From 8c3a5f6da0aa52ffc1d680f0cb7c2a7884d29d45 Mon Sep 17 00:00:00 2001
From: Alexander Weaver <weaver.alex.d@gmail.com>
Date: Thu, 5 Jan 2023 12:21:07 -0600
Subject: [PATCH] Alerting: Allow state history to be disabled through
 configuration (#61006)

* Add configuration option for if state history should be enabled

* Inject no-op when history is disabled
---
 conf/defaults.ini                            |  4 ++++
 pkg/services/ngalert/ngalert.go              |  9 +++++++--
 pkg/services/ngalert/state/historian/noop.go | 18 ++++++++++++++++++
 pkg/setting/setting_unified_alerting.go      | 12 ++++++++++++
 4 files changed, 41 insertions(+), 2 deletions(-)
 create mode 100644 pkg/services/ngalert/state/historian/noop.go

diff --git a/conf/defaults.ini b/conf/defaults.ini
index 94e864591cc..922cb5985aa 100644
--- a/conf/defaults.ini
+++ b/conf/defaults.ini
@@ -964,6 +964,10 @@ upload_external_image_storage = false
 # For example: `disabled_labels=grafana_folder`
 disabled_labels =
 
+[unified_alerting.state_history]
+# Enable the state history functionality in Unified Alerting. The previous states of alert rules will be visible in panels and in the UI.
+enabled = true
+
 #################################### Alerting ############################
 [alerting]
 # Enable the legacy alerting sub-system and interface. If Unified Alerting is already enabled and you try to go back to legacy alerting, all data that is part of Unified Alerting will be deleted. When this configuration section and flag are not defined, the state is defined at runtime. See the documentation for more details.
diff --git a/pkg/services/ngalert/ngalert.go b/pkg/services/ngalert/ngalert.go
index b3f6f783afc..bdad7dd76ce 100644
--- a/pkg/services/ngalert/ngalert.go
+++ b/pkg/services/ngalert/ngalert.go
@@ -200,8 +200,13 @@ func (ng *AlertNG) init() error {
 		AlertSender:          alertsRouter,
 	}
 
-	historian := historian.NewAnnotationHistorian(ng.annotationsRepo, ng.dashboardService)
-	stateManager := state.NewManager(ng.Metrics.GetStateMetrics(), appUrl, store, ng.imageService, clk, historian)
+	var history state.Historian
+	if ng.Cfg.UnifiedAlerting.StateHistory.Enabled {
+		history = historian.NewAnnotationHistorian(ng.annotationsRepo, ng.dashboardService)
+	} else {
+		history = historian.NewNopHistorian()
+	}
+	stateManager := state.NewManager(ng.Metrics.GetStateMetrics(), appUrl, store, ng.imageService, clk, history)
 	scheduler := schedule.NewScheduler(schedCfg, stateManager)
 
 	// if it is required to include folder title to the alerts, we need to subscribe to changes of alert title
diff --git a/pkg/services/ngalert/state/historian/noop.go b/pkg/services/ngalert/state/historian/noop.go
new file mode 100644
index 00000000000..76c40643772
--- /dev/null
+++ b/pkg/services/ngalert/state/historian/noop.go
@@ -0,0 +1,18 @@
+package historian
+
+import (
+	"context"
+
+	"github.com/grafana/grafana/pkg/services/ngalert/models"
+	"github.com/grafana/grafana/pkg/services/ngalert/state"
+)
+
+// NoOpHistorian is a state.Historian that does nothing with the resulting data, to be used in contexts where history is not needed.
+type NoOpHistorian struct{}
+
+func NewNopHistorian() *NoOpHistorian {
+	return &NoOpHistorian{}
+}
+
+func (f *NoOpHistorian) RecordStatesAsync(ctx context.Context, _ *models.AlertRule, _ []state.StateTransition) {
+}
diff --git a/pkg/setting/setting_unified_alerting.go b/pkg/setting/setting_unified_alerting.go
index f2c9725ea17..b134e1810d9 100644
--- a/pkg/setting/setting_unified_alerting.go
+++ b/pkg/setting/setting_unified_alerting.go
@@ -60,6 +60,7 @@ const (
 	SchedulerBaseInterval = 10 * time.Second
 	// DefaultRuleEvaluationInterval indicates a default interval of for how long a rule should be evaluated to change state from Pending to Alerting
 	DefaultRuleEvaluationInterval = SchedulerBaseInterval * 6 // == 60 seconds
+	stateHistoryDefaultEnabled    = true
 )
 
 type UnifiedAlertingSettings struct {
@@ -85,6 +86,7 @@ type UnifiedAlertingSettings struct {
 	DefaultRuleEvaluationInterval time.Duration
 	Screenshots                   UnifiedAlertingScreenshotSettings
 	ReservedLabels                UnifiedAlertingReservedLabelSettings
+	StateHistory                  UnifiedAlertingStateHistorySettings
 }
 
 type UnifiedAlertingScreenshotSettings struct {
@@ -98,6 +100,10 @@ type UnifiedAlertingReservedLabelSettings struct {
 	DisabledLabels map[string]struct{}
 }
 
+type UnifiedAlertingStateHistorySettings struct {
+	Enabled bool
+}
+
 // IsEnabled returns true if UnifiedAlertingSettings.Enabled is either nil or true.
 // It hides the implementation details of the Enabled and simplifies its usage.
 func (u *UnifiedAlertingSettings) IsEnabled() bool {
@@ -304,6 +310,12 @@ func (cfg *Cfg) ReadUnifiedAlertingSettings(iniFile *ini.File) error {
 	}
 	uaCfg.ReservedLabels = uaCfgReservedLabels
 
+	stateHistory := iniFile.Section("unified_alerting.state_history")
+	uaCfgStateHistory := UnifiedAlertingStateHistorySettings{
+		Enabled: stateHistory.Key("enabled").MustBool(stateHistoryDefaultEnabled),
+	}
+	uaCfg.StateHistory = uaCfgStateHistory
+
 	cfg.UnifiedAlerting = uaCfg
 	return nil
 }