phone_preview

Opens a Rails app running on your Mac on a phone, through an ngrok tunnel at a fixed public address.

phone_preview starts the app's server and an ngrok tunnel on one port, prints the public address and a QR code of it to scan with the phone's camera, and in development makes emailed links use that address so they open on the phone.

• An ngrok account with a reserved domain for the app, such as app-dev.ngrok.app, and the ngrok command signed in to that account.
• overmind, which runs the server and the tunnel together.

Add the gem to the app's development group:

group :development do
  gem "phone_preview"
end

Give the app a bin/phone that names its public address and runs the gem's command:

#!/usr/bin/env sh

export PUBLIC_BASE_URL="${PUBLIC_BASE_URL:-https://app-dev.ngrok.app}"

exec bundle exec phone_preview "$@"

Run bin/phone, or up phone from symphony, which picks the first free port. Open the printed address on the phone, or scan the QR code.

With no PORT set, the server starts on port 3000.

Before starting anything, phone_preview stops with a message when ngrok is not installed, when ngrok is not signed in to an account, when the port is already in use, or when another running tunnel already holds the public address. If the tunnel stops while the app runs, the terminal says the phone can no longer reach the app.

When PUBLIC_BASE_URL is set in development, emailed links use it over https with no port. With it unset, or outside development, emailed links keep the app's own action_mailer.default_url_options.

Live connections through Action Cable need no setting, because Rails accepts a connection whose origin matches the address the request arrives on.