Alerting: Metric to count imported from Prometheus rules (#100847)

pkg/services/ngalert/models/alert_rule.go

@@ -397,19 +397,18 @@ func WithoutInternalLabels() LabelOption {
 }
 
 func (alertRule *AlertRule) ImportedFromPrometheus() bool {
-	if alertRule.Metadata.PrometheusStyleRule == nil {
-		return false
-	}
-
-	return alertRule.Metadata.PrometheusStyleRule.OriginalRuleDefinition != ""
+	_, err := alertRule.PrometheusRuleDefinition()
+	return err == nil
 }
 
-func (alertRule *AlertRule) PrometheusRuleDefinition() string {
-	if !alertRule.ImportedFromPrometheus() {
-		return ""
+func (alertRule *AlertRule) PrometheusRuleDefinition() (string, error) {
+	if alertRule.Metadata.PrometheusStyleRule != nil {
+		if alertRule.Metadata.PrometheusStyleRule.OriginalRuleDefinition != "" {
+			return alertRule.Metadata.PrometheusStyleRule.OriginalRuleDefinition, nil
+		}
 	}
 
-	return alertRule.Metadata.PrometheusStyleRule.OriginalRuleDefinition
+	return "", fmt.Errorf("prometheus rule definition is missing")
 }
 
 // GetLabels returns the labels specified as part of the alert rule.

pkg/services/ngalert/models/alert_rule_test.go

@@ -1017,3 +1017,70 @@ func TestGeneratorFillsAllFields(t *testing.T) {
 
 	require.FailNow(t, "AlertRule generator does not populate fields", "skipped fields: %v", maps.Keys(fields))
 }
+
+func TestAlertRule_PrometheusRuleDefinition(t *testing.T) {
+	tests := []struct {
+		name             string
+		rule             AlertRule
+		expectedResult   string
+		expectedErrorMsg string
+	}{
+		{
+			name: "rule with prometheus definition",
+			rule: AlertRule{
+				Metadata: AlertRuleMetadata{
+					PrometheusStyleRule: &PrometheusStyleRule{
+						OriginalRuleDefinition: "groups:\n- name: example\n  rules:\n  - alert: HighRequestLatency\n    expr: request_latency_seconds{job=\"myjob\"} > 0.5\n    for: 10m\n    labels:\n      severity: page\n    annotations:\n      summary: High request latency",
+					},
+				},
+			},
+			expectedResult:   "groups:\n- name: example\n  rules:\n  - alert: HighRequestLatency\n    expr: request_latency_seconds{job=\"myjob\"} > 0.5\n    for: 10m\n    labels:\n      severity: page\n    annotations:\n      summary: High request latency",
+			expectedErrorMsg: "",
+		},
+		{
+			name: "rule with empty prometheus definition",
+			rule: AlertRule{
+				Metadata: AlertRuleMetadata{
+					PrometheusStyleRule: &PrometheusStyleRule{
+						OriginalRuleDefinition: "",
+					},
+				},
+			},
+			expectedResult:   "",
+			expectedErrorMsg: "prometheus rule definition is missing",
+		},
+		{
+			name: "rule with nil prometheus style rule",
+			rule: AlertRule{
+				Metadata: AlertRuleMetadata{
+					PrometheusStyleRule: nil,
+				},
+			},
+			expectedResult:   "",
+			expectedErrorMsg: "prometheus rule definition is missing",
+		},
+		{
+			name:             "rule with empty metadata",
+			rule:             AlertRule{},
+			expectedResult:   "",
+			expectedErrorMsg: "prometheus rule definition is missing",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := tt.rule.PrometheusRuleDefinition()
+			isPrometheusRule := tt.rule.ImportedFromPrometheus()
+
+			if tt.expectedErrorMsg != "" {
+				require.Error(t, err)
+				require.Equal(t, tt.expectedErrorMsg, err.Error())
+				require.False(t, isPrometheusRule)
+			} else {
+				require.NoError(t, err)
+				require.Equal(t, tt.expectedResult, result)
+				require.True(t, isPrometheusRule)
+			}
+		})
+	}
+}