Alerting: Add rule_query_offset setting for Prometheus rule conversion (#102500)

Adds a new configuration option to specify a time offset for rule evaluation, which gets applied and saved during the Prometheus -> Grafana conversion. For example:

[unified_alerting.prometheus_conversion]
rule_query_offset = 1m

Changing this option affects only the rules imported after the change. If query_offset is set at the group level, it takes precedence over this setting.

Default is set to 1m.

conf/defaults.ini

@@ -1515,6 +1515,16 @@ max_age =
 # Configures max number of alert annotations that Grafana stores. Default value is 0, which keeps all alert annotations.
 max_annotations_to_keep =
 
+[unified_alerting.prometheus_conversion]
+# Configuration options for converting Prometheus alerting and recording rules to Grafana rules.
+# These settings affect rules created via the Prometheus conversion API.
+
+# Offset the rule evaluation time for imported rules by a specified duration in the past.
+# This offset is applied and saved to the rule query during the conversion process from Prometheus to Grafana format.
+# The setting only affects rules imported after the configuration change is made and does not modify existing rules.
+# Accepts duration formats like: 30s, 1m, 1h.
+rule_query_offset = 1m
+
 [recording_rules]
 # Enable recording rules. You must provide write credentials below.
 enabled = false

conf/sample.ini

@@ -1496,6 +1496,16 @@ max_age =
 # Configures max number of alert annotations that Grafana stores. Default value is 0, which keeps all alert annotations.
 max_annotations_to_keep =
 
+[unified_alerting.prometheus_conversion]
+# Configuration options for converting Prometheus alerting and recording rules to Grafana rules.
+# These settings affect rules created via the Prometheus conversion API.
+
+# Offset the rule evaluation time for imported rules by a specified duration in the past.
+# This offset is applied and saved to the rule query during the conversion process from Prometheus to Grafana format.
+# The setting only affects rules imported after the configuration change is made and does not modify existing rules.
+# Accepts duration formats like: 30s, 1m, 1h.
+rule_query_offset = 1m
+
 #################################### Recording Rules #####################
 [recording_rules]
 # Enable recording rules. You must provide write credentials below.

pkg/services/ngalert/api/api_convert_prometheus.go

@@ -463,6 +463,7 @@ func (srv *ConvertPrometheusSrv) convertToGrafanaRuleGroup(
 				IsPaused: pauseAlertRules,
 			},
 			KeepOriginalRuleDefinition: util.Pointer(keepOriginalRuleDefinition),
+			EvaluationOffset:           &srv.cfg.PrometheusConversion.RuleQueryOffset,
 		},
 	)
 	if err != nil {

pkg/services/ngalert/prom/convert_test.go

@@ -179,6 +179,32 @@ func TestPrometheusRulesToGrafana(t *testing.T) {
 			},
 			expectError: false,
 		},
+		{
+			name:      "when global query offset is set, it should be used",
+			orgID:     1,
+			namespace: "some-namespace-uid",
+			promGroup: PrometheusRuleGroup{
+				Name:     "test-group-1",
+				Interval: prommodel.Duration(10 * time.Second),
+				Rules: []PrometheusRule{
+					{
+						Alert: "alert-1",
+						Expr:  "cpu_usage > 80",
+						For:   util.Pointer(prommodel.Duration(5 * time.Minute)),
+						Labels: map[string]string{
+							"severity": "critical",
+						},
+						Annotations: map[string]string{
+							"summary": "CPU usage is critical",
+						},
+					},
+				},
+			},
+			config: Config{
+				EvaluationOffset: util.Pointer(5 * time.Minute),
+			},
+			expectError: false,
+		},
 	}
 
 	for _, tc := range testCases {
@@ -244,8 +270,13 @@ func TestPrometheusRulesToGrafana(t *testing.T) {
 
 				require.Equal(t, expectedLabels, grafanaRule.Labels, tc.name)
 				require.Equal(t, promRule.Annotations, grafanaRule.Annotations, tc.name)
-				require.Equal(t, models.Duration(0*time.Minute), grafanaRule.Data[0].RelativeTimeRange.To)
-				require.Equal(t, models.Duration(10*time.Minute), grafanaRule.Data[0].RelativeTimeRange.From)
+
+				evalOffset := time.Duration(0)
+				if tc.config.EvaluationOffset != nil {
+					evalOffset = *tc.config.EvaluationOffset
+				}
+				require.Equal(t, models.Duration(evalOffset), grafanaRule.Data[0].RelativeTimeRange.To)
+				require.Equal(t, models.Duration(evalOffset+10*time.Minute), grafanaRule.Data[0].RelativeTimeRange.From)
 
 				originalRuleDefinition, err := yaml.Marshal(promRule)
 				require.NoError(t, err)

pkg/setting/setting_unified_alerting.go

@@ -112,6 +112,7 @@ type UnifiedAlertingSettings struct {
 	StateHistory                  UnifiedAlertingStateHistorySettings
 	RemoteAlertmanager            RemoteAlertmanagerSettings
 	RecordingRules                RecordingRuleSettings
+	PrometheusConversion          UnifiedAlertingPrometheusConversionSettings
 
 	// MaxStateSaveConcurrency controls the number of goroutines (per rule) that can save alert state in parallel.
 	MaxStateSaveConcurrency    int
@@ -165,6 +166,12 @@ type UnifiedAlertingReservedLabelSettings struct {
 	DisabledLabels map[string]struct{}
 }
 
+// UnifiedAlertingPrometheusConversionSettings contains configuration for converting Prometheus rules to Grafana format
+type UnifiedAlertingPrometheusConversionSettings struct {
+	// RuleQueryOffset defines a time offset to apply to rule queries during conversion from Prometheus to Grafana format
+	RuleQueryOffset time.Duration
+}
+
 type UnifiedAlertingStateHistorySettings struct {
 	Enabled       bool
 	Backend       string
@@ -437,6 +444,11 @@ func (cfg *Cfg) ReadUnifiedAlertingSettings(iniFile *ini.File) error {
 	}
 	uaCfg.StateHistory = uaCfgStateHistory
 
+	prometheusConversion := iniFile.Section("unified_alerting.prometheus_conversion")
+	uaCfg.PrometheusConversion = UnifiedAlertingPrometheusConversionSettings{
+		RuleQueryOffset: prometheusConversion.Key("rule_query_offset").MustDuration(time.Minute),
+	}
+
 	rr := iniFile.Section("recording_rules")
 	uaCfgRecordingRules := RecordingRuleSettings{
 		Enabled:              rr.Key("enabled").MustBool(false),