Dev Specialisms:fly Deploy

Fly.io Deployment

Quick MVP deployment to fly.io with support for multiple languages, databases, GitHub integration, and production-ready configurations.

When to Use This Skill

Use this skill when you need to:

• Deploy a new application to fly.io quickly
• Migrate existing applications to fly.io
• Set up databases (Managed Postgres, SQLite with volumes, or Tigris object storage)
• Configure secrets and environment variables
• Add custom domains with SSL certificates
• Set up GitHub Actions for continuous deployment
• Create PR review apps (preview environments)
• Troubleshoot deployment or runtime issues
• Optimize fly.io configurations for cost and performance

Quick Start

New Application

# From your app directory
fly launch

# Follow interactive prompts:
# - Choose app name
# - Select region
# - Configure resources
# - Deploy immediately or create config only

Existing Application

# Deploy app with existing fly.toml
fly deploy

# Build on fly.io servers (recommended for CI/CD)
fly deploy --remote-only

Workflow Decision Tree

1. Choose Your Starting Point

New App (No fly.toml) → See: Deploying New Applications

Existing fly.io App → See: Deploying Existing Applications

Migrating from Another Platform → See: references/deployment-workflow.md + Language-specific guides

2. Choose Your Language/Framework

Navigate to the appropriate language guide:

JavaScript/Node.js:

• Next.js → references/languages/javascript.md#nextjs
• Express → references/languages/javascript.md#express
• RedwoodJS → references/languages/javascript.md#redwoodjs

Python:

• FastAPI → references/languages/python.md#fastapi
• Django → references/languages/python.md#django
• Flask → references/languages/python.md#flask

Rust:

• Axum → references/languages/rust.md#axum
• Rocket → references/languages/rust.md#rocket

Generic Dockerfile: → See: references/deployment-workflow.md

Each language guide includes:

• Optimized Dockerfiles (see also: assets/dockerfiles/)
• fly.toml configuration examples
• Framework-specific best practices
• Common issues and solutions

3. Add Data Persistence (Optional)

Choose based on your needs:

Managed Postgres (Recommended for production SQL databases) → See: references/data-persistence.md#managed-postgres → Script: scripts/init_postgres.sh

Volumes (For SQLite, file uploads, or local storage) → See: references/data-persistence.md#fly-volumes

Tigris Object Storage (For media files, user uploads, S3-compatible) → See: references/data-persistence.md#tigris-object-storage → Script: scripts/setup_tigris.sh

External Database (Supabase, PlanetScale, Neon, etc.) → See: references/data-persistence.md#external-databases

4. Configure Secrets

→ See: references/secrets-and-env.md

# Set secrets
fly secrets set DATABASE_URL=postgres://...
fly secrets set API_KEY=abc123

# Generate random secrets
fly secrets set SECRET_KEY=$(openssl rand -hex 32)

5. Add Custom Domain (Optional)

→ See: references/domains-and-networking.md

# Add custom domain
fly certs add example.com

# View DNS instructions
fly certs show example.com

6. Set Up CI/CD (Optional)

GitHub Actions Deployment: → See: references/github-integration.md → Template: assets/workflows/deploy.yml

PR Review Apps: → See: references/github-integration.md#review-apps → Template: assets/workflows/review-apps.yml → Script: scripts/setup_review_apps.sh

Deploying New Applications

Step 1: Prepare Your Application

Ensure your app has:

1. Dockerfile or package.json/requirements.txt (for buildpacks)
2. Health endpoint (e.g., /health returning 200 OK)
3. Port configuration reading from PORT environment variable
4. Bind to 0.0.0.0 (not localhost or 127.0.0.1)

Example Dockerfiles available in: assets/dockerfiles/

• nextjs.Dockerfile
• express.Dockerfile
• fastapi.Dockerfile
• axum.Dockerfile
• rocket.Dockerfile

Step 2: Initialize fly.io App

fly launch

Interactive prompts will:

• Detect your app type
• Suggest a name
• Choose a region
• Create fly.toml
• Optionally deploy immediately

Useful flags:

# Skip deployment, just create config
fly launch --no-deploy

# Specify app name
fly launch --name my-app

# Choose region
fly launch --region ord  # Chicago

Step 3: Configure fly.toml

Review and adjust fly.toml:

app = "my-app"
primary_region = "ord"

[build]
  dockerfile = "Dockerfile"

[env]
  PORT = "8080"

[http_service]
  internal_port = 8080
  force_https = true
  auto_stop_machines = "stop"
  auto_start_machines = true
  min_machines_running = 0  # Scale to zero for cost savings

  [[http_service.checks]]
    grace_period = "10s"
    interval = "30s"
    path = "/health"

[[vm]]
  memory = "256mb"
  cpus = 1

→ For complete fly.toml reference: references/deployment-workflow.md

Step 4: Deploy

fly deploy

Your app will be available at: https://my-app.fly.dev

Deploying Existing Applications

For apps with existing fly.toml:

# Standard deployment
fly deploy

# Remote build (recommended for CI/CD)
fly deploy --remote-only

# Specific deployment strategy
fly deploy --strategy rolling  # Zero downtime (default)
fly deploy --strategy immediate  # Faster, brief downtime

Common Tasks

Adding a Database

Managed Postgres (Recommended):

# Using the provided script
./scripts/init_postgres.sh --app my-app

# Or manually
fly postgres create --name my-app-db
fly postgres attach my-app-db

Tigris Object Storage:

