Does Ruby on Rails Work With Fly.io?
Ruby on Rails runs excellently on Fly.io with first-class support, containerization, and zero major friction points.
Quick Facts
How Ruby on Rails Works With Fly.io
Fly.io provides native Rails support through the `flyctl` CLI, which automates Dockerfile generation and deploys your app to their global infrastructure. The platform handles scaling, SSL certificates, and health checks automatically. Rails apps deploy as Docker containers across Fly's edge locations, letting users connect to the geographically closest instance. The developer experience is streamlined: `fly launch` creates a Fly.toml config, sets up a Postgres database on Fly if needed, and configures environment variables. You get automatic HTTPS, rolling deployments, and built-in monitoring without additional setup. The only consideration is that Fly uses a "bring your own database" model—you can use Fly Postgres (managed) or connect to external databases. Rails' asset pipeline works seamlessly, and Active Job integrates cleanly with background job runners. Fly's pricing model (pay-as-you-go with generous free tier) suits Rails apps well, and the platform's focus on performance and edge deployment complements Rails' full-stack capabilities.
Best Use Cases
Deploy a Rails App to Fly.io
curl -L https://fly.io/install.sh | sh# 1. Create new Rails app or use existing one
rails new myapp
cd myapp
# 2. Initialize Fly deployment
fly launch
# Answer prompts: app name, region, create Postgres (yes recommended)
# 3. Deploy to Fly
fly deploy
# 4. View logs and open app
fly logs
fly open
# 5. Set environment secrets
fly secrets set RAILS_MASTER_KEY=$(cat config/master.key)
fly secrets set SECRET_KEY_BASE=$(rails secret)Known Issues & Gotchas
Ephemeral filesystem means uploaded files disappear after app restart
Fix: Use S3 or Tigris Object Storage instead of local /public directory. Update Active Storage config to use external storage adapter.
Database connections can timeout during deploys if not properly configured
Fix: Set DATABASE_URL in secrets, enable connection pooling, and use Fly's built-in database scaling features.
Cold boots on rarely-used regions may take 5-10 seconds
Fix: Use Fly's autoscaling and min_machines_running config to keep instances warm in key regions.
Environment-specific secrets must be managed through fly secrets, not .env files
Fix: Use `fly secrets set KEY=value` and never commit secrets; leverage Rails' encrypted credentials alongside Fly secrets.
Alternatives
- •Heroku + Ruby on Rails: Simpler setup, higher cost, less global edge presence
- •AWS Elastic Beanstalk + Rails: More control, steeper learning curve, traditional availability zones
- •DigitalOcean App Platform + Rails: Mid-tier pricing, straightforward deployment, fewer regions
Resources
Related Compatibility Guides
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