Preview environments per PR for under 10 euros: my exact setup

Felix W. told me to raise prices, so instead I cut costs. Every PR gets a full preview: app + Postgres + seeded demo data, on a wildcard subdomain, dies when the PR closes.

How: one Coolify project, Docker Compose template, Traefik wildcard cert, database seeded from a 90MB sanitized dump (not production, never production). PRs under 5 changed files share a pool of two warm standbys. Total extra cost: one small VPS at 6 euros plus storage. The seeding takes 40 seconds and everyone complains about the 40 seconds.

Worth it? Support tickets with "works on staging" screenshots dropped by half. Customers test the actual preview link now.

The 40-second seed complaint is how you know it works. What sanitizes the dump? This is where everyone gets lazy.

Deterministic scrubber in CI: emails to fake domains, names replaced, payment tokens nuked, plus a verify step that greps the dump for production patterns and fails the build. Lazy is not available, the pipeline refuses.

Tabstash previews are extension builds, different shape, same lesson: the preview has to be one click from the PR or nobody uses it. Ours posts the install link as a PR comment. Usage went from 10% to 90%.

Steal-worthy: warm standbys for small PRs. Our previews boot cold and the 3-minute wait kills the habit. How do you route a PR to a warm box?

Label check in CI: docs-only or under-5-files goes warm, migrations or schema changes always boot fresh. Wrong guesses fail safe toward fresh.