Deploy to Fly.io

Fly.io deploys Docker containers to lightweight Firecracker VMs near your users. The free tier auto-scales to zero when idle, which makes it the cheapest “running production” deploy for low-traffic apps. Fly doesn’t host MongoDB itself — pair with Atlas, or run a Mongo container on a separate internal-only Fly app.

Quick reference


Cost (small app)	$0-5/mo (autostops when idle) + Atlas
Managed Mongo?	No — external (Atlas recommended)
Cold start?	~1s wake from autostop
TLS	Automatic on `*.fly.dev` + custom domains
Multi-region	Yes (one of Fly’s strengths)

Prerequisites

flyctl installed (brew install flyctl on macOS).
A Fly account (fly auth signup / fly auth login).
A MongoDB Atlas cluster (or another reachable Mongo).

Deploy

Initialise.
Terminal window
```
cd your-davepi-project
fly launch
```
fly launch auto-detects the Node project, generates a fly.toml, and offers to deploy. Accept the defaults; the first deploy will fail because env vars aren’t set yet — that’s fine.

Set secrets.

fly secrets set \
  MONGO_URI='mongodb+srv://user:pass@cluster.mongodb.net/davepi' \
  TOKEN_KEY="$(node -e 'console.log(require(\"crypto\").randomBytes(48).toString(\"hex\"))')" \
  CORS_ORIGINS='https://your-frontend.example.com'

Edit fly.toml. Pin PORT and the health check:

[env]
  NODE_ENV = "production"
  PORT     = "8080"

[http_service]
  internal_port = 8080
  force_https   = true
  auto_stop_machines  = true
  auto_start_machines = true
  min_machines_running = 0  # set to 1 to keep one warm

  [[http_service.checks]]
    method   = "get"
    path     = "/healthz"
    interval = "30s"
    timeout  = "5s"

Deploy.
Terminal window
```
fly deploy --remote-only
```
The deploy logs show the build + boot. When /healthz passes, traffic switches. App URL is https://<app-name>.fly.dev.
Verify.
Terminal window
```
curl https://<app-name>.fly.dev/healthz
```

The repo’s shipped GitHub Actions deploy workflow targets Fly.io by default — once FLY_API_TOKEN is set as a repo secret, every push to main deploys automatically (gated behind the production environment for manual approval).

Custom domain + TLS

fly certs add api.example.com
# DNS: CNAME api -> <app-name>.fly.dev (or A/AAAA records Fly suggests)
fly certs show api.example.com   # watches the cert provision

Backups

Atlas free tier (M0) doesn’t include continuous backup; M10 does. For free tier, run mongodump from a Fly scheduled machine (fly machine run with --schedule) and upload to a bucket.

Scaling

Vertical: fly scale vm shared-cpu-1x --memory 512 → performance-1x etc. as needed.
Horizontal: fly scale count 3 — three machines load- balanced. With auto_stop_machines = true, idle replicas stop automatically.
Multi-region: fly regions add fra sin adds Frankfurt and Singapore. Fly’s anycast router sends traffic to the nearest live machine. Mongo (Atlas) becomes the latency- bottleneck for far-from-DB regions; pair with Atlas’s global cluster for matching geography.

Observability

Logs: fly logs streams stdout; Fly retains 5 days. Ship to external collectors via Fly’s Datadog / Better Stack integrations.
Metrics: Fly’s built-in Grafana provides VM-level metrics for free. App-level metrics via METRICS_ENABLED=true + scrape through Fly’s internal network with Grafana Cloud.