Alerting: Update Discord receiver to use encoding/json to build a webhook message + truncate long message (#60592)

* replace simplejson with models * truncate too long messages Co-authored-by: Santiago <santiagohernandez.1997@gmail.com>
2 years ago · 4a3097f52a
parent aaa55b4252
commit 4a3097f52a
2 changed files with 104 additions and 26 deletions
--- a/pkg/services/ngalert/notifier/channels/discord.go
+++ b/pkg/services/ngalert/notifier/channels/discord.go
@ -13,13 +13,53 @@ import (
 	"strings"

 	"github.com/grafana/alerting/alerting/notifier/channels"
+	"github.com/prometheus/alertmanager/notify"
 	"github.com/prometheus/alertmanager/template"
 	"github.com/prometheus/alertmanager/types"
 	"github.com/prometheus/common/model"
+)
+
+// Constants and models are set according to the official documentation https://discord.com/developers/docs/resources/webhook#execute-webhook-jsonform-params
+
+type discordEmbedType string

-	"github.com/grafana/grafana/pkg/components/simplejson"
+const (
+	discordRichEmbed discordEmbedType = "rich"
+
+	discordMaxEmbeds     = 10
+	discordMaxMessageLen = 2000
 )

+type discordMessage struct {
+	Username  string             `json:"username,omitempty"`
+	Content   string             `json:"content"`
+	AvatarURL string             `json:"avatar_url,omitempty"`
+	Embeds    []discordLinkEmbed `json:"embeds,omitempty"`
+}
+
+// discordLinkEmbed implements https://discord.com/developers/docs/resources/channel#embed-object
+type discordLinkEmbed struct {
+	Title string           `json:"title,omitempty"`
+	Type  discordEmbedType `json:"type,omitempty"`
+	URL   string           `json:"url,omitempty"`
+	Color int64            `json:"color,omitempty"`
+
+	Footer *discordFooter `json:"footer,omitempty"`
+
+	Image *discordImage `json:"image,omitempty"`
+}
+
+// discordFooter implements https://discord.com/developers/docs/resources/channel#embed-object-embed-footer-structure
+type discordFooter struct {
+	Text    string `json:"text"`
+	IconURL string `json:"icon_url,omitempty"`
+}
+
+// discordImage implements https://discord.com/developers/docs/resources/channel#embed-object-embed-footer-structure
+type discordImage struct {
+	URL string `json:"url"`
+}
+
 type DiscordNotifier struct {
 	*channels.Base
 	log        channels.Logger
@ -64,8 +104,6 @@ type discordAttachment struct {
 	state     model.AlertStatus
 }

-const DiscordMaxEmbeds = 10
-
 func DiscordFactory(fc channels.FactoryConfig) (channels.NotificationChannel, error) {
 	dn, err := newDiscordNotifier(fc)
 	if err != nil {
@ -96,69 +134,78 @@ func newDiscordNotifier(fc channels.FactoryConfig) (*DiscordNotifier, error) {
 func (d DiscordNotifier) Notify(ctx context.Context, as ...*types.Alert) (bool, error) {
 	alerts := types.Alerts(as...)

-	bodyJSON := simplejson.New()
+	var msg discordMessage

 	if !d.settings.UseDiscordUsername {
-		bodyJSON.Set("username", "Grafana")
+		msg.Username = "Grafana"
 	}

 	var tmplErr error
 	tmpl, _ := channels.TmplText(ctx, d.tmpl, as, d.log, &tmplErr)

-	bodyJSON.Set("content", tmpl(d.settings.Message))
+	msg.Content = tmpl(d.settings.Message)
 	if tmplErr != nil {
 		d.log.Warn("failed to template Discord notification content", "error", tmplErr.Error())
 		// Reset tmplErr for templating other fields.
 		tmplErr = nil
 	}
+	truncatedMsg, truncated := channels.TruncateInRunes(msg.Content, discordMaxMessageLen)
+	if truncated {
+		key, err := notify.ExtractGroupKey(ctx)
+		if err != nil {
+			return false, err
+		}
+		d.log.Warn("Truncated content", "key", key, "max_runes", discordMaxMessageLen)
+		msg.Content = truncatedMsg
+	}

 	if d.settings.AvatarURL != "" {
-		bodyJSON.Set("avatar_url", tmpl(d.settings.AvatarURL))
+		msg.AvatarURL = tmpl(d.settings.AvatarURL)
 		if tmplErr != nil {
 			d.log.Warn("failed to template Discord Avatar URL", "error", tmplErr.Error(), "fallback", d.settings.AvatarURL)
-			bodyJSON.Set("avatar_url", d.settings.AvatarURL)
+			msg.AvatarURL = d.settings.AvatarURL
 			tmplErr = nil
 		}
 	}

