Agent skill
flyio-cost-tuning
Optimize Fly.io costs with auto-stop/suspend, right-sizing VMs, volume management, and monitoring spend across apps and regions. Trigger: "fly.io costs", "fly.io pricing", "fly.io billing", "reduce fly.io spend".
Install this agent skill to your Project
npx add-skill https://github.com/jeremylongshore/claude-code-plugins-plus-skills/tree/main/plugins/saas-packs/flyio-pack/skills/flyio-cost-tuning
SKILL.md
Fly.io Cost Tuning
Overview
Fly.io charges per-second for running machines plus storage. Key levers: auto-stop idle machines, suspend instead of stop, right-size VMs, and clean up unused volumes.
Pricing Quick Reference
| Resource | Free Tier | Cost |
|---|---|---|
| shared-cpu-1x (256mb) | 3 VMs free | ~$1.94/month each |
| shared-cpu-1x (512mb) | included | ~$3.88/month |
| shared-cpu-2x (1gb) | - | ~$11.62/month |
| Volumes | 3GB free | $0.15/GB/month |
| Bandwidth | 100GB free | $0.02/GB after |
| IPv4 | 1 free per org | $2/month each |
Instructions
Strategy 1: Auto-Stop Idle Machines
# fly.toml — stop machines when no traffic
[http_service]
auto_stop_machines = "stop" # Full stop (cheapest, ~5s cold start)
auto_start_machines = true
min_machines_running = 0 # Allow all machines to stop
# Use min_machines_running = 1 only for production apps
Strategy 2: Suspend for Faster Resume
# Suspend keeps memory state — resumes in ~100ms but costs ~$0.50/month
[http_service]
auto_stop_machines = "suspend"
Strategy 3: Audit and Clean Up
# List all apps and their machine counts
fly apps list
# Find idle/stopped machines
fly machine list -a my-app --json | jq '.[] | select(.state != "started") | {id, state, region}'
# Destroy unused apps
fly apps destroy old-app --yes
# List and delete orphaned volumes
fly volumes list -a my-app
fly volumes destroy vol_xxx
Strategy 4: Right-Size VMs
# Check memory usage to see if oversized
fly ssh console -a my-app -C "cat /proc/meminfo | head -3"
# Downgrade if using <50% of allocated memory
fly scale vm shared-cpu-1x --memory 256 -a my-app
Cost Monitoring
# Check current month's usage
fly billing # Shows org-level billing
# Estimate per-app cost
fly scale show -a my-app # See VM count and size
Resources
Next Steps
For architecture design, see flyio-reference-architecture.
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