re add pricing model

Signed-off-by: Sean Holcomb <seanholcomb@gmail.com>

core/pkg/model/pricingmodel/pricingmodel.go

@@ -0,0 +1,69 @@
+package pricingmodel
+
+import (
+	"time"
+
+	"github.com/opencost/opencost/core/pkg/model/shared"
+)
+
+// TODO: assess whether we need any of this, or whether we can adapt all existing
+// references to it to use core/pkg/pricing concepts, instead.
+//
+// See:
+//   pkg/cloud/aws/pricinglistpricingsource.go
+//   pkg/cloud/azure/retailpricingsource.go
+//   pkg/cloud/gcp/billingpricingsource.go
+
+type PricingSource interface {
+	// PricingSourceType returns the instance type of the PricingSource, each implementation of this interface should
+	// provide a unique type that all instances should return
+	PricingSourceType() PricingSourceType
+	// PricingSourceKey returns the unique key of the PricingSource instance. In PricingSource implementation that may
+	// have multiple instances running side by side this key (derived from some configuration will) will Identify each
+	// instance. In PricingSource implementations where there will only be a single instance (ex Provider List Pricing)
+	// The PricingSourceKey should match the PricingSourceType
+	PricingSourceKey() string
+	GetPricing() (*PricingModelSet, error)
+}
+
+type PricingSourceType string
+
+type PricingModelSet struct {
+	TimeStamp   time.Time
+	SourceType  PricingSourceType
+	SourceKey   string
+	NodePricing map[NodeKey]NodePricing
+}
+
+// NewPricingModelSet creates a PricingModelSet with SourceKey initialized to sourceType.
+func NewPricingModelSet(timeStamp time.Time, sourceType PricingSourceType, sourceKey string) *PricingModelSet {
+	return &PricingModelSet{
+		TimeStamp:   timeStamp,
+		SourceType:  sourceType,
+		SourceKey:   sourceKey,
+		NodePricing: make(map[NodeKey]NodePricing),
+	}
+}
+
+type NodePricingType string
+
+const (
+	NodePricingTypeTotal   NodePricingType = "Total"
+	NodePricingTypeCPUCore NodePricingType = "CPUCore"
+	NodePricingTypeRamGB   NodePricingType = "RamGB"
+	NodePricingTypeDevice  NodePricingType = "Device"
+)
+
+type NodeKey struct {
+	Provider    shared.Provider
+	PricingType NodePricingType
+	UsageType   shared.UsageType
+	Region      string
+	NodeType    string
+	Family      string
+	DeviceType  string
+}
+
+type NodePricing struct {
+	HourlyRate float64
+}