From 41686c789873d94762371433fa7435d27a5de65d Mon Sep 17 00:00:00 2001
From: Viktor Polishchuk <viktorpo@wix.com>
Date: Tue, 19 Jun 2018 18:18:07 +0300
Subject: [PATCH] Added functionality to alter Webhook message

---
 config/notifiers.go |  3 +++
 notify/impl.go      | 21 +++++++++++++++++----
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/config/notifiers.go b/config/notifiers.go
index f7f627c879..52206bf7db 100644
--- a/config/notifiers.go
+++ b/config/notifiers.go
@@ -344,6 +344,9 @@ type WebhookConfig struct {
 
 	// URL to send POST request to.
 	URL string `yaml:"url" json:"url"`
+
+	// JSON message which will be sent instead of serialized data object
+    Message string `yaml:"message,omitempty" json:"message,omitempty"`
 }
 
 // UnmarshalYAML implements the yaml.Unmarshaler interface.
diff --git a/notify/impl.go b/notify/impl.go
index 8f3b555d2c..f069ac0358 100644
--- a/notify/impl.go
+++ b/notify/impl.go
@@ -147,7 +147,11 @@ type WebhookMessage struct {
 
 // Notify implements the Notifier interface.
 func (w *Webhook) Notify(ctx context.Context, alerts ...*types.Alert) (bool, error) {
-	data := w.tmpl.Data(receiverName(ctx, w.logger), groupLabels(ctx, w.logger), alerts...)
+	var err error
+    var (
+        data = w.tmpl.Data(receiverName(ctx, w.logger), groupLabels(ctx, w.logger), alerts...)
+        tmplText = tmplText(w.tmpl, data, &err)
+    )
 
 	groupKey, ok := GroupKey(ctx)
 	if !ok {
@@ -161,9 +165,18 @@ func (w *Webhook) Notify(ctx context.Context, alerts ...*types.Alert) (bool, err
 	}
 
 	var buf bytes.Buffer
-	if err := json.NewEncoder(&buf).Encode(msg); err != nil {
-		return false, err
-	}
+    
+    if messageText := tmplText(w.conf.Message); messageText != "" {
+        _, err := buf.WriteString(messageText)
+        
+        if err != nil {
+            return false, err
+        }
+    } else {
+        if err := json.NewEncoder(&buf).Encode(msg); err != nil {
+            return false, err
+        }
+    }
 
 	req, err := http.NewRequest("POST", w.conf.URL, &buf)
 	if err != nil {