# Using the provided script
./scripts/setup_tigris.sh --app my-app

# Or manually
fly storage create

→ See: references/data-persistence.md

Managing Secrets

# Set secrets
fly secrets set DATABASE_URL=postgres://...
fly secrets set API_KEY=secret123

# List secrets (names only)
fly secrets list

# Remove secrets
fly secrets unset API_KEY

→ See: references/secrets-and-env.md

Setting Up Review Apps

# Using the provided script
./scripts/setup_review_apps.sh --org personal --region ord

# Or copy template manually
cp assets/workflows/review-apps.yml .github/workflows/

→ See: references/github-integration.md#review-apps

Adding Custom Domain

# Add domain
fly certs add example.com

# Get your app's IP addresses
fly ips list

# Configure DNS (A and AAAA records)
# Then verify
fly certs show example.com

→ See: references/domains-and-networking.md

Scaling

# Scale memory
fly scale memory 512

# Scale machine size
fly scale vm shared-cpu-2x

# Scale instance count
fly scale count 3

# Scale across regions
fly scale count 2 --region ord,iad

→ See: references/deployment-workflow.md#scaling

Troubleshooting

Common Issues

App won't start:

# Check logs
fly logs

# Verify port configuration
# App must listen on PORT env var and bind to 0.0.0.0

Health checks failing:

# Test health endpoint
fly ssh console -C "curl http://localhost:8080/health"

# Adjust grace period in fly.toml if needed

Database connection errors:

# Verify DATABASE_URL is set
fly secrets list

# Test from within app
fly ssh console
echo $DATABASE_URL

Deployment slow or timing out:

# Use remote builder
fly deploy --remote-only

# Check build cache
fly deploy --no-cache

→ For comprehensive troubleshooting: references/troubleshooting.md

Debugging Commands

# View app status
fly status

# Stream logs
fly logs

# SSH into running machine
fly ssh console

# List machines
fly machine list

# View deployments
fly releases

# Check health checks
fly checks list

Reference Documentation

Core Guides

• Deployment Workflow - fly.toml configuration, deployment strategies, scaling
• Data Persistence - Postgres, volumes, Tigris, external databases
• Secrets Management - Environment variables, secret handling, security
• GitHub Integration - GitHub Actions, review apps, CI/CD
• Custom Domains - DNS setup, SSL certificates, networking
• Troubleshooting - Common issues, debugging techniques, solutions

Language-Specific Guides

• JavaScript/Node.js - Next.js, Express, RedwoodJS
• Python - FastAPI, Django, Flask
• Rust - Axum, Rocket

Bundled Resources

Scripts (scripts/)

Automation scripts for common tasks:

• setup_review_apps.sh - Generate GitHub Actions workflow for PR review apps
• init_postgres.sh - Create and attach Managed Postgres database
• setup_tigris.sh - Configure Tigris object storage bucket

All scripts include help text. Run with --help or without arguments for usage.

Dockerfile Templates (assets/dockerfiles/)

Production-ready Dockerfiles for each framework:

• nextjs.Dockerfile - Next.js with standalone output (minimal image)
• express.Dockerfile - Express.js with multi-stage build
• fastapi.Dockerfile - FastAPI with uvicorn
• axum.Dockerfile - Axum with optimized Rust build
• rocket.Dockerfile - Rocket with multi-stage build

Copy and customize for your app.

GitHub Actions Workflows (assets/workflows/)

Ready-to-use workflow templates:

• deploy.yml - Basic deployment on push to main
• review-apps.yml - PR review apps with automatic cleanup
• test-and-deploy.yml - Run tests before deploying

Copy to .github/workflows/ and customize.

Best Practices

1. Always use health checks - Ensures reliable deployments
2. Start with minimal resources - Scale up based on actual usage
3. Use Managed Postgres for production - Don't run unmanaged databases
4. Set secrets properly - Never commit secrets to git
5. Use remote builds for CI/CD - fly deploy --remote-only
6. Test locally first - Build and test Docker images locally
7. Monitor logs regularly - fly logs helps catch issues early
8. Use review apps - Test changes before merging
9. Configure graceful shutdown - Handle SIGTERM properly
10. Keep dependencies updated - Security and performance

Quick Reference

# Essential commands
fly launch              # Create new app
fly deploy             # Deploy app
fly status             # Check app status
fly logs               # View logs
fly ssh console        # SSH into machine

# Database
fly postgres create    # Create database
fly postgres attach    # Attach to app
fly storage create     # Create Tigris bucket

# Configuration
fly secrets set KEY=value    # Set secret
fly secrets list            # List secrets
fly scale memory 512        # Scale memory
fly scale count 3           # Scale instances

# Domains
fly certs add example.com   # Add domain
fly certs show example.com  # Check certificate
fly ips list               # Get IP addresses

# Troubleshooting
fly logs                    # Stream logs
fly ssh console            # Access machine
fly checks list            # View health checks
fly releases               # View deployments

Getting Help

• Documentation: https://fly.io/docs/
• Community Forum: https://community.fly.io/
• Status Page: https://status.flyio.net/
• This Skill: Check references/troubleshooting.md for common issues

Note: fly.io changes frequently. This skill is based on documentation current as of January 2026. If commands or features have changed, consult the official fly.io documentation at https://fly.io/docs/