Fly Machines API
Fly Machines REST API — create, start, stop, and manage individual Docker container instances (Machines) globally across Fly.io's edge network with microsecond boot times.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Firecracker microVM isolation provides hardware-level sandboxing. WireGuard private networking between Machines. SOC2 certified. Organization-level token scoping.
⚡ Reliability
Best When
Agents need fine-grained control over ephemeral compute — create/stop/destroy individual containers programmatically with global region placement.
Avoid When
You want simple app deployment — flyctl deploy handles typical web app deployments better than the Machines API directly.
Use Cases
- • Agents spinning up ephemeral compute containers on demand for isolated task execution
- • Horizontally scaling agent workers by programmatically creating and destroying Machines
- • Running agent workloads close to users by deploying Machines to specific geographic regions
- • Sandboxed code execution — each Machine is an isolated Firecracker microVM
- • Stateful machine management — stopping Machines between tasks and restarting on demand to save costs
Not For
- • Simple app deployment — use Fly Apps (flyctl deploy) for typical application deployments
- • Teams unfamiliar with Docker and containers — requires container and networking knowledge
- • Kubernetes-native workflows — Fly Machines is VM-based, not Kubernetes
Interface
Authentication
Fly API token from flyctl auth token command. Organization-scoped tokens for CI/CD. Passed as Authorization: Bearer header.
Pricing
Pay per second of compute. Stopped machines don't incur compute charges (only storage). Very cost-effective for agents with bursty compute needs.
Agent Metadata
Known Gotchas
- ⚠ Machines must be explicitly destroyed — stopped machines still incur disk storage costs
- ⚠ Machine startup time (200-500ms) means Machines API is not suitable for sub-100ms response requirements
- ⚠ Network configuration must be correct upfront — changing IPs or private networking after creation is complex
- ⚠ Process groups within a Machine require understanding of Fly's process model — not just single Docker CMD
- ⚠ Firecracker VMs have disk snapshot restore — first boot from snapshot is faster than full cold boot
Alternatives
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Scores are editorial opinions as of 2026-03-07.