fly-machines-and-apps

fly-machines-and-apps is a skill for Claude Code from jsgerman-oss/blackrim-nimbus-skills. It costs 75 tokens per session (2,334 once invoked), scanned A, original, MIT.

A guide to running applications on Fly.io using Machines, which are small Firecracker virtual machines. It covers machine sizing, regions, automatic starting and stopping, routing, deployments, and rollbacks.

In plain words
What is it for?
Use it to design or operate Fly Machines and Apps, configure fly.toml services, implement scale-to-zero, plan multi-region deployments, or diagnose release failures.
Why use it?
It helps choose an appropriate runtime setup and avoid mistakes in scaling, regional placement, deployment strategy, or Fly configuration.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the cloud-fly plugin — 5 skills, 1 command, 2 agents shipped together

Good fit Use it to design or operate Fly Machines and Apps, configure fly.toml services, implement scale-to-zero, plan multi-region deployments, or diagnose release failures.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/jsgerman-oss/blackrim-nimbus-skills/fly-machines-and-apps
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add jsgerman-oss/blackrim-nimbus-skills --skill fly-machines-and-apps
Clone the repo
git clone --depth 1 https://github.com/jsgerman-oss/blackrim-nimbus-skills

Made for: Claude Code.

Or install cloud-fly, the plugin that ships this one along with the rest of its 5 skills, 1 command, 2 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for fly-machines-and-apps

README.md
[![agentmods](https://agentmods.dev/badge/skills/jsgerman-oss/blackrim-nimbus-skills/fly-machines-and-apps/github.svg)](https://agentmods.dev/skills/jsgerman-oss/blackrim-nimbus-skills/fly-machines-and-apps)
Your own site
<a href="https://agentmods.dev/skills/jsgerman-oss/blackrim-nimbus-skills/fly-machines-and-apps"><img src="https://agentmods.dev/badge/skills/jsgerman-oss/blackrim-nimbus-skills/fly-machines-and-apps/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for fly-machines-and-apps

Your own site · 80×15
<a href="https://agentmods.dev/skills/jsgerman-oss/blackrim-nimbus-skills/fly-machines-and-apps"><img src="https://agentmods.dev/badge/skills/jsgerman-oss/blackrim-nimbus-skills/fly-machines-and-apps.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,334 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00075 $0.02334
Opus 5 $0.00037 $0.01167
Sonnet 5 $0.00015 $0.00467
Haiku 4.5 $0.00007 $0.00233

Measured 12d ago against content hash dcbf79050507, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

fly-machines-and-apps scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

cloud-fly/skills/fly-machines-and-apps/SKILL.md · 160 lines

How it starts

The opening of the file, as written. The whole thing — 160 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Fly Machines and Apps

When to use

  • Choosing a machine size for a new workload (CPU, memory, GPU).
  • Configuring auto-start / auto-stop for scale-to-zero behavior.
  • Designing a multi-region placement strategy with latency budgets.
  • Reviewing or writing a fly.toml services block.
  • Deciding between immediate, rolling, blue-green, or canary deploys.
  • Debugging a release or rollback failure.
  • Using fly-replay to route requests to a specific region or machine.

Core concepts

Machines — the primary primitive

A Fly Machine is a Firecracker microVM. It is the unit of compute on Fly. Unlike container schedulers, Fly runs one Machine per Firecracker VM — there is no pod / task abstraction layered on top. Machines start in milliseconds (not seconds), and Fly bills by the millisecond of runtime.

A Fly App is a logical grouping of Machines that share a name, network identity, and fly.toml configuration. An App can contain Machines of different sizes in different regions — they share nothing except the App namespace and the private 6PN network.

Auto-start / auto-stop (scale-to-zero)

auto_stop_machines = "stop" halts a Machine when it has no active connections. auto_start_machines = true starts it when an incoming request arrives. The Fly Proxy holds the inbound connection while the Machine boots (typically 300–800 ms for a pre-built image). Design accordingly:

  • Idempotent request handling is mandatory. The proxy may route a request to a machine mid-boot; ensure your startup path completes before accepting traffic.
  • Health checks gate readiness. Define [[services.http_checks]] or TCP checks so Fly Proxy only routes after the Machine is truly ready.
  • Cold-start budget. For user-facing latency budgets under 1 s, test cold-start with a real image, not docker pull time. Images pre-pulled from Fly's depot (layer caching) start faster.
  • min_machines_running. Set to 1 if you cannot tolerate cold starts. The cost of one stopped machine is zero; the cost of one min_machines_running = 1 machine is the per-hour rate.

Read the full file on GitHub · 160 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 160 lines · 75 tokens per session scan A dcbf79050507

Subscribe to this mod's changes

fly-machines-and-apps is a skill published in the GitHub repository jsgerman-oss/blackrim-nimbus-skills (8 stars, last pushed 26d ago), licensed MIT. It adds 75 tokens to every session and 2,334 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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