Automating TLS Certificate Lifecycle with Let's Encrypt and ACME

Your production site just went down at 3 AM because someone forgot to renew a certificate. Again. The manual renewal process that worked fine for two servers has become a liability now that you're managing fifty. Every quarter, the same ritual: calendar reminders, SSH sessions, certbot commands, nginx reloads, and the lingering anxiety that you missed one. Until you did. Certificate expiration is the silent killer of uptime. It doesn't trigger your APM alerts. Load balancers report the backend as healthy right up until browsers start throwing ERR_CERT_DATE_INVALID. By the time your on-call engineer figures out what's happening, customers have already screenshot the security warning and posted it to Twitter. The fundamental issue isn't negligence—it's that manual processes decay. The engineer who set up the original certificates left the company. The renewal documentation lives in a Confluence page that hasn't been updated since 2019. The cron job that was supposed to handle this silent