notify: factorize code truncating strings (#1752)

Signed-off-by: Simon Pasquier <spasquie@redhat.com>

notify/impl.go

@@ -1221,10 +1221,9 @@ func (n *OpsGenie) createRequest(ctx context.Context, as ...*types.Alert) (*http
 		apiURL.RawQuery = q.Encode()
 		msg = &opsGenieCloseMessage{Source: tmpl(n.conf.Source)}
 	default:
-		message := tmpl(n.conf.Message)
+		message, truncated := truncate(tmpl(n.conf.Message), 130)
-		if len(message) > 130 {
+		if truncated {
-			message = message[:127] + "..."
+			level.Debug(n.logger).Log("msg", "truncated message due to OpsGenie message limit", "truncated_message", message, "incident", key)
-			level.Debug(n.logger).Log("msg", "Truncated message to %q due to OpsGenie message limit", "truncated_message", message, "incident", key)
 		}
 
 		apiURL.Path += "v2/alerts"
@@ -1362,9 +1361,9 @@ func (n *VictorOps) createVictorOpsPayload(ctx context.Context, as ...*types.Ale
 		messageType = victorOpsEventResolve
 	}
 
-	if len(stateMessage) > 20480 {
+	stateMessage, truncated := truncate(stateMessage, 20480)
-		stateMessage = stateMessage[0:20475] + "\n..."
+	if truncated {
-		level.Debug(n.logger).Log("msg", "Truncated stateMessage due to VictorOps stateMessage limit", "truncated_state_message", stateMessage, "incident", key)
+		level.Debug(n.logger).Log("msg", "truncated stateMessage due to VictorOps stateMessage limit", "truncated_state_message", stateMessage, "incident", key)
 	}
 
 	msg := map[string]string{
@@ -1439,9 +1438,8 @@ func (n *Pushover) Notify(ctx context.Context, as ...*types.Alert) (bool, error)
 	parameters.Add("token", tmpl(string(n.conf.Token)))
 	parameters.Add("user", tmpl(string(n.conf.UserKey)))
 
-	title := tmpl(n.conf.Title)
+	title, truncated := truncate(tmpl(n.conf.Title), 250)
-	if len(title) > 250 {
+	if truncated {
-		title = title[:247] + "..."
 		level.Debug(n.logger).Log("msg", "Truncated title due to Pushover title limit", "truncated_title", title, "incident", key)
 	}
 	parameters.Add("title", title)
@@ -1453,8 +1451,8 @@ func (n *Pushover) Notify(ctx context.Context, as ...*types.Alert) (bool, error)
 		message = tmpl(n.conf.Message)
 	}
 
-	if len(message) > 1024 {
+	message, truncated = truncate(message, 1024)
-		message = message[:1021] + "..."
+	if truncated {
 		level.Debug(n.logger).Log("msg", "Truncated message due to Pushover message limit", "truncated_message", message, "incident", key)
 	}
 	message = strings.TrimSpace(message)
@@ -1464,9 +1462,8 @@ func (n *Pushover) Notify(ctx context.Context, as ...*types.Alert) (bool, error)
 	}
 	parameters.Add("message", message)
 
-	supplementaryURL := tmpl(n.conf.URL)
+	supplementaryURL, truncated := truncate(tmpl(n.conf.URL), 512)
-	if len(supplementaryURL) > 512 {
+	if truncated {
-		supplementaryURL = supplementaryURL[:509] + "..."
 		level.Debug(n.logger).Log("msg", "Truncated URL due to Pushover url limit", "truncated_url", supplementaryURL, "incident", key)
 	}
 	parameters.Add("url", supplementaryURL)
@@ -1582,3 +1579,14 @@ func post(ctx context.Context, client *http.Client, url string, bodyType string,
 	req.Header.Set("Content-Type", bodyType)
 	return client.Do(req.WithContext(ctx))
 }
+
+func truncate(s string, n int) (string, bool) {
+	r := []rune(s)
+	if len(r) <= n {
+		return s, false
+	}
+	if n <= 3 {
+		return string(r[:n]), true
+	}
+	return string(r[:n-3]) + "...", true
+}

notify/impl_test.go

@@ -371,3 +371,64 @@ func TestVictorOpsCustomFields(t *testing.T) {
 	// Verify that a custom field was added to the payload and templatized.
 	require.Equal(t, "message", m["Field_A"])
 }
+
+func TestTruncate(t *testing.T) {
+	testCases := []struct {
+		in string
+		n  int
+
+		out   string
+		trunc bool
+	}{
+		{
+			in:    "",
+			n:     5,
+			out:   "",
+			trunc: false,
+		},
+		{
+			in:    "abcde",
+			n:     2,
+			out:   "ab",
+			trunc: true,
+		},
+		{
+			in:    "abcde",
+			n:     4,
+			out:   "a...",
+			trunc: true,
+		},
+		{
+			in:    "abcde",
+			n:     5,
+			out:   "abcde",
+			trunc: false,
+		},
+		{
+			in:    "abcdefgh",
+			n:     5,
+			out:   "ab...",
+			trunc: true,
+		},
+		{
+			in:    "a⌘cde",
+			n:     5,
+			out:   "a⌘cde",
+			trunc: false,
+		},
+		{
+			in:    "a⌘cdef",
+			n:     5,
+			out:   "a⌘...",
+			trunc: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(fmt.Sprintf("truncate(%s,%d)", tc.in, tc.n), func(t *testing.T) {
+			s, trunc := truncate(tc.in, tc.n)
+			require.Equal(t, tc.trunc, trunc)
+			require.Equal(t, tc.out, s)
+		})
+	}
+}