Cloud Cost Metrics

When ingesting billing data from cloud service providers (CSP), Kubecost records multiple cost metrics for each item. These cost metrics represent different pricing models which may be useful depending on what needs to be accomplished. The cost metrics currently supported by Cloud Cost are:

• ListCost

• NetCost

• AmortizedNetCost

• InvoicedCost

• AmortizedCost

Each cost metric includes a Cost and a KubernetesPercent field. An unaggregated CloudCost query should have a 1 or a 0 in the KubernetesPercent field of all of its cost metrics. When it becomes aggregated, this value can become a percentage. It is necessary to keep track of these separately because differences in cost metrics will cause this value to diverge. For example, aggregating a Cloud Cost representing a Kubernetes node that has a reserved instance applied to it, and a non-Kubernetes node of the same type but with no reserved instance discount. See below:

Node1 {
    ListCost: {
        Cost: 2,
        KubernetesPercent: 1.0,
    },
    AmortizedNetCost: {
        Cost:  1,
        KubernetesPercent: 1.0
    },
}

Node2 {
    ListCost: {
        Cost: 2,
        KubernetesPercent: 0.0,
    },
    AmortizedNetCost: {
        Cost:  2,
        KubernetesPercent: 0.0
    },
}

agg {
    ListCost: {
        Cost: 4,
        KubernetesPercent: 0.5,
    },
    AmortizedNetCost: {
        Cost:  3,
        KubernetesPercent: 0.33
    },

}

The KubernetesPercent on the AmortizedNetCost is calculated at 33% from $1 which was 100% Kubernetes spend and $2 that were 0% Kubernetes spend in that dimension.

Cost metrics by CSP

The current Cloud Cost schema is optimistic in that it provides space for cost metrics that may not yet be available from some providers. As the FOCUS Spec gains more adoption among CSPs, all fields will be populated with values that match the definitions. For now, some values on certain providers are being populated with their nearest approximate. This section outlines how each value is populated on each CSP.

AWS cost metrics

Of all billing exports and APIs, the Cost and Usage Report (CUR) has the most robust set of cost metrics, and currently has the best support. Depending on what kind of discounts or resources a user has, the schema changes, therefore many of these columns are populated dynamically to support all users. In particular, any _net_ column will only be available if the user has a discount that causes it to exist. Additionally, Kubecost currently only considers line items that have a line_item_line_item_type of Usage, DiscountUsage, SavingsPlanCoveredUsage, EdpDiscount, or PrivateRateDiscount.

More information on the columns and their definitions can be found in AWS' Line item details documentation.

List Cost

To populate list price, Kubecost uses pricing_public_on_demand_cost.

Net Cost

Kubecost uses line_item_net_unblended_cost if available. If not, Kubecost uses line_item_unblended_cost.

Amortized Net Cost

If _net_ is not available, Kubecost uses Amortized Cost

If line_item_line_item_type is DiscountUsage, Kubecost uses reservation_net_effective_cost.

If line_item_line_item_type is SavingsPlanCoveredUsage, Kubecost uses savings_plan_net_savings_plan_effective_cost.

Default to line_item_net_unblended_cost.

Invoiced Cost

Kubecost uses Net Cost.

Amortized Cost

If line_item_line_item_type is DiscountUsage, Kubecost uses reservation_effective_cost.

If line_item_line_item_type is SavingsPlanCoveredUsage, Kubecost uses savings_plan_savings_plan_effective_cost.

Default to line_item_unblended_cost.

GCP cost metrics

Cloud Cost uses a detailed billing export accessed via BigQuery to interface with GCP. This export provides Kubecost with a Cost column with a float value in addition to an array of credit objects per item. These credits are various discounts applied to the item being referenced.

More details about the export can be found in GCP's Structure of Detailed data export.

List Cost

The Cost column for the line item.

Net Cost

The Cost column plus the sum of all credit amounts.

Amortized Net Cost

Amortized Net Cost is Cost with all credits and amortized CUD payments amortizedNetCost := cost + creditAmount + cudCreditAmount + flexibleCUDCreditAmount + flexibleCUDNetPayedAmount

Invoiced Cost

Kubecost uses Net Cost.

Amortized Cost

Amortized Cost is Cost plus CUD credits and amortized CUD payments amortizedCost := cost + cudCreditAmount + flexibleCUDCreditAmount + flexibleCUDPayedAmount

Azure cost metrics

The Azure billing export can be set to amortized or not amortized during creation. Depending on this, either the Net Cost Metric or Amortized Net Cost metric will be accurate. Additionally the Azure export has multiple schema depending on when it was created and what kind of account the user has. There are also localized versions of the headers.

List Cost

Kubecost usespaygcostinbillingcurrency if available, otherwise Kubecost uses Net Cost

Net Cost

Kubecost uses costinbillingcurrency. If not available, Kubecost uses pretaxcost, and if that isn't available, Kubecost uses cost.

Amortized Net Cost

Kubecost uses Net Cost.

Invoiced Cost

Kubecost uses Net Cost.

Amortized Cost

Kubecost uses Net Cost.

Kubernetes clusters

To calculate the 'K8s Utilization', Kubecost must first determine if a resources is part of a Kubernetes cluster or not.

If a tag or label in the list below is present on the billing export, Kubecost will consider those costs part of the 'K8s Utilization' calculation. This will not always be 100% accurate in all situations.

AWS

In AWS, Kubecost will identify the line item in the bill as a Kubernetes resource if line_item_product_code is AmazonEKS, or one of the following label keys is present:

• resource_tags_aws_eks_cluster_name

• resource_tags_user_eks_cluster_name

• resource_tags_user_alpha_eksctl_io_cluster_name

• resource_tags_user_kubernetes_io_service_name

• resource_tags_user_kubernetes_io_created_for_pvc_name

• resource_tags_user_kubernetes_io_created_for_pv_name

GCP

The billing report has a Tags column which contains a Record of key values pairs. Kubecost checks for the presence of the following keys which may not have associated value:

• goog-gke-volume

• goog-gke-node

• goog-k8s-cluster-name

Azure

The billing export has a tags column with a JSON string of key values pairs. Kubecost checks for the presence of keys with the following prefixes:

• aks-managed

• kubernetes.io-created

• k8s-azure-created