else {
+		where = fmt.Sprintf("http://%s/", listenAddress)
+	}
+
+	c.log.Infof("Starting exporter on %s", where)
 
 	return http.ListenAndServe(listenAddress, router)
 }