Fly.io

Deploy and manage applications on Fly.io using the flyctl CLI and Machines API. Use when asked to deploy an app, scale machines, check app status, view logs, manage secrets, create/destroy machines, set environment variables, run commands in a container, or manage Fly Postgres databases. Requires flyctl installed and authenticated via fly auth login.

Fly.io Skill

Fly.io is managed via the flyctl CLI (alias: fly) and the Machines REST API.

Auth

bash

fly auth login          # opens browser
fly auth token          # print current token
export FLY_API_TOKEN=$(fly auth token)

App Management

bash

fly apps list                          # list all apps
fly status -a <app-name>               # app health + machine states
fly info -a <app-name>                 # app details, IPs, regions
fly open -a <app-name>                 # open in browser

Deploy

bash

fly deploy                             # deploy from current dir (uses fly.toml)
fly deploy --image registry/image:tag  # deploy a specific image
fly deploy --remote-only               # build remotely (no local Docker needed)
fly deploy -a <app-name>               # target specific app

Logs

bash

fly logs -a <app-name>                 # live log stream
fly logs -a <app-name> --no-tail       # recent logs, no follow

Secrets

bash

fly secrets set MY_KEY=value -a <app-name>
fly secrets list -a <app-name>
fly secrets unset MY_KEY -a <app-name>

Scaling

bash

fly scale count 3 -a <app-name>                    # set machine count
fly scale memory 512 -a <app-name>                 # set RAM (MB)
fly scale vm shared-cpu-2x -a <app-name>           # change VM size
fly scale show -a <app-name>                        # current scale

Machines

bash

fly machine list -a <app-name>
fly machine status <machine-id> -a <app-name>
fly machine restart <machine-id> -a <app-name>
fly machine stop <machine-id> -a <app-name>
fly machine destroy <machine-id> -a <app-name>

Run a Command (one-off)

bash

fly ssh console -a <app-name>                      # interactive shell
fly ssh console -a <app-name> -C "ls -la /app"    # run single command

Postgres

bash

fly postgres create --name myapp-db                # create Postgres cluster
fly postgres connect -a myapp-db                   # psql shell
fly postgres attach myapp-db -a <app-name>         # attach DB to app (sets DATABASE_URL)

VM Sizes

shared-cpu-1x (256MB), shared-cpu-2x (512MB), performance-1x (2GB), performance-2x (4GB)

Regions

iad (Virginia), ord (Chicago), lax (LA), sea (Seattle), ams (Amsterdam), fra (Frankfurt), sin (Singapore), syd (Sydney)

Tips

• fly.toml is the app config — always check it before deploying
• fly deploy --strategy rolling for zero-downtime deploys
• Health checks in fly.toml under [checks] block