fix(gcp): price tiered SKUs from the first paid tier

providers/gcp/internal/skumatch/paid_rate_test.go

@@ -0,0 +1,35 @@
+package skumatch
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"google.golang.org/api/cloudbilling/v1"
+)
+
+func tier(units, nanos int64) *cloudbilling.TierRate {
+	return &cloudbilling.TierRate{UnitPrice: &cloudbilling.Money{CurrencyCode: "USD", Units: units, Nanos: nanos}}
+}
+
+func TestPaidRate(t *testing.T) {
+	free, paid, whole := tier(0, 0), tier(0, 50000000), tier(2, 0)
+	tests := []struct {
+		name string
+		expr *cloudbilling.PricingExpression
+		want *cloudbilling.TierRate
+	}{
+		{"nil expression", nil, nil},
+		{"no tiers", &cloudbilling.PricingExpression{}, nil},
+		{"single paid tier", &cloudbilling.PricingExpression{TieredRates: []*cloudbilling.TierRate{paid}}, paid},
+		{"free first tier then paid", &cloudbilling.PricingExpression{TieredRates: []*cloudbilling.TierRate{free, paid}}, paid},
+		{"first paid tier wins over later ones", &cloudbilling.PricingExpression{TieredRates: []*cloudbilling.TierRate{free, paid, whole}}, paid},
+		{"whole-unit price counts as paid", &cloudbilling.PricingExpression{TieredRates: []*cloudbilling.TierRate{free, whole}}, whole},
+		{"nil tier and nil price are skipped", &cloudbilling.PricingExpression{TieredRates: []*cloudbilling.TierRate{nil, {}, paid}}, paid},
+		{"all tiers free", &cloudbilling.PricingExpression{TieredRates: []*cloudbilling.TierRate{free, tier(0, 0)}}, nil},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Same(t, tt.want, PaidRate(tt.expr))
+		})
+	}
+}

providers/gcp/internal/skumatch/skumatch.go

@@ -97,3 +97,21 @@ func Slot(sku *cloudbilling.Sku) (PriceSlot, error) {
 	}
 	return 0, fmt.Errorf("sku %s has unrecognized usage type %q", sku.SkuId, sku.Category.UsageType)
 }
+
+// PaidRate returns the first tier whose unit price is non-zero, or nil when
+// every tier is free or has no price. The catalog lists tiers by ascending
+// StartUsageAmount, and a free allowance shows up as a leading zero-price
+// tier; the first non-zero tier is the marginal rate a workload sized for a
+// commitment pays, so it is the one to price from. Reading only the first
+// tier would treat a [free, paid] SKU as free and drop it.
+func PaidRate(expr *cloudbilling.PricingExpression) *cloudbilling.TierRate {
+	if expr == nil {
+		return nil
+	}
+	for _, rate := range expr.TieredRates {
+		if rate != nil && rate.UnitPrice != nil && (rate.UnitPrice.Units != 0 || rate.UnitPrice.Nanos != 0) {
+			return rate
+		}
+	}
+	return nil
+}

providers/gcp/services/cloudsql/client.go

@@ -459,12 +459,8 @@ func extractSQLPriceFromSKU(sku *cloudbilling.Sku) (price float64, currency stri
 	}
 
 	pricingInfo := sku.PricingInfo[0]
-	if pricingInfo.PricingExpression == nil || len(pricingInfo.PricingExpression.TieredRates) == 0 {
-		return 0, ""
-	}
-
-	rate := pricingInfo.PricingExpression.TieredRates[0]
-	if rate.UnitPrice == nil {
+	rate := skumatch.PaidRate(pricingInfo.PricingExpression)
+	if rate == nil {
 		return 0, ""
 	}
 

providers/gcp/services/cloudsql/tiered_rates_test.go

@@ -0,0 +1,42 @@
+package cloudsql
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/api/cloudbilling/v1"
+)
+
+// freeFirstTierSKU returns a SKU whose first tier is a free allowance and whose
+// second tier carries the paid rate (issue #242).
+func freeFirstTierSKU(id, description, usageType, region string, paidNanos int64) *cloudbilling.Sku {
+	sku := currencySKU(id, description, usageType, region, "USD", 0)
+	sku.PricingInfo[0].PricingExpression.TieredRates = append(sku.PricingInfo[0].PricingExpression.TieredRates,
+		&cloudbilling.TierRate{StartUsageAmount: 100, UnitPrice: &cloudbilling.Money{CurrencyCode: "USD", Nanos: paidNanos}})
+	return sku
+}
+
+func TestExtractSQLPricing_FreeFirstTierUsesPaidTier(t *testing.T) {
+	const tier, region = "db-n1-standard-1", "us-central1"
+	od := freeFirstTierSKU("od", tier+" Cloud SQL", "OnDemand", region, 50000000)
+
+	price, currency := extractSQLPriceFromSKU(od)
+	assert.InDelta(t, 0.05, price, 1e-12)
+	assert.Equal(t, "USD", currency)
+
+	onDemand, commitment, currency, err := extractSQLPricingFromSKUs([]*cloudbilling.Sku{
+		od,
+		freeFirstTierSKU("cud", tier+" Cloud SQL commitment 1yr", "Commit1Yr", region, 42000000),
+	}, tier, region)
+	require.NoError(t, err)
+	assert.InDelta(t, 0.05, onDemand, 1e-12)
+	assert.InDelta(t, 0.042, commitment, 1e-12)
+	assert.Equal(t, "USD", currency)
+}
+
+func TestExtractSQLPricing_AllTiersFreeIsSkipped(t *testing.T) {
+	sku := freeFirstTierSKU("od", "db-n1-standard-1 Cloud SQL", "OnDemand", "us-central1", 0)
+	price, _ := extractSQLPriceFromSKU(sku)
+	assert.Zero(t, price)
+}

