Fix a bunch of unhandled errors (#1501)

...as discovered by "gosec" (many other ones reported, but not all make
a lot of sense to fix).

Signed-off-by: Julius Volz <julius.volz@gmail.com>

api/api.go

@@ -59,8 +59,8 @@ func init() {
 	numReceivedAlerts.WithLabelValues("firing")
 	numReceivedAlerts.WithLabelValues("resolved")
 
-	prometheus.Register(numReceivedAlerts)
-	prometheus.Register(numInvalidAlerts)
+	prometheus.MustRegister(numReceivedAlerts)
+	prometheus.MustRegister(numInvalidAlerts)
 }
 
 var corsHeaders = map[string]string{

cli/check_config.go

@@ -49,7 +49,10 @@ func (c *checkConfigCmd) checkConfig(ctx *kingpin.ParseContext) error {
 
 func CheckConfig(args []string) error {
 	if len(args) == 0 {
-		stat, _ := os.Stdin.Stat()
+		stat, err := os.Stdin.Stat()
+		if err != nil {
+			kingpin.Fatalf("Failed to stat standard input: %v", err)
+		}
 		if (stat.Mode() & os.ModeCharDevice) != 0 {
 			kingpin.Fatalf("Failed to read from standard input")
 		}

cli/format/format_extended.go

@@ -54,8 +54,7 @@ func (formatter *ExtendedFormatter) FormatSilences(silences []types.Silence) err
 			silence.Comment,
 		)
 	}
-	w.Flush()
-	return nil
+	return w.Flush()
 }
 
 func (formatter *ExtendedFormatter) FormatAlerts(alerts []*client.ExtendedAlert) error {
@@ -73,8 +72,7 @@ func (formatter *ExtendedFormatter) FormatAlerts(alerts []*client.ExtendedAlert)
 			alert.GeneratorURL,
 		)
 	}
-	w.Flush()
-	return nil
+	return w.Flush()
 }
 
 func (formatter *ExtendedFormatter) FormatConfig(status *client.ServerStatus) error {

cli/format/format_simple.go

@@ -52,8 +52,7 @@ func (formatter *SimpleFormatter) FormatSilences(silences []types.Silence) error
 			silence.Comment,
 		)
 	}
-	w.Flush()
-	return nil
+	return w.Flush()
 }
 
 func (formatter *SimpleFormatter) FormatAlerts(alerts []*client.ExtendedAlert) error {
@@ -69,8 +68,7 @@ func (formatter *SimpleFormatter) FormatAlerts(alerts []*client.ExtendedAlert) e
 			alert.Annotations["summary"],
 		)
 	}
-	w.Flush()
-	return nil
+	return w.Flush()
 }
 
 func (formatter *SimpleFormatter) FormatConfig(status *client.ServerStatus) error {

cli/silence_query.go

@@ -148,7 +148,9 @@ func (c *silenceQueryCmd) query(ctx context.Context, _ *kingpin.ParseContext) er
 		if !found {
 			return errors.New("unknown output formatter")
 		}
-		formatter.FormatSilences(displaySilences)
+		if err := formatter.FormatSilences(displaySilences); err != nil {
+			return fmt.Errorf("error formatting silences: %v", err)
+		}
 	}
 	return nil
 }

cli/silence_update.go

@@ -118,7 +118,9 @@ func (c *silenceUpdateCmd) update(ctx context.Context, _ *kingpin.ParseContext)
 		if !found {
 			return fmt.Errorf("unknown output formatter")
 		}
-		formatter.FormatSilences(updatedSilences)
+		if err := formatter.FormatSilences(updatedSilences); err != nil {
+			return fmt.Errorf("error formatting silences: %v", err)
+		}
 	}
 	return nil
 }

client/client.go

@@ -138,7 +138,10 @@ type httpStatusAPI struct {
 func (h *httpStatusAPI) Get(ctx context.Context) (*ServerStatus, error) {
 	u := h.client.URL(epStatus, nil)
 
-	req, _ := http.NewRequest(http.MethodGet, u.String(), nil)
+	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
+	if err != nil {
+		return nil, fmt.Errorf("error creating request: %v", err)
+	}
 
 	_, body, err := h.client.Do(ctx, req)
 	if err != nil {
@@ -207,7 +210,10 @@ func (h *httpAlertAPI) List(ctx context.Context, filter, receiver string, silenc
 	params.Add("receiver", receiver)
 	u.RawQuery = params.Encode()
 
-	req, _ := http.NewRequest(http.MethodGet, u.String(), nil)
+	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
+	if err != nil {
+		return nil, fmt.Errorf("error creating request: %v", err)
+	}
 
 	_, body, err := h.client.Do(ctx, req)
 	if err != nil {
@@ -228,9 +234,12 @@ func (h *httpAlertAPI) Push(ctx context.Context, alerts ...Alert) error {
 		return err
 	}
 
-	req, _ := http.NewRequest(http.MethodPost, u.String(), &buf)
+	req, err := http.NewRequest(http.MethodPost, u.String(), &buf)
+	if err != nil {
+		return fmt.Errorf("error creating request: %v", err)
+	}
 
-	_, _, err := h.client.Do(ctx, req)
+	_, _, err = h.client.Do(ctx, req)
 	return err
 }
 
@@ -260,7 +269,10 @@ func (h *httpSilenceAPI) Get(ctx context.Context, id string) (*types.Silence, er
 		"id": id,
 	})
 
