App Properties

The $app.* namespace exposes platform-injected properties of the deployed app itself. These are resolved at deploy time by whichever provider is running the app, so a Launchfile can reference its own public URL without hardcoding environment-specific values.

The values are determined by the provider's routing strategy at deploy time. A Cloudflare Tunnel deployment might resolve $app.url to https://myapp.example.com; a local development provider might resolve it to http://myapp.lvh.me:10001; a Kubernetes deployment behind an Ingress might resolve it to https://myapp.k8s.internal. The Launchfile stays the same.

The standard set above is the portable vocabulary every provider must support. Providers MAY expose additional $app.* properties (e.g. $app.region, $app.deployment_id) as platform-specific extensions; portable Launchfiles should use only the standard set. Unknown $app.* properties resolve to empty string, matching the behavior of unknown resource properties (see L-4).

$app.url differs from $components.<this>.url in two ways. First, it gives the public URL — the address external users reach the app on — not the internal component port. Second, it works in single-component mode where there is no component name to reference. Use $app.url for public-facing values (auth callback URLs, webhook registration, public-facing email links) and $components.<name>.url for internal cross-component wiring.

Similarly, $app.port is the allocated external port that the platform exposes; provides[].port is the container port the component binds inside its sandbox. They can differ — a component might bind 3000 while the platform exposes 10001.

Example use:

env:
  PUBLIC_URL: $app.url                # Drupal, BookStack, Mealie, Firefly III
  BETTER_AUTH_URL: $app.url           # better-auth callback base
  OAUTH_REDIRECT_URI: "${app.url}/oauth/callback"
  WEBHOOK_URL: "${app.url}/webhooks/incoming"