providers/gcp/services/cloudstorage/client.go

@@ -321,12 +321,8 @@ func extractStoragePriceFromSKU(sku *cloudbilling.Sku) (price float64, currency
 	}
 
 	pricingInfo := sku.PricingInfo[0]
-	if pricingInfo.PricingExpression == nil || len(pricingInfo.PricingExpression.TieredRates) == 0 {
-		return 0, "", nil
-	}
-
-	rate := pricingInfo.PricingExpression.TieredRates[0]
-	if rate.UnitPrice == nil {
+	rate := skumatch.PaidRate(pricingInfo.PricingExpression)
+	if rate == nil {
 		return 0, "", nil
 	}
 

providers/gcp/services/cloudstorage/tiered_rates_test.go

@@ -0,0 +1,43 @@
+package cloudstorage
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/api/cloudbilling/v1"
+)
+
+// freeFirstTierStorageSKU returns a SKU whose first tier is a free allowance and
+// whose second tier carries the paid rate (issue #242).
+func freeFirstTierStorageSKU(description, usageType string, paidNanos int64) *cloudbilling.Sku {
+	sku := usageTypeSKU(description, usageType, 0)
+	sku.PricingInfo[0].PricingExpression.TieredRates = append(sku.PricingInfo[0].PricingExpression.TieredRates,
+		&cloudbilling.TierRate{StartUsageAmount: 5, UnitPrice: &cloudbilling.Money{CurrencyCode: "USD", Nanos: paidNanos}})
+	return sku
+}
+
+func TestExtractStoragePricing_FreeFirstTierUsesPaidTier(t *testing.T) {
+	od := freeFirstTierStorageSKU("STANDARD Storage in us-central1", "OnDemand", 20000000)
+
+	price, currency, err := extractStoragePriceFromSKU(od)
+	require.NoError(t, err)
+	assert.InDelta(t, 0.02/averageHoursPerMonth, price, 1e-15)
+	assert.Equal(t, "USD", currency)
+
+	onDemand, commitment, currency, err := extractStoragePricingFromSKUs([]*cloudbilling.Sku{
+		od,
+		freeFirstTierStorageSKU("STANDARD Storage in us-central1 Committed Use Discount", "Commit1Yr", 16000000),
+	}, "STANDARD", "us-central1")
+	require.NoError(t, err)
+	assert.InDelta(t, 0.02/averageHoursPerMonth, onDemand, 1e-15)
+	assert.InDelta(t, 0.016/averageHoursPerMonth, commitment, 1e-15)
+	assert.Equal(t, "USD", currency)
+}
+
+func TestExtractStoragePricing_AllTiersFreeIsSkipped(t *testing.T) {
+	sku := freeFirstTierStorageSKU("STANDARD Storage in us-central1", "OnDemand", 0)
+	price, _, err := extractStoragePriceFromSKU(sku)
+	require.NoError(t, err)
+	assert.Zero(t, price)
+}

providers/gcp/services/memorystore/client.go

@@ -427,12 +427,8 @@ func extractPriceFromSKU(sku *cloudbilling.Sku) (price float64, currency string)
 	}
 
 	pricingInfo := sku.PricingInfo[0]
-	if pricingInfo.PricingExpression == nil || len(pricingInfo.PricingExpression.TieredRates) == 0 {
-		return 0, ""
-	}
-
-	rate := pricingInfo.PricingExpression.TieredRates[0]
-	if rate.UnitPrice == nil {
+	rate := skumatch.PaidRate(pricingInfo.PricingExpression)
+	if rate == nil {
 		return 0, ""
 	}
 

providers/gcp/services/memorystore/tiered_rates_test.go

@@ -0,0 +1,42 @@
+package memorystore
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/api/cloudbilling/v1"
+)
+
+// freeFirstTierSKU returns a SKU whose first tier is a free allowance and whose
+// second tier carries the paid rate (issue #242).
+func freeFirstTierSKU(id, description, usageType, region string, paidNanos int64) *cloudbilling.Sku {
+	sku := currencySKU(id, description, usageType, region, "USD", 0)
+	sku.PricingInfo[0].PricingExpression.TieredRates = append(sku.PricingInfo[0].PricingExpression.TieredRates,
+		&cloudbilling.TierRate{StartUsageAmount: 100, UnitPrice: &cloudbilling.Money{CurrencyCode: "USD", Nanos: paidNanos}})
+	return sku
+}
+
+func TestExtractPricing_FreeFirstTierUsesPaidTier(t *testing.T) {
+	const tier, region = "STANDARD_HA", "us-central1"
+	od := freeFirstTierSKU("od", tier+" Memorystore", "OnDemand", region, 50000000)
+
+	price, currency := extractPriceFromSKU(od)
+	assert.InDelta(t, 0.05, price, 1e-12)
+	assert.Equal(t, "USD", currency)
+
+	onDemand, commitment, currency, err := extractPricingFromSKUs([]*cloudbilling.Sku{
+		od,
+		freeFirstTierSKU("cud", tier+" Memorystore commitment 1yr", "Commit1Yr", region, 42000000),
+	}, tier, region)
+	require.NoError(t, err)
+	assert.InDelta(t, 0.05, onDemand, 1e-12)
+	assert.InDelta(t, 0.042, commitment, 1e-12)
+	assert.Equal(t, "USD", currency)
+}
+
+func TestExtractPricing_AllTiersFreeIsSkipped(t *testing.T) {
+	sku := freeFirstTierSKU("od", "STANDARD_HA Memorystore", "OnDemand", "us-central1", 0)
+	price, _ := extractPriceFromSKU(sku)
+	assert.Zero(t, price)
+}