GCP Discount Findings: Committed Use Discounts and Spot VMs
Committed use discounts reward steady usage and Spot rewards tolerance. ZopNight checks the evidence for each before it suggests either.
GCP has two main discount levers ZopNight recommends: committed use discounts (CUDs) for workloads that run steadily, and Spot capacity for workloads that can be interrupted. The rules for each look at different evidence, and both price the saving from Google’s own live rates rather than a flat discount.
Committed use discounts
- GCP Prod VM Without Committed Use Discount targets production VMs.
- GCP Cloud SQL Committed Use Discount Opportunity targets production Cloud SQL instances, identified by name or by an environment label.
Both pass a commitment-discipline gate before they fire: at least 60 days of history, high measured uptime, and meaningful CPU and memory use. A database that is mostly idle should be rightsized or scheduled first, not locked into a commitment. The Cloud SQL rule reads Cloud SQL’s own CPU and memory metrics rather than generic VM metrics. Options are priced for each 1-year and 3-year term available in the GCP pricing catalog, and a break-even gate suppresses any that do not clearly pay back.
One limitation is stated plainly in the rule reference. Resource-based GCP CUDs cover aggregate usage for a region and machine configuration, not a named VM, and ZopNight does not yet mark individual VMs as CUD-covered. A VM already covered by a CUD can therefore still see this suggestion, so check existing commitments before buying. More on committed use discounts.
Spot
- GCP Spot VM Opportunity needs positive evidence that a VM is non-production, from an environment label or a dev/test name. A production label always wins over a dev-looking name. It also skips VMs named for disaster recovery or standby roles and Windows VMs.
- GKE Spot Node Pool Opportunity is simpler: the rule treats a node pool as structurally safer on Spot, because the cluster autoscaler can reschedule preempted pods across the pool. It skips pools already on Spot.
Savings come from the live on-demand and Spot rates for the machine type. Background on Spot instances and preemptible instances.
How GCP costs are read
For billing-connected projects, ZopNight reads costs from the BigQuery billing export net of credits, so committed-use, sustained-use and promotional credits already reduce the figures these rules start from.
Related
Discounts sit on top of the GCP rightsizing findings. Fact sheets: Compute Engine, Cloud SQL, GKE node pools. Service pages: GCP Compute Engine, GCP Cloud SQL. Full list: GCP recommendations.
Questions we get a lot.
Will ZopNight buy a committed use discount?
No. Commitment recommendations are advisory. ZopNight shows the priced options and the evidence behind them, and the purchase stays with you.
Why am I seeing a CUD suggestion for a VM that is already covered?
GCP CUDs are not attached to individual VMs, and ZopNight does not yet mark a single VM as CUD-covered. Review your existing commitments before acting on the suggestion.