Share resource-based CUDs across projects

This document explains how you can share resource-based committed use discounts (CUDs) across projects in your Cloud Billing account.

By default, resource-based CUDs from a commitment are limited to the project in which that commitment was purchased. You can change the commitment scope for your Cloud Billing and share these CUDs across projects that are linked to that Cloud Billing.

How CUD sharing works

By default, resource-based CUDs apply at the project level and you receive the applicable CUDs only for the project in which you purchase the commitment. If you move the project for which you purchased your commitment to a different Cloud Billing account, then you continue to receive the applicable CUDs for that project under the new Cloud Billing account.

However, Compute Engine lets you share discounts for resource-based commitments across multiple projects that share the same Cloud Billing account. Sharing your resource-based CUDs for commitments across all your projects reduces the overhead of managing discounts on a per-project basis, and maximizes your savings by pooling all your discounts across your projects' resource usage.

If you have multiple projects that share the same Cloud Billing account, then you can enable CUD sharing so that all of your projects within that Cloud Billing account share CUDs from all of your resource-based commitments.

For example, you purchase two resource-based commitments for 80 cores each (a total of 160 cores) and you run 200 cores during the month across different projects in your Cloud Billing account. If you've enabled CUD sharing for your Cloud Billing account, then you receive the applicable resource-based CUDs for 160 of those 200 cores that are used across the projects in that Cloud Billing account. The additional 40 cores are billed at on-demand, non-committed use rates. After you purchase your commitments, you're billed for your committed resources monthly, throughout the commitment time period, even if you don't use the resources. See Understand discount sharing for cost-saving utilization recommendations.

Attribution for shared CUDs

Attribution refers to how Google Cloud allocates your CUDs across projects after you enable CUD sharing. These allocations are reflected in Cloud Billing cost management interfaces, such as the usage cost export or the Google Cloud console .

You can choose one of the following types of attribution:

• Proportional attribution . Your CUDs are shared across projects based on each project's proportion of the total eligible usage. This is the default attribution type.
• Prioritized attribution . You specify the order in which projects receive CUDs.

Proportionally attributed commitments are applied to usage from projects based on each project's share of the total eligible usage. For example, suppose project A consumes US$75 worth of usage and project B consumes US$25 worth of usage, then project A gets covered by up to 75% of the available CUDs and project B gets covered by up to 25%.

Prioritized attribution applies your commitments to usage based on the distribution settings that you specify. You can choose the projects, along with the amount of usage within each project, that get covered by the commitments. After your prioritized commitments are applied to eligible usage, any remaining unprioritized commitments are applied proportionally to the eligible usage in your remaining projects. The total amount of the allotments cannot exceed the commitment amount purchased.

You can update attribution preferences anytime during the commitment's lifetime. However, any attribution preferences that you configure are applied only after you enable CUD sharing. To choose proportional or prioritized attribution for your Compute Engine commitments, see choose attribution for resource-based commitments .

Limitations

• If you have a shared reservation and also enabled CUD sharing for your commitment's Cloud Billing account, then, to make sure that usage from your consumed shared reservation is eligible for resource-based CUDs, you must share your reservation only with projects that are linked to the commitment's Cloud Billing account. Doing so helps you avoid being charged at on-demand rates for usage that is eligible for CUDs.
• When you enable CUD sharing for a Cloud Billing account, if any portion of a commitment is unutilized, then the remaining commitment charge remains in the project where you purchased that commitment.

Check whether CUD sharing is enabled

You can check the CUD sharing status for your Cloud Billing account on the CUD analysis dashboard. The steps you must follow depend on whether or not you opted into the new spend-based CUD model . Follow the steps that apply to your model.

Enable CUD sharing

To share the CUDs from your resource-based commitments across eligible usage in all projects linked to your Cloud Billing account, enable CUD sharing by changing the commitment scope from Projectto Billing accountin the Google Cloud console. After you change your commitment scope to Billing account, CUD sharing is enabled on all of the current and future projects associated with the Cloud Billing account.

CUD sharing works in conjunction with your attribution configuration. Unless you configure your attribution preferences first, when you enable CUD sharing, it defaults to using proportional attribution for your Compute Engine resource-based commitments. If you want to configure your attribution configuration before you enable CUD sharing , see choose attribution for resource-based commitments for more information and how to enable each type of attribution.

Permissions required for this task

To perform this task, you must have the following permissions :

You need specific permissions on the Cloud Billing account to access billing account information. To update the commitment scope to enable CUD sharing, you need a role that includes the following permission on the Cloud Billing account:

• billing.subscriptions.update on the Cloud Billing account

To gain this permission using a predefined role, ask your billing administrator to grant you the Billing Account Administrator role on the Cloud Billing account.

The procedure to enable CUD sharing changes depending on whether or not you opted into the new spend-based CUD model . Follow the steps that apply to your model.

What's next

• Learn about attribution for resource-based commitments .
• Learn how to analyze the effectiveness of your CUDs .