# Tune GCP MIG Autoscaler: Targets and Cooldowns > ZopNight schedules GCP Managed Instance Groups on GCP to run on your team's hours and stop the rest of the time. Read-only setup, dependency-aware, production excluded by default. Source: https://zop.dev/zopnight/gcp/mig Published: 2026-07-01 · Author: avinash-gaurav · Tags: zopnight, gcp, compute, scheduling --- Most of what teams spend on GCP Managed Instance Groups in non-production is spent while nobody is watching. In a development, staging, or QA account these resources are billed for every hour they exist, but the people who use them work a fraction of those hours. Nights, weekends, holidays, and the long tail of "we'll get back to that environment next sprint" all meter at full price. ZopNight closes that gap by scheduling your GCP Managed Instance Groups to run on your team's hours and stop the rest of the time, without touching your data and without a migration. It is the most direct lever in [FinOps](https://zop.dev/learn/finops), and for teams comparing tools it is where ZopNight pulls ahead of dashboard-first platforms like [CloudHealth](https://zop.dev/compare/cloudhealth-vs-zopnight). ## Why GCP Managed Instance Groups cost more than they should Cloud providers bill GCP Managed Instance Groups by the hour whether or not anyone is using them, and most non-production fleets default to running 24/7 out of habit rather than need. At typical on-demand rates ($0.05–$5.00/hr per MIG) an always-on instance quietly bills the same on a Tuesday afternoon as it does at 3 AM on a Sunday. Here is the shape of it. Say a box runs at a typical on-demand rate of $0.17 an hour. Left on around the clock that is about $124 a month, because a month is roughly 730 hours. Confine it to a single-shift work week, about 50 hours, and you pay for 50 hours instead of 730. Your own rate and hours will differ, but the ratio is the point: in non-production, most of the meter runs while nobody is working. The instinct is usually to reach for a smaller instance type. But rightsizing only helps a resource that is genuinely too big; it does nothing for a correctly-sized resource that simply runs when no one is around. The larger, easier win is refusing to pay for the hours nobody is working, and it carries none of the performance risk of down-sizing a box that might spike tomorrow. ## Stopping and starting GCP Managed Instance Groups safely ZopNight handles the Apply tuned autoscaler config via GCP MIG Autoscaler API on every GCP Managed Instance Groups in scope, in dependency order so nothing comes up before what it depends on. A scheduled stop preserves your data exactly as a normal power-off would; ZopNight never terminates or deletes the resource, and idle detection watches CPU, network, and disk signals to surface the GCP Managed Instance Groups that are running but doing nothing. In practice the setup is: Connect your GCP project. ZopNight discovers all MIGs via Cloud Asset Inventory; Smart defaults read 14 days of CPU and request metrics from Cloud Monitoring and suggest min, max, target, and cooldown; Pick monitor, recommend, or autopilot mode; Apply writes the autoscaler via Autoscalers.Insert or Autoscalers.Update with ForceSendFields:["ScalingSchedules"] so cancel actually deletes scheduled scale-ups instead of silently merging. If you run GCP Managed Instance Groups you probably also run [Compute Engine](https://zop.dev/zopnight/gcp/compute-engine), [GKE](https://zop.dev/zopnight/gcp/gke), [Cloud RUN](https://zop.dev/zopnight/gcp/cloud-run), and scheduling them together is where the dependency ordering earns its keep. Related reading: [autoscaling](https://zop.dev/solutions/autoscaling) and [event readiness](https://zop.dev/solutions/event-readiness). ## How ZopNight schedules GCP Managed Instance Groups The loop that does this is deliberately mechanical, and it starts read-only. You connect GCP with a read-only role, and ZopNight discovers every GCP Managed Instance Groups across your regions and accounts. It records a per-action permission verdict for each one, so you can see where it can list a resource but not yet stop it, and you review that inventory, filter it by status or type, and search for the specific resources you care about before anything is scheduled. Scheduling itself is a cron you write once in plain terms, stop at 7 PM, start at 8 AM on weekdays, pinned to your timezone so the jobs fire at local business hours rather than UTC. A weekly 24-hour grid shows the schedule visually so you catch gaps and overlaps before you save, and an estimate of active versus inactive hours appears before you commit. Resources attach individually or bundle into groups like "dev-cluster" or "staging-db" so a whole environment follows one cadence. Actions run in dependency order, so a database comes up before the app server that depends on it. When something needs to stay up, an override forces a GCP Managed Instance Groups ON or OFF for a defined window, carries a reason so teammates understand why it exists, and expires automatically so nothing is left running by accident. If a start or stop fails, ZopNight retries up to three times and falls back to a dead-letter queue rather than silently dropping the action, and every state change lands in an audit trail that records whether a schedule, an override, or a specific user triggered it. ## Getting started Getting started is intentionally low-stakes: - Connect GCP with a read-only role. Nothing is scheduled or changed at this stage. - Let ZopNight discover your GCP Managed Instance Groups and review exactly what it found, filtered by account, region, and status. - Create a schedule in your timezone and attach the non-production resources or groups you want it to cover. - Watch the first cycle run, with Slack, Teams, or Google Chat notifications on every start, stop, and failure, then layer in idle cleanup and guided rightsizing. Production stays excluded by default throughout, and because discovery and recommendations are read-only, you can prove the value before you enable a single action. ## Frequently asked questions ### Why does cancel on GCP MIG use Autoscalers.Update instead of PATCH? PATCH merges map keys, so deleting a scalingSchedule via PATCH silently leaves the stale entry. ZopNight uses Update with ForceSendFields:["ScalingSchedules"] so the cancel actually wipes the schedule. The README in backend/executor/internal/provider/gcp documents this. ### Does ZopNight handle pre-scaling for product launches on MIG? Yes. Event Readiness writes a scalingSchedule to the MIG autoscaler with a deterministic schedule ID. Re-queue is a no-op, cancel cleanly removes the schedule, and originalMin/Max/Desired are restored on complete or cancel. ### Will ZopNight overwrite a MIG autoscaler I already configured? Only if you pick Replace. Adopt mode observes the existing autoscaler with source=adopted and never writes to GCP. Replace snapshots the prior config so Remove restores it byte-accurately.