Alerting: Enable group-level rule evaluation jittering by default, remove feature toggle (#82212)

* remove jitter feature flag

* Add an out so users can manually disable jitter

* Pass in cfg

* Add TODO to remove knob in future

conf/defaults.ini

@@ -1203,6 +1203,10 @@ max_state_save_concurrency = 1
 # The interval string is a possibly signed sequence of decimal numbers, followed by a unit suffix (ms, s, m, h, d), e.g. 30s or 1m.
 state_periodic_save_interval = 5m
 
+# Disables the smoothing of alert evaluations across their evaluation window.
+# Rules will evaluate in sync.
+disable_jitter = false
+
 [unified_alerting.screenshots]
 # Enable screenshots in notifications. You must have either installed the Grafana image rendering
 # plugin, or set up Grafana to use a remote rendering service.

conf/sample.ini

@@ -1130,6 +1130,10 @@
 # The interval string is a possibly signed sequence of decimal numbers, followed by a unit suffix (ms, s, m, h, d), e.g. 30s or 1m.
 ;state_periodic_save_interval = 5m
 
+# Disables the smoothing of alert evaluations across their evaluation window.
+# Rules will evaluate in sync.
+;disable_jitter = false
+
 [unified_alerting.reserved_labels]
 # Comma-separated list of reserved labels added by the Grafana Alerting engine that should be disabled.
 # For example: `disabled_labels=grafana_folder`

docs/sources/setup-grafana/configure-grafana/feature-toggles/index.md

@@ -55,7 +55,6 @@ Some features are enabled by default. You can disable these feature by setting t
 | `lokiQueryHints`                     | Enables query hints for Loki                                                                                                                                                                                                 | Yes                |
 | `alertingPreviewUpgrade`             | Show Unified Alerting preview and upgrade page in legacy alerting                                                                                                                                                            | Yes                |
 | `alertingQueryOptimization`          | Optimizes eligible queries in order to reduce load on datasources                                                                                                                                                            |                    |
-| `jitterAlertRules`                   | Distributes alert rule evaluations more evenly over time, by rule group                                                                                                                                                      |                    |
 
 ## Preview feature toggles
 

packages/grafana-data/src/types/featureToggles.gen.ts

@@ -168,7 +168,6 @@ export interface FeatureToggles {
   cloudRBACRoles?: boolean;
   alertingQueryOptimization?: boolean;
   newFolderPicker?: boolean;
-  jitterAlertRules?: boolean;
   jitterAlertRulesWithinGroups?: boolean;
   onPremToCloudMigrations?: boolean;
   alertingSaveStatePeriodic?: boolean;

pkg/services/featuremgmt/registry.go

@@ -1265,18 +1265,6 @@ var (
 			FrontendOnly: true,
 			Created:      time.Date(2024, time.January, 12, 12, 0, 0, 0, time.UTC),
 		},
-		{
-			Name:              "jitterAlertRules",
-			Description:       "Distributes alert rule evaluations more evenly over time, by rule group",
-			FrontendOnly:      false,
-			Stage:             FeatureStageGeneralAvailability,
-			Owner:             grafanaAlertingSquad,
-			AllowSelfServe:    false,
-			HideFromDocs:      false,
-			HideFromAdminPage: false,
-			RequiresRestart:   true,
-			Created:           time.Date(2024, time.January, 17, 12, 0, 0, 0, time.UTC),
-		},
 		{
 			Name:              "jitterAlertRulesWithinGroups",
 			Description:       "Distributes alert rule evaluations more evenly over time, including spreading out rules within the same group",

pkg/services/featuremgmt/toggles_gen.csv

@@ -149,7 +149,6 @@ enablePluginsTracingByDefault,experimental,@grafana/plugins-platform-backend,202
 cloudRBACRoles,experimental,@grafana/identity-access-team,2024-01-10,false,true,false
 alertingQueryOptimization,GA,@grafana/alerting-squad,2024-01-10,false,false,false
 newFolderPicker,experimental,@grafana/grafana-frontend-platform,2024-01-12,false,false,true
-jitterAlertRules,GA,@grafana/alerting-squad,2024-01-17,false,true,false
 jitterAlertRulesWithinGroups,preview,@grafana/alerting-squad,2024-01-17,false,true,false
 onPremToCloudMigrations,experimental,@grafana/grafana-operator-experience-squad,2024-01-22,false,false,false
 alertingSaveStatePeriodic,privatePreview,@grafana/alerting-squad,2024-01-22,false,false,false

pkg/services/featuremgmt/toggles_gen.go

@@ -607,10 +607,6 @@ const (
 	// Enables the nested folder picker without having nested folders enabled
 	FlagNewFolderPicker = "newFolderPicker"
 
