An archive with your files and an optional app.json at the top.

{
  "name": "myapp",           // unit app-myapp.service
  "version": "v1.2.0",
  "kind": "binary",          // or "static"
  "exec": "myapp",           // linux binary in bundle
  "path": "/myapp",          // URL path on the site
  "health": "/healthz",      // checked after start
  "env": { "LOG_LEVEL": "info" }
}

The app gets ADDR, PORT, BASE_PATH and DATA_DIR. Listen on ADDR; serve under BASE_PATH.

Secrets: load a secrets.env in the deploy plan, never in the bundle.

Static site: "kind": "static", "static_dir": "dist".