-	req, _ := http.NewRequest(http.MethodGet, u.String(), nil)
+	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
+	if err != nil {
+		return nil, fmt.Errorf("error creating request: %v", err)
+	}
 
 	_, body, err := h.client.Do(ctx, req)
 	if err != nil {
@@ -278,9 +290,12 @@ func (h *httpSilenceAPI) Expire(ctx context.Context, id string) error {
 		"id": id,
 	})
 
-	req, _ := http.NewRequest(http.MethodDelete, u.String(), nil)
+	req, err := http.NewRequest(http.MethodDelete, u.String(), nil)
+	if err != nil {
+		return fmt.Errorf("error creating request: %v", err)
+	}
 
-	_, _, err := h.client.Do(ctx, req)
+	_, _, err = h.client.Do(ctx, req)
 	return err
 }
 
@@ -292,7 +307,10 @@ func (h *httpSilenceAPI) Set(ctx context.Context, sil types.Silence) (string, er
 		return "", err
 	}
 
-	req, _ := http.NewRequest(http.MethodPost, u.String(), &buf)
+	req, err := http.NewRequest(http.MethodPost, u.String(), &buf)
+	if err != nil {
+		return "", fmt.Errorf("error creating request: %v", err)
+	}
 
 	_, body, err := h.client.Do(ctx, req)
 	if err != nil {
@@ -315,7 +333,10 @@ func (h *httpSilenceAPI) List(ctx context.Context, filter string) ([]*types.Sile
 	}
 	u.RawQuery = params.Encode()
 
-	req, _ := http.NewRequest(http.MethodGet, u.String(), nil)
+	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
+	if err != nil {
+		return nil, fmt.Errorf("error creating request: %v", err)
+	}
 
 	_, body, err := h.client.Do(ctx, req)
 	if err != nil {

cmd/alertmanager/main.go

@@ -267,7 +267,9 @@ func main() {
 		ctx, cancel := context.WithTimeout(context.Background(), *settleTimeout)
 		defer func() {
 			cancel()
-			peer.Leave(10 * time.Second)
+			if err := peer.Leave(10 * time.Second); err != nil {
+				level.Warn(logger).Log("msg", "unable to leave gossip mesh", "err", err)
+			}
 		}()
 		go peer.Settle(ctx, *gossipInterval*10)
 	}

examples/webhook/echo.go

@@ -22,7 +22,7 @@ import (
 )
 
 func main() {
-	http.ListenAndServe(":5001", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	log.Fatal(http.ListenAndServe(":5001", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		b, err := ioutil.ReadAll(r.Body)
 		if err != nil {
 			panic(err)
@@ -33,5 +33,5 @@ func main() {
 			panic(err)
 		}
 		log.Println(buf.String())
-	}))
+	})))
 }

inhibit/inhibit.go

@@ -116,7 +116,9 @@ func (ih *Inhibitor) Run() {
 		runCancel()
 	})
 
-	g.Run()
+	if err := g.Run(); err != nil {
+		level.Warn(ih.logger).Log("msg", "error running inhibitor", "err", err)
+	}
 }
 
 // Stop the Inhibitor's background processing.

notify/impl.go

@@ -989,7 +989,10 @@ func (n *Wechat) Notify(ctx context.Context, as ...*types.Alert) (bool, error) {
 	}
 	defer resp.Body.Close()
 
-	body, _ := ioutil.ReadAll(resp.Body)
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return true, err
+	}
 	level.Debug(n.logger).Log("msg", "response: "+string(body), "incident", key)
 
 	if resp.StatusCode != 200 {

notify/notify.go

@@ -86,9 +86,9 @@ func init() {
 	notificationLatencySeconds.WithLabelValues("webhook")
 	notificationLatencySeconds.WithLabelValues("victorops")
 
-	prometheus.Register(numNotifications)
-	prometheus.Register(numFailedNotifications)
-	prometheus.Register(notificationLatencySeconds)
+	prometheus.MustRegister(numNotifications)
+	prometheus.MustRegister(numFailedNotifications)
+	prometheus.MustRegister(notificationLatencySeconds)
 }
 
 type notifierConfig interface {

test/acceptance.go

@@ -301,16 +301,22 @@ func (am *Alertmanager) Start() {
 // Terminate kills the underlying Alertmanager process and remove intermediate
 // data.
 func (am *Alertmanager) Terminate() {
-	syscall.Kill(am.cmd.Process.Pid, syscall.SIGTERM)
+	if err := syscall.Kill(am.cmd.Process.Pid, syscall.SIGTERM); err != nil {
+		am.t.Fatalf("Error sending SIGTERM to Alertmanager process: %v", err)
+	}
 }
 
 // Reload sends the reloading signal to the Alertmanager process.
 func (am *Alertmanager) Reload() {
-	syscall.Kill(am.cmd.Process.Pid, syscall.SIGHUP)
+	if err := syscall.Kill(am.cmd.Process.Pid, syscall.SIGHUP); err != nil {
+		am.t.Fatalf("Error sending SIGHUP to Alertmanager process: %v", err)
+	}
 }
 
 func (am *Alertmanager) cleanup() {
-	os.RemoveAll(am.confFile.Name())
+	if err := os.RemoveAll(am.confFile.Name()); err != nil {
+		am.t.Errorf("Error removing test config file %q: %v", am.confFile.Name(), err)
+	}
 }
 
 // Push declares alerts that are to be pushed to the Alertmanager