Modes

Hetscale runs in one of four modes per node group. The mode decides whether Hetscale may call the Hetzner API; it never changes how a decision is made or explained.

Observe

Read-only. While a project only observes, its Hetzner API token has read permission only, so Hetscale cannot create or delete anything even by mistake, and Hetzner is what enforces that. Once a node group of the project connects Read & Write on its Go Live page, one Read & Write token serves the whole project, and it is Hetscale’s own write gate that holds every write for a group which is not Live. It records every decision it would have taken, prefixed “would”. This is the trial mode: 14 days, a day-0 report from your last 30 days of metrics, and polling stops when the trial ends (Start observing). Per-group Observe is also a permanent feature of every plan. If a payment fails, or a cancelled plan reaches the end of its paid period, the plan keeps working for 14 more days; after that Hetscale only observes until a plan applies again. After a downgrade, new nodes above the new capacity wait until your fleet fits it (a replacement for a failed node never waits), and the Hetzner projects beyond the new plan only observe. Nodes are never destroyed.

Rehearsal

A supervised rehearsal before Live: Hetscale creates one short-lived server from your template, deploys through your adapter, waits for the load balancer health check, drains it and deletes it while you watch the timeline. The server is real and Hetzner bills at least one started hour. Success unlocks Live. Failure produces a report with the failing step and never leaves a node behind. Rehearsal shows the drain window in the timeline, so you see the effect of your setting before Live. It needs release v1 and the confirmed delete-protection step. Between its health check and its drain the server serves real requests; a run with no route within an hour fails and removes its server. The report shows each phase, the drain it waited and recommendations, and How fast is a scale-out explains the phases. You can repeat it, and each run bills a server.

Propose

Each scaling action is proposed with its reason and waits for approval in the dashboard; a mail links you to it. Unapproved proposals expire. Healing and your own schedules act on their own.

Live

Hetscale acts inside the minimum and maximum you set. Switching back to a safer mode takes effect immediately. Going Live requires a Read & Write token; Observe’s Read token cannot be upgraded, so you create a second one and connect it on the group’s Go Live page, where it takes the place of the Read token (Go Live).

Switching modes

A group moves to a safer mode at any time, with immediate effect. Live needs a passed Rehearsal, and Propose is a switch of a Live group. Decisions use the same inputs and rules in every mode: what Hetscale measures, the default thresholds and what holds a scale-in are on When Hetscale adds or removes a server.

Every action, in every mode, carries a line in the log with the trigger, the metric values at that moment, the rule that fired, the range it was allowed to act in, and the cost in node-hours.