Automating Let’s Encrypt certificate renewal