Building a security posture scanner with Next.js and Python

I wanted to learn cloud security the way it actually sticks: by building something real. So I built PostureGuard, a web application that scans a domain and returns a security posture report covering TLS, HTTP security headers and open ports, with a 0-100 score and an A-F grade. This post walks through the architecture and the decisions I found most interesting. Update: Phase 1 is done. PostureGuard now runs on Azure Container Apps and is live at app.samdossou.com . The write-up is the next post in this series. The shape of the system PostureGuard has three moving parts: A Next.js web app (App Router, TypeScript) where users sign up, add a domain, and request scans. A PostgreSQL database that stores users, domains and scans. A Python worker that runs the actual scans in the background. The web app never runs a scan itself. When a user clicks "Scan", the app just inserts a row into a scans table with the status queued and returns immediately. The worker picks the job up a moment later. This keeps the request fast and the two halves of the system decoupled. Using PostgreSQL as a job queue The part I like most is that there is no separate message broker. The scans table doubles as the queue. The worker claims one job at a time with a single query: SELECT s . id , d . name FROM scans s JOIN domains d ON d . id = s . domain_id WHERE s . status = 'queued' ORDER BY s . requested_at FOR UPDATE OF s SKIP LOCKED LIMIT 1 FOR UPDATE locks the row so no one else can grab it, and SKIP LOCKED tells other workers to ignore locked rows and move on to the next job. That means I can run several workers in parallel and they will never process the same scan twice, without any extra infrastructure. For a project at this scale, a table plus SKIP LOCKED is simpler and more than enough. The scanners The worker runs three checks, all built on the Python standard library to keep dependencies light: TLS: it opens a TLS connection, reads the certificate expiry and the negotiated protocol version