From 7a6b7c9cdb10c290e18fb2204982bb5cdf57c5b2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thorben=20G=C3=BCnther?= <admin@xenrox.net>
Date: Wed, 8 Feb 2023 20:30:56 +0100
Subject: [PATCH] cache: Take alert status (firing, resolved) into account

Otherwise a resolved alert would not trigger a notification, since its
fingerprint - which is a generated hash from the labels - remains the
same.
---
 cache.go | 15 +++++++++++----
 main.go  |  4 ++--
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/cache.go b/cache.go
index 17bead6..1bbef10 100644
--- a/cache.go
+++ b/cache.go
@@ -6,9 +6,11 @@ import (
 )
 
 type fingerprint string
+type status string
 
 type cachedAlert struct {
 	expires time.Time
+	status  status
 }
 
 type cache struct {
@@ -39,18 +41,23 @@ func (c *cache) cleanup() {
 	}
 }
 
-func (c *cache) set(f fingerprint) {
+func (c *cache) set(f fingerprint, s status) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 	alert := new(cachedAlert)
 	alert.expires = time.Now().Add(c.duration)
+	alert.status = s
 
 	c.alerts[f] = alert
 }
 
-func (c *cache) contains(f fingerprint) bool {
+func (c *cache) contains(f fingerprint, s status) bool {
 	c.mu.Lock()
 	defer c.mu.Unlock()
-	_, ok := c.alerts[f]
-	return ok
+	alert, ok := c.alerts[f]
+	if ok {
+		return alert.status == s
+	}
+
+	return false
 }
diff --git a/main.go b/main.go
index 0a19912..7790c62 100644
--- a/main.go
+++ b/main.go
@@ -54,11 +54,11 @@ type notification struct {
 func (rcv *receiver) singleAlertNotifications(p *payload) []*notification {
 	var notifications []*notification
 	for _, alert := range p.Alerts {
-		if rcv.cache.contains(alert.Fingerprint) {
+		if rcv.cache.contains(alert.Fingerprint, status(alert.Status)) {
 			rcv.logger.Debugf("Alert %s skipped: Still in cache", alert.Fingerprint)
 			continue
 		}
-		rcv.cache.set(alert.Fingerprint)
+		rcv.cache.set(alert.Fingerprint, status(alert.Status))
 
 		n := new(notification)