Flyio hello world

Fly.io Hello World

Overview

Deploy a minimal app to Fly.io using fly launch. Fly.io runs Docker containers on Firecracker microVMs across 30+ regions worldwide. Two paths: flyctl CLI (simple) or Machines API (programmatic).

Instructions

Step 1: Launch with flyctl

# Create a new directory with a Dockerfile
mkdir fly-hello && cd fly-hello

cat > Dockerfile << 'EOF'
FROM node:20-alpine
WORKDIR /app
COPY server.js .
EXPOSE 3000
CMD ["node", "server.js"]
EOF

cat > server.js << 'EOF'
const http = require('http');
const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({
    message: 'Hello from Fly.io!',
    region: process.env.FLY_REGION,
    app: process.env.FLY_APP_NAME,
  }));
});
server.listen(3000, () => console.log('Listening on :3000'));
EOF

# Launch — creates app, generates fly.toml, deploys
fly launch --name hello-fly --region iad --now

Step 2: Verify Deployment

# Check status
fly status

# Open in browser
fly open

# View logs
fly logs

# Test with cURL
curl https://hello-fly.fly.dev/
# {"message":"Hello from Fly.io!","region":"iad","app":"hello-fly"}

Step 3: Deploy via Machines API

const FLY_API = 'https://api.machines.dev';
const headers = {
  'Authorization': `Bearer ${process.env.FLY_API_TOKEN}`,
  'Content-Type': 'application/json',
};

// Create an app
const app = await fetch(`${FLY_API}/v1/apps`, {
  method: 'POST',
  headers,
  body: JSON.stringify({
    app_name: 'hello-api',
    org_slug: 'personal',
  }),
}).then(r => r.json());

// Create a machine in the app
const machine = await fetch(`${FLY_API}/v1/apps/hello-api/machines`, {
  method: 'POST',
  headers,
  body: JSON.stringify({
    region: 'iad',
    config: {
      image: 'nginx:alpine',
      services: [{
        ports: [{ port: 443, handlers: ['tls', 'http'] }],
        protocol: 'tcp',
        internal_port: 80,
      }],
      guest: { cpu_kind: 'shared', cpus: 1, memory_mb: 256 },
    },
  }),
}).then(r => r.json());

console.log(`Machine ${machine.id} created in ${machine.region}`);

Output

Machine e784079f004d86 created in iad
App URL: https://hello-api.fly.dev

Error Handling

Error	Cause	Solution
No machines in group	App exists but no machines	Run fly deploy or create via API
Could not find image	Docker build failed	Check Dockerfile, run docker build . locally
Region not available	Invalid region code	Use fly platform regions to list valid codes
Insufficient resources	Org quota reached	Check fly orgs show or upgrade plan

Resources

• Fly Launch
• Deploy an App
• Machines API

Next Steps

Proceed to flyio-local-dev-loop for development workflow setup.