Web Apps

Wed, 21 Oct 2026 17:55:00 +0000

My interactive front ends are Flutter apps, and on the web they are a set of static files: HTML, JavaScript and WebAssembly. So the container that runs one is just a web server, small and stateless. Heimdall’s web app is the example.

Concern	Choice
Framework	Flutter, built for the web
Build stage	Debian with a Flutter SDK pinned by version and checksum
Runtime	nginx, unprivileged, with a read-only file system
Settings	Compiled in at build time, once per environment
API	Its own origin’s `/api/`, routed to the API by Traefik
Health	`/healthz`
Checks	Analysis and tests, and generated code checked in GitHub Actions

The image

The build stage installs Flutter itself, rather than starting from a community Flutter image, so the exact SDK version is pinned and its download is checked against a SHA-256 checksum. It builds as a non-root user, and fetches packages with --enforce-lockfile, so the build uses exactly the versions the repository was tested with:

Nginx on Artur Rios Lab

Web Apps

The image