-	footer := map[string]interface{}{
-		"text":     "Grafana v" + d.appVersion,
-		"icon_url": "https://grafana.com/static/assets/img/fav32.png",
+	footer := &discordFooter{
+		Text:    "Grafana v" + d.appVersion,
+		IconURL: "https://grafana.com/static/assets/img/fav32.png",
 	}

-	linkEmbed := simplejson.New()
+	var linkEmbed discordLinkEmbed

-	linkEmbed.Set("title", tmpl(d.settings.Title))
+	linkEmbed.Title = tmpl(d.settings.Title)
 	if tmplErr != nil {
 		d.log.Warn("failed to template Discord notification title", "error", tmplErr.Error())
 		// Reset tmplErr for templating other fields.
 		tmplErr = nil
 	}
-	linkEmbed.Set("footer", footer)
-	linkEmbed.Set("type", "rich")
+	linkEmbed.Footer = footer
+	linkEmbed.Type = discordRichEmbed

 	color, _ := strconv.ParseInt(strings.TrimLeft(getAlertStatusColor(alerts.Status()), "#"), 16, 0)
-	linkEmbed.Set("color", color)
+	linkEmbed.Color = color

 	ruleURL := joinUrlPath(d.tmpl.ExternalURL.String(), "/alerting/list", d.log)
-	linkEmbed.Set("url", ruleURL)
+	linkEmbed.URL = ruleURL

-	embeds := []interface{}{linkEmbed}
+	embeds := []discordLinkEmbed{linkEmbed}

-	attachments := d.constructAttachments(ctx, as, DiscordMaxEmbeds-1)
+	attachments := d.constructAttachments(ctx, as, discordMaxEmbeds-1)
 	for _, a := range attachments {
 		color, _ := strconv.ParseInt(strings.TrimLeft(getAlertStatusColor(alerts.Status()), "#"), 16, 0)
-		embed := map[string]interface{}{
-			"image": map[string]interface{}{
-				"url": a.url,
+		embed := discordLinkEmbed{
+			Image: &discordImage{
+				URL: a.url,
 			},
-			"color": color,
-			"title": a.alertName,
+			Color: color,
+			Title: a.alertName,
 		}
 		embeds = append(embeds, embed)
 	}

-	bodyJSON.Set("embeds", embeds)
+	msg.Embeds = embeds

 	if tmplErr != nil {
 		d.log.Warn("failed to template Discord message", "error", tmplErr.Error())
@ -171,7 +218,7 @@ func (d DiscordNotifier) Notify(ctx context.Context, as ...*types.Alert) (bool,
 		u = d.settings.WebhookURL
 	}

-	body, err := json.Marshal(bodyJSON)
+	body, err := json.Marshal(msg)
 	if err != nil {
 		return false, err
 	}
--- a/pkg/services/ngalert/notifier/channels/discord_test.go
+++ b/pkg/services/ngalert/notifier/channels/discord_test.go
@ -6,6 +6,7 @@ import (
 	"fmt"
 	"math/rand"
 	"net/url"
+	"strings"
 	"testing"

 	"github.com/grafana/alerting/alerting/notifier/channels"
@ -283,6 +284,36 @@ func TestDiscordNotifier(t *testing.T) {
 			},
 			expMsgError: nil,
 		},
+		{
+			name: "Should truncate too long messages",
+			settings: fmt.Sprintf(`{
+				"url": "http://localhost",
+				"use_discord_username": true,
+				"message": "%s"
+			}`, strings.Repeat("Y", discordMaxMessageLen+rand.Intn(100)+1)),
+			alerts: []*types.Alert{
+				{
+					Alert: model.Alert{
+						Labels:      model.LabelSet{"alertname": "alert1", "lbl1": "val1"},
+						Annotations: model.LabelSet{"ann1": "annv1", "__dashboardUid__": "abcd", "__panelId__": "efgh"},
+					},
+				},
+			},
+			expMsg: map[string]interface{}{
+				"content": strings.Repeat("Y", discordMaxMessageLen-1) + "…",
+				"embeds": []interface{}{map[string]interface{}{
+					"color": 1.4037554e+07,
+					"footer": map[string]interface{}{
+						"icon_url": "https://grafana.com/static/assets/img/fav32.png",
+						"text":     "Grafana v" + appVersion,
+					},
+					"title": "[FIRING:1]  (val1)",
+					"url":   "http://localhost/alerting/list",
+					"type":  "rich",
+				}},
+			},
+			expMsgError: nil,
+		},
 	}

 	for _, c := range cases {