Cost Optimizer

Illustrative example — demonstrates a well-formed SKILL.md for this reference implementation. Adapt the content to your own org; do not deploy verbatim.

cost-optimizer

Overview

Turns Databricks billing data into finance-facing optimization actions: it measures commitment/discount coverage, compares actual spend against budget, and forecasts month-end DBU cost so the FinOps/platform team can act before overruns land. Distinct from pipeline-cost-analyzer (which is engineering-facing job/SKU analysis) — this skill is scoped to budget governance and dollarized recommendations.

When to use this skill

When a finance user asks about budget adherence, discount coverage, or spend forecasting:

• "Are we on track against this month's Databricks budget?"
• "What share of our DBUs are covered by our committed-use discount?"
• "Project our month-end spend at the current run rate."
• "Where is spend running over budget by product?"

Instructions

1. Establish the budget baseline — ask for the monthly budget if not supplied; otherwise compare against the trailing 3-month average as an implicit baseline.
2. Dollarize usage — join system.billing.usage to system.billing.list_prices to convert DBUs to cost; never present raw DBUs alone to a finance audience.
3. Assess coverage and variance — compute committed-discount coverage and budget variance.
4. Forecast — extrapolate month-to-date run rate to a month-end projection.
5. Recommend — give 2–3 dollar-quantified actions, ordered by savings impact.

Examples

Month-end spend forecast at current run rate

WITH mtd AS (
  SELECT
    SUM(u.usage_quantity * p.pricing.default) AS cost_to_date,
    DAY(CURRENT_DATE())                        AS days_elapsed,
    DAY(LAST_DAY(CURRENT_DATE()))              AS days_in_month
  FROM system.billing.usage u
  JOIN system.billing.list_prices p
    ON u.sku_name = p.sku_name
  WHERE u.usage_date >= DATE_TRUNC('month', CURRENT_DATE())
)
SELECT
  cost_to_date,
  ROUND(cost_to_date / days_elapsed * days_in_month, 2) AS projected_month_end
FROM mtd

Spend by product vs. trailing average (budget-variance signal)

SELECT
  billing_origin_product,
  SUM(usage_quantity)                                            AS dbus_this_month
FROM system.billing.usage
WHERE usage_date >= DATE_TRUNC('month', CURRENT_DATE())
GROUP BY 1
ORDER BY dbus_this_month DESC

Recommendations framework

Every response ends with dollar-quantified actions:

1. Biggest variance — the product/workspace most over baseline, with an estimated monthly-dollar impact and one corrective action.
2. Coverage gap — uncommitted spend that a committed-use discount would cover, with the estimated discount saving.
3. Quick win — one action realizable this billing cycle (e.g. move a recurring batch job off all-purpose compute).

Edge cases

• Missing budget — if no budget is provided, state the baseline you used (trailing 3-month average) so the variance is interpretable.
• Early in the month — a run-rate forecast on <5 elapsed days is noisy; flag the low confidence rather than presenting a point estimate as firm.
• Price coverage — if a sku_name has no row in list_prices, report it as unpriced rather than silently dropping its usage from the cost total.

Data scope

• system.billing.usage — DBU consumption events per workspace/SKU/job/cluster
• system.billing.list_prices — list prices per SKU (for dollarization)
• No PII or sensitive customer data is accessed.