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BigFleet Providers

Pricing & interruption

BigFleet ranks capacity by effective cost = price_per_hour + interruption_probability × penalty. So a provider has to report both honestly. On Hetzner Cloud the story is unusually simple, and this page explains exactly why.

price_per_hour — published Hetzner rates, in USD

Hetzner publishes a fixed hourly on-demand price per server type per location, in EUR. The provider sources that rate from the Hetzner ServerType API (ServerType.Pricings), picks the entry for the machine’s location, takes the hourly (not monthly) gross figure, and converts it to USD with the --eur-usd rate:

price_per_hour (USD) = hetzner_hourly_gross_EUR × --eur-usd
  • The rate is configurable (--eur-usd, default 1.08). The cost field is a relative ranking signal, so an approximate rate is fine, but pin a current one and refresh it periodically — a stale rate skews effective-cost across the whole fleet. Set it per deployment.
  • Prices are cached and refreshed off the hot path. At startup, and every --price-refresh (default 30m), the provider refreshes the price for each offered (server_type, location) pair. List/Get read the cache and never block on the pricing API.
  • A pinned EUR table is the fallback. Common cx/cpx/cax/ccx types have pinned EU-baseline hourly prices, so the fake backend, credential-free conformance, and a pricing-API outage all still produce a sensible price_per_hour. Live Hetzner data overlays it (and picks up the small US-location premium for ash / hil).

interruption_probability — a genuine zero

interruption_probability is the hourly chance the provider reclaims the machine out from under the workload. It is provider-declared only — no cluster can override it.

Hetzner Cloud is on-demand only. There is no spot/preemptible market. Hetzner does not reclaim a running on-demand server to satisfy other demand. So the correct, real, provider-declared value is exactly 0.0 for every machine.

This is the important distinction the conformance program checks: a zero here is not a skipped or forgotten field — it is the true value for this substrate. That is different from a spot machine declared at 0, which would be a bug (effective_cost would understate the real risk and the machine would win high-penalty workloads it should never get). Because Hetzner Cloud has no spot tier, the provider:

  • declares capacity_type = ON_DEMAND for every machine,
  • sets interruption_probability = 0.0,
  • and does not claim the spot conformance profile — so the SPOT-interruption_probability > 0 behaviors skip-as-pass rather than apply.

The provider also rejects a spot capacity_type in an offering at startup, rather than silently mis-declaring a zero interruption probability for capacity that doesn’t exist.

If Hetzner ever ships a spot tier

The contract is ready for it. If Hetzner introduces a real preemptible market, the correct change is to set capacity_type = SPOT and a real, non-zero interruption forecast for those machines (observed where possible, forecast for Speculative slots), and to claim the spot profile. Never leave a spot machine at 0.

Bare metal (Robot) — out of scope here

This provider serves Hetzner Cloud. If you build the Hetzner dedicated / Robot substrate instead, the cost story flips: capacity_type = BARE_METAL, price_per_hour = 0 (the hardware is already owned/paid for), and interruption_probability = 0 (owned hardware is not reclaimed). That is a separate substrate with its own profile (bare-metal, where Delete is Unimplemented); it is not what the Cloud provider on this page does.