From 9043ccfb5efd487996b3666888f922507259a181 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thorben=20G=C3=BCnther?= <admin@xenrox.net>
Date: Wed, 12 Oct 2022 16:35:04 +0200
Subject: [PATCH] Set ntfy priority depending on Prometheus labels

It is possible to configure a priority for an arbitrary label.
Furthermore a priority/order of those arbitrary labels should be
defined. The Alertmanager payload is checked for these and the
priority will be selected from the highest valued label that has one
set in the configuration file.
---
 config.go | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 main.go   | 22 ++++++++++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/config.go b/config.go
index 3108a24..10a405f 100644
--- a/config.go
+++ b/config.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"strings"
 
 	"git.sr.ht/~emersion/go-scfg"
 )
@@ -12,6 +13,7 @@ type config struct {
 	User        string
 	Password    string
 	ntfy        ntfyConfig
+	labels      labels
 }
 
 type ntfyConfig struct {
@@ -20,6 +22,15 @@ type ntfyConfig struct {
 	Password string
 }
 
+type labels struct {
+	Order []string
+	Label map[string]labelConfig
+}
+
+type labelConfig struct {
+	Priority string
+}
+
 func readConfig(path string) (*config, error) {
 	cfg, err := scfg.Load(path)
 	if err != nil {
@@ -59,6 +70,44 @@ func readConfig(path string) (*config, error) {
 		}
 	}
 
+	labelsDir := cfg.Get("labels")
+	if labelsDir != nil {
+		d = labelsDir.Children.Get("order")
+		if d != nil {
+			var order string
+			if err := d.ParseParams(&order); err != nil {
+				return nil, err
+			}
+
+			config.labels.Order = strings.Split(order, ",")
+		}
+
+		labels := make(map[string]labelConfig)
+		for _, labelName := range config.labels.Order {
+			labelDir := labelsDir.Children.Get(labelName)
+
+			if labelDir != nil {
+				labelConfig := new(labelConfig)
+				var name string
+
+				if err := labelDir.ParseParams(&name); err != nil {
+					return nil, err
+				}
+
+				d = labelDir.Children.Get("priority")
+				if d != nil {
+					if err := d.ParseParams(&labelConfig.Priority); err != nil {
+						return nil, err
+					}
+				}
+
+				labels[fmt.Sprintf("%s:%s", labelName, name)] = *labelConfig
+			}
+		}
+
+		config.labels.Label = labels
+	}
+
 	ntfyDir := cfg.Get("ntfy")
 	if ntfyDir == nil {
 		return nil, fmt.Errorf("%q directive missing", "ntfy")
diff --git a/main.go b/main.go
index 36a2b33..c15dcf0 100644
--- a/main.go
+++ b/main.go
@@ -98,6 +98,28 @@ func (rcv *receiver) handleWebhooks(w http.ResponseWriter, r *http.Request) {
 	}
 
 	req.Header.Set("X-Title", title)
+
+	var priority string
+	for _, labelName := range rcv.cfg.labels.Order {
+		val, ok := event.CommonLabels[labelName]
+		if !ok {
+			continue
+		}
+
+		labelConfig, ok := rcv.cfg.labels.Label[fmt.Sprintf("%s:%s", labelName, val)]
+		if !ok {
+			continue
+		}
+
+		if priority == "" {
+			priority = labelConfig.Priority
+		}
+	}
+
+	if priority != "" {
+		req.Header.Set("X-Priority", priority)
+	}
+
 	resp, err := client.Do(req)
 	if err != nil {
 		rcv.logger.Error(err)