Everything the WhatsApp service needs runs on one small DigitalOcean Droplet in London: the app, Redis, PostgreSQL, Prometheus, Grafana, a Redis exporter and Caddy, seven services in one Compose file. The Droplet, its firewall and its DNS are described in Terraform, so the next person reads a file instead of clicking through a panel. Only Caddy faces the network, on ports 22, 80 and 443; the databases and the metrics publish no ports at all. Certificates renew themselves. Production is reached through one deploy script with 25 modes (deploy, dry run, status, restart, template snapshot, sender health, retention, erasure and so on), never by hand, and a git tag named production always points at the commit that is live. Backups of the session store go to a private bucket every night and expire on a lifecycle rule. It costs six dollars a month.