IMPORTED / COMPARISONS

RAILWAY VS FLY.IO: SECURITY COMPARISON

Railway and Fly.io are both popular deployment platforms for vibe-coded apps. But their security postures differ — especially around network isolation and compliance. We compared environment variables, network security, container isolation, and compliance side by side.

The bottom line

Fly.io has stronger compliance credentials with SOC 2 Type II, better network isolation via WireGuard and Firecracker microVMs, and more granular security controls. Railway is simpler to use but less mature on security certifications and network hardening.

Environment Variables

Feature Railway Fly.io Verdict
Secret storage Encrypted env vars in dashboard Encrypted secrets via flyctl Tie — both encrypt at rest
Secret injection Injected at build and runtime Injected at runtime only Fly.io slightly more secure
Secret visibility Visible in dashboard UI Write-only via CLI Fly.io harder to leak visually
Secret rotation Manual redeploy required Manual redeploy required Tie — both manual process

Network Security

Feature Railway Fly.io Verdict
Private networking Private networking between services WireGuard-based private networking Fly.io has stronger isolation
HTTPS/TLS Automatic HTTPS on all domains Automatic TLS termination Tie — both enforce TLS
IP allowlisting Not available Available via firewall rules Fly.io has IP restrictions
DDoS protection Basic protection included Anycast network with protection Fly.io has edge advantage

Container Security

Feature Railway Fly.io Verdict
Build process Nixpacks or Dockerfile Dockerfile required Railway auto-detects, Fly.io explicit
Base image control Limited with Nixpacks Full control via Dockerfile Fly.io gives more control
Runtime isolation Shared infrastructure Firecracker microVMs Fly.io has stronger isolation
Image scanning No built-in scanning No built-in scanning Tie — use external scanners

Compliance

Feature Railway Fly.io Verdict
SOC 2 Not yet certified SOC 2 Type II certified Fly.io ahead on compliance
Data residency US regions primarily Multiple global regions Fly.io more flexible
Audit logs Basic deploy logs Detailed audit trail Fly.io more comprehensive
Team permissions Role-based team access Role-based org access Tie — both support RBAC

Security risks unique to each

Railway-specific risks

  • Env vars visible in dashboard: Environment variables are readable in the Railway UI, increasing risk if dashboard credentials are compromised.
  • No IP allowlisting: Cannot restrict access to services by IP address, making network-level access control impossible.
  • Shared infrastructure concerns: Without Firecracker-level isolation, workloads share more infrastructure with other tenants.

Fly.io-specific risks

  • Configuration complexity: More config options mean more opportunities for misconfiguration — fly.toml, Dockerfile, and networking all need review.
  • Dockerfile security: Fly Machines security depends entirely on your Dockerfile. Bad base images or exposed ports create vulnerabilities.
  • WireGuard key management: Private networking keys need proper management. Lost or leaked keys compromise your entire private network.

How to secure either platform

  1. Never hardcode secrets in your codebase — use each platform’s secret management for all sensitive values
  2. Use minimal base images in Dockerfiles and scan them for known vulnerabilities before deploying
  3. Enable private networking between services — do not expose internal APIs to the public internet
  4. Set up monitoring and alerting for unusual traffic patterns or unauthorized access attempts
  5. Review deploy logs and audit trails regularly to detect configuration drift or unauthorized changes
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