From b0d6628f82ca5a4d742e91606eeb44b179ed5a2b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Mierzwa?= <l.mierzwa@gmail.com>
Date: Sun, 25 Jun 2017 11:07:28 -0700
Subject: [PATCH] Generate alert unique fingerprint on the fly

---
 alertmanager/dedup.go     |  7 ++++---
 alertmanager/models.go    | 10 +++-------
 models/alert.go           |  7 ++++++-
 models/alertgroup_test.go |  2 +-
 4 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/alertmanager/dedup.go b/alertmanager/dedup.go
index 9d36e8137..2f6646f57 100644
--- a/alertmanager/dedup.go
+++ b/alertmanager/dedup.go
@@ -27,14 +27,15 @@ func DedupAlerts() []models.AlertGroup {
 		alerts := map[string]models.Alert{}
 		for _, ag := range agList {
 			for _, alert := range ag.Alerts {
-				a, found := alerts[alert.ID]
+				alertLFP := alert.LabelsFingerprint()
+				a, found := alerts[alertLFP]
 				if found {
 					for _, am := range alert.Alertmanager {
 						a.Alertmanager = append(a.Alertmanager, am)
-						alerts[alert.ID] = a
+						alerts[alertLFP] = a
 					}
 				} else {
-					alerts[alert.ID] = alert
+					alerts[alertLFP] = alert
 				}
 			}
 		}
diff --git a/alertmanager/models.go b/alertmanager/models.go
index 8b5125f96..517a28e86 100644
--- a/alertmanager/models.go
+++ b/alertmanager/models.go
@@ -119,16 +119,12 @@ func (am *Alertmanager) pullAlerts(version string) error {
 			}
 		}
 		for _, alert := range ag.Alerts {
-			// generate alert id from labels
-			aID := fmt.Sprintf("%x", structhash.Sha1(alert.Labels, 1))
-			alert.ID = aID
-			// generate alert fingerprint from a raw, unaltered alert object
-			fp := fmt.Sprintf("%x", structhash.Sha1(alert, 1))
 			if _, found := uniqueAlerts[agID]; !found {
 				uniqueAlerts[agID] = map[string]models.Alert{}
 			}
-			if _, found := uniqueAlerts[agID][fp]; !found {
-				uniqueAlerts[agID][fp] = alert
+			alertCFP := alert.ContentFingerprint()
+			if _, found := uniqueAlerts[agID][alertCFP]; !found {
+				uniqueAlerts[agID][alertCFP] = alert
 			}
 		}
 
diff --git a/models/alert.go b/models/alert.go
index efdff33fb..7ba954efd 100644
--- a/models/alert.go
+++ b/models/alert.go
@@ -42,7 +42,12 @@ type Alert struct {
 	Alertmanager []AlertmanagerUpstream `json:"alertmanager"`
 	Receiver     string                 `json:"receiver"`
 	Links        map[string]string      `json:"links"`
-	ID           string                 `json:"-"`
+}
+
+// LabelsFingerprint is a checksum computed only from labels which should be
+// unique for every alert
+func (a Alert) LabelsFingerprint() string {
+	return fmt.Sprintf("%x", structhash.Sha1(a.Labels, 1))
 }
 
 // ContentFingerprint is a checksum computed from entire alert object
diff --git a/models/alertgroup_test.go b/models/alertgroup_test.go
index 1f7a4ca29..ab505417b 100644
--- a/models/alertgroup_test.go
+++ b/models/alertgroup_test.go
@@ -114,7 +114,7 @@ var agFPTests = []agFPTest{
 			},
 			StateCount: map[string]int{"default": 0},
 		},
-		fingerprint: "c4a76e2d59f7ef3d49b20da06c4a89f63fdf9e3f",
+		fingerprint: "954a7283c2cda4179b63499465d82a313d21180f",
 	},
 }