Fly Io

Fly.io

Global edge deployment platform running applications in Firecracker micro-VMs close to users.

Quick Start

# Install flyctl
curl -L https://fly.io/install.sh | sh

# Or on macOS
brew install flyctl

# Login
fly auth login

# Launch app (creates fly.toml)
fly launch

# Deploy
fly deploy

Project Setup

fly.toml

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

[build]
  dockerfile = "Dockerfile"

[http_service]
  internal_port = 3000
  force_https = true
  auto_stop_machines = true
  auto_start_machines = true
  min_machines_running = 1

  [http_service.concurrency]
    type = "requests"
    hard_limit = 250
    soft_limit = 200

[[vm]]
  cpu_kind = "shared"
  cpus = 1
  memory_mb = 256

Basic Dockerfile

FROM node:20-alpine

WORKDIR /app

COPY package*.json ./
RUN npm ci --only=production

COPY . .
RUN npm run build

EXPOSE 3000

CMD ["node", "dist/index.js"]

Deployment

Deploy from Git

# First deploy creates app
fly launch

# Subsequent deploys
fly deploy

# Deploy specific Dockerfile
fly deploy --dockerfile Dockerfile.prod

# Deploy with build args
fly deploy --build-arg API_KEY=$API_KEY

Deploy Strategies

[deploy]
  strategy = "rolling"  # default
  # strategy = "immediate"
  # strategy = "canary"
  # strategy = "bluegreen"

Regions

Multi-Region Deployment

# Add regions
fly regions add ams lhr syd

# List regions
fly regions list

# Remove region
fly regions remove syd

Region Configuration

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

# Scale to multiple regions
[[vm]]
  memory = "256mb"
  cpu_kind = "shared"
  cpus = 1

  [vm.processes]
    web = 2  # 2 machines per region

Available Regions

Secrets & Environment

Secrets (Encrypted)

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

# List secrets
fly secrets list

# Unset secret
fly secrets unset API_KEY

Environment Variables

# fly.toml
[env]
  NODE_ENV = "production"
  LOG_LEVEL = "info"

Per-Region Environment

[[env]]
  NODE_ENV = "production"

  [[env.region]]
    region = "ord"
    CDN_URL = "https://us-cdn.example.com"

  [[env.region]]
    region = "ams"
    CDN_URL = "https://eu-cdn.example.com"

Scaling

Machine Scaling

# Scale up
fly scale count 3

# Scale per region
fly scale count 2 --region ord
fly scale count 1 --region ams

# Scale VM size
fly scale vm shared-cpu-1x
fly scale vm dedicated-cpu-1x
fly scale memory 512

Auto-scaling

[http_service]
  auto_stop_machines = true
  auto_start_machines = true
  min_machines_running = 1
  max_machines_running = 10

  [http_service.concurrency]
    type = "requests"
    soft_limit = 100
    hard_limit = 250

Databases

Postgres

# Create Postgres cluster
fly postgres create

# Attach to app
fly postgres attach my-postgres-db

# Connect
fly postgres connect -a my-postgres-db

# Proxy to local
fly proxy 5432 -a my-postgres-db

Redis

# Create Redis
fly redis create

# Get connection string
fly redis status my-redis

LiteFS (SQLite)

# Create LiteFS cluster
fly apps create my-app-litefs

# Configure in fly.toml
[mounts]
  source = "litefs"
  destination = "/var/lib/litefs"

Volumes (Persistent Storage)

# Create volume
fly volumes create mydata --size 1 --region ord

# List volumes
fly volumes list

# Destroy volume
fly volumes destroy vol_xxx

# fly.toml
[mounts]
  source = "mydata"
  destination = "/data"

Networking

Custom Domains

# Add domain
fly certs add example.com

# Check certificate status
fly certs show example.com

Private Networking

# Internal services communicate via .internal DNS
# api.internal:3000

Static IPs

# Allocate IPv4 (paid)
fly ips allocate-v4

# List IPs
fly ips list

Health Checks

[http_service]
  internal_port = 3000

  [[http_service.checks]]
    grace_period = "5s"
    interval = "10s"
    timeout = "2s"
    path = "/health"
    method = "GET"
    protocol = "http"

Processes

Multiple Processes

[processes]
  web = "node dist/server.js"
  worker = "node dist/worker.js"

[[http_service]]
  processes = ["web"]
  internal_port = 3000

[[services]]
  processes = ["worker"]
  internal_port = 0

Background Workers

[processes]
  worker = "node dist/worker.js"

[[services]]
  processes = ["worker"]
  internal_port = 0
  auto_stop_machines = false

Node.js Configuration

Optimized Dockerfile

FROM node:20-alpine AS builder

WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build
RUN npm prune --production

FROM node:20-alpine

WORKDIR /app
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
COPY --from=builder /app/package.json ./

ENV NODE_ENV=production
USER node

CMD ["node", "dist/index.js"]

Next.js

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

[build]
  dockerfile = "Dockerfile"

[http_service]
  internal_port = 3000
  force_https = true
  auto_stop_machines = true
  auto_start_machines = true

[[vm]]
  memory = "512mb"
  cpu_kind = "shared"
  cpus = 1

CLI Commands

# App management
fly apps create my-app
fly apps list
fly apps destroy my-app

# Deployment
fly deploy
fly deploy --strategy immediate
fly status

# Logs
fly logs
fly logs -a my-app

# SSH
fly ssh console
fly ssh console -C "node -v"

# Monitoring
fly status
fly dashboard

# Scaling
fly scale show
fly scale count 3
fly scale memory 512

# Regions
fly regions list
fly regions add ord ams

# Secrets
fly secrets set KEY=value
fly secrets list

See references/configuration.md for complete fly.toml options.