-	// FlagJitterAlertRules
-	// Distributes alert rule evaluations more evenly over time, by rule group
-	FlagJitterAlertRules = "jitterAlertRules"
-
 	// FlagJitterAlertRulesWithinGroups
 	// Distributes alert rule evaluations more evenly over time, including spreading out rules within the same group
 	FlagJitterAlertRulesWithinGroups = "jitterAlertRulesWithinGroups"

pkg/services/ngalert/ngalert.go

@@ -274,7 +274,7 @@ func (ng *AlertNG) init() error {
 		BaseInterval:         ng.Cfg.UnifiedAlerting.BaseInterval,
 		MinRuleInterval:      ng.Cfg.UnifiedAlerting.MinInterval,
 		DisableGrafanaFolder: ng.Cfg.UnifiedAlerting.ReservedLabels.IsReservedLabelDisabled(models.FolderTitleLabel),
-		JitterEvaluations:    schedule.JitterStrategyFrom(ng.FeatureToggles),
+		JitterEvaluations:    schedule.JitterStrategyFrom(ng.Cfg.UnifiedAlerting, ng.FeatureToggles),
 		AppURL:               appUrl,
 		EvaluatorFactory:     evalFactory,
 		RuleStore:            ng.store,

pkg/services/ngalert/schedule/jitter.go

@@ -7,6 +7,7 @@ import (
 	"github.com/grafana/grafana-plugin-sdk-go/data"
 	"github.com/grafana/grafana/pkg/services/featuremgmt"
 	ngmodels "github.com/grafana/grafana/pkg/services/ngalert/models"
+	"github.com/grafana/grafana/pkg/setting"
 )
 
 // JitterStrategy represents a modifier to alert rule timing that affects how evaluations are distributed.
@@ -19,14 +20,14 @@ const (
 )
 
 // JitterStrategyFrom returns the JitterStrategy indicated by the current Grafana feature toggles.
-func JitterStrategyFrom(toggles featuremgmt.FeatureToggles) JitterStrategy {
+func JitterStrategyFrom(cfg setting.UnifiedAlertingSettings, toggles featuremgmt.FeatureToggles) JitterStrategy {
-	strategy := JitterNever
+	strategy := JitterByGroup
+	if cfg.DisableJitter {
+		return JitterNever
+	}
 	if toggles == nil {
 		return strategy
 	}
-	if toggles.IsEnabledGlobally(featuremgmt.FlagJitterAlertRules) {
-		strategy = JitterByGroup
-	}
 	if toggles.IsEnabledGlobally(featuremgmt.FlagJitterAlertRulesWithinGroups) {
 		strategy = JitterByRule
 	}

pkg/setting/setting_unified_alerting.go

@@ -83,6 +83,7 @@ type UnifiedAlertingSettings struct {
 	MaxAttempts                    int64
 	MinInterval                    time.Duration
 	EvaluationTimeout              time.Duration
+	DisableJitter                  bool
 	ExecuteAlerts                  bool
 	DefaultConfiguration           string
 	Enabled                        *bool // determines whether unified alerting is enabled. If it is nil then user did not define it and therefore its value will be determined during migration. Services should not use it directly.
@@ -300,6 +301,10 @@ func (cfg *Cfg) ReadUnifiedAlertingSettings(iniFile *ini.File) error {
 
 	uaCfg.BaseInterval = SchedulerBaseInterval
 
+	// TODO: This was promoted from a feature toggle and is now the default behavior.
+	// We can consider removing the knob entirely in a release after 10.4.
+	uaCfg.DisableJitter = ua.Key("disable_jitter").MustBool(false)
+
 	// The base interval of the scheduler for evaluating alerts.
 	// 1. It is used by the internal scheduler's timer to tick at this interval.
 	// 2. to spread evaluations of rules that need to be evaluated at the current tick T. In other words, the evaluation of rules at the tick T will be evenly spread in the interval from T to T+scheduler_tick_interval.