adding support for token-based slack file.upload API call for posting images to slack

pkg/services/alerting/notifiers/slack.go

@@ -1,7 +1,11 @@
 package notifiers
 
 import (
+	"bytes"
 	"encoding/json"
+	"io"
+	"mime/multipart"
+	"os"
 	"time"
 
 	"github.com/grafana/grafana/pkg/bus"
@@ -15,7 +19,7 @@ func init() {
 	alerting.RegisterNotifier(&alerting.NotifierPlugin{
 		Type:        "slack",
 		Name:        "Slack",
-		Description: "Sends notifications using Grafana server configured STMP settings",
+		Description: "Sends notifications to Slack via Slack Webhooks",
 		Factory:     NewSlackNotifier,
 		OptionsTemplate: `
       <h3 class="page-heading">Slack settings</h3>
@@ -45,6 +49,17 @@ func init() {
           Mention a user or a group using @ when notifying in a channel
         </info-popover>
       </div>
+      <div class="gf-form max-width-30">
+        <span class="gf-form-label width-6">Token</span>
+        <input type="text"
+          class="gf-form-input max-width-30"
+          ng-model="ctrl.model.settings.token"
+          data-placement="right">
+        </input>
+        <info-popover mode="right-absolute">
+          Provide a bot token to use the Slack file.upload API (starts with "xoxb")
+        </info-popover>
+      </div>
     `,
 	})
 
@@ -58,12 +73,14 @@ func NewSlackNotifier(model *m.AlertNotification) (alerting.Notifier, error) {
 
 	recipient := model.Settings.Get("recipient").MustString()
 	mention := model.Settings.Get("mention").MustString()
+	token := model.Settings.Get("token").MustString()
 
 	return &SlackNotifier{
 		NotifierBase: NewNotifierBase(model.Id, model.IsDefault, model.Name, model.Type, model.Settings),
 		Url:          url,
 		Recipient:    recipient,
 		Mention:      mention,
+		Token:        token,
 		log:          log.New("alerting.notifier.slack"),
 	}, nil
 }
@@ -73,6 +90,7 @@ type SlackNotifier struct {
 	Url       string
 	Recipient string
 	Mention   string
+	Token     string
 	log       log.Logger
 }
 
@@ -110,6 +128,11 @@ func (this *SlackNotifier) Notify(evalContext *alerting.EvalContext) error {
 	if evalContext.Rule.State != m.AlertStateOK { //dont add message when going back to alert state ok.
 		message += " " + evalContext.Rule.Message
 	}
+	image_url := ""
+	// default to file.upload API method if a token is provided
+	if this.Token == "" {
+		image_url = evalContext.ImagePublicUrl
+	}
 
 	body := map[string]interface{}{
 		"attachments": []map[string]interface{}{
@@ -120,7 +143,7 @@ func (this *SlackNotifier) Notify(evalContext *alerting.EvalContext) error {
 				"title_link":  ruleUrl,
 				"text":        message,
 				"fields":      fields,
-				"image_url":   evalContext.ImagePublicUrl,
+				"image_url":   image_url,
 				"footer":      "Grafana v" + setting.BuildVersion,
 				"footer_icon": "https://grafana.com/assets/img/fav32.png",
 				"ts":          time.Now().Unix(),
@@ -133,14 +156,69 @@ func (this *SlackNotifier) Notify(evalContext *alerting.EvalContext) error {
 	if this.Recipient != "" {
 		body["channel"] = this.Recipient
 	}
-
 	data, _ := json.Marshal(&body)
 	cmd := &m.SendWebhookSync{Url: this.Url, Body: string(data)}
-
 	if err := bus.DispatchCtx(evalContext.Ctx, cmd); err != nil {
 		this.log.Error("Failed to send slack notification", "error", err, "webhook", this.Name)
 		return err
 	}
+	if this.Token != "" {
+		slackUploadUrl := "https://slack.com/api/files.upload"
+		if evalContext.ImageOnDiskPath == "" {
+			evalContext.ImageOnDiskPath = "public/img/mixed_styles.png"
+		}
+		this.log.Info("Uploading to slack via file.upload API")
+		headers, uploadBody, err := GenerateSlackUpload(evalContext.ImageOnDiskPath, this.Token, this.Recipient)
+		if err != nil {
+			return err
+		}
+		cmd := &m.SendWebhookSync{Url: slackUploadUrl, Body: uploadBody.String(), HttpHeader: headers, HttpMethod: "POST"}
+		if err := bus.DispatchCtx(evalContext.Ctx, cmd); err != nil {
+			this.log.Error("Failed to upload slack image", "error", err, "webhook", "file.upload")
+			return err
+		}
+		if err != nil {
+			return err
+		}
+	}
 
 	return nil
 }
+
+func GenerateSlackUpload(file string, token string, recipient string) (map[string]string, bytes.Buffer, error) {
+	// Slack requires all POSTs to files.upload to present
+	// an "application/x-www-form-urlencoded" encoded querystring
+	// See https://api.slack.com/methods/files.upload
+	var b bytes.Buffer
+	w := multipart.NewWriter(&b)
+	// Add the generated image file
+	f, err := os.Open(file)
+	if err != nil {
+		return nil, b, err
+	}
+	defer f.Close()
+	fw, err := w.CreateFormFile("file", file)
+	if err != nil {
+		return nil, b, err
+	}
+	_, err = io.Copy(fw, f)
+	if err != nil {
+		return nil, b, err
+	}
+	// Add the authorization token
+	err = w.WriteField("token", token)
+	if err != nil {
+		return nil, b, err
+	}
+	// Add the channel(s) to POST to
+	err = w.WriteField("channels", recipient)
+	if err != nil {
+		return nil, b, err
+	}
+	w.Close()
+	headers := map[string]string{
+		"Content-Type":  w.FormDataContentType(),
+		"Authorization": "auth_token=\"" + token + "\"",
+	}
+	return headers, b, nil
+}

pkg/services/alerting/notifiers/slack_test.go

@@ -48,6 +48,7 @@ func TestSlackNotifier(t *testing.T) {
 				So(slackNotifier.Url, ShouldEqual, "http://google.com")
 				So(slackNotifier.Recipient, ShouldEqual, "")
 				So(slackNotifier.Mention, ShouldEqual, "")
+				So(slackNotifier.Token, ShouldEqual, "")
 			})
 
 			Convey("from settings with Recipient and Mention", func() {
@@ -56,6 +57,7 @@ func TestSlackNotifier(t *testing.T) {
           "url": "http://google.com",
           "recipient": "#ds-opentsdb",
           "mention": "@carl"
+          "token": "xoxb-XXXXXXXX-XXXXXXXX-XXXXXXXXXX",
 				}`
 
 				settingsJSON, _ := simplejson.NewJson([]byte(json))
@@ -74,6 +76,7 @@ func TestSlackNotifier(t *testing.T) {
 				So(slackNotifier.Url, ShouldEqual, "http://google.com")
 				So(slackNotifier.Recipient, ShouldEqual, "#ds-opentsdb")
 				So(slackNotifier.Mention, ShouldEqual, "@carl")
+				So(slackNotifier.Token, ShouldEqual, "xoxb-XXXXXXXX-XXXXXXXX-XXXXXXXXXX")
 			})
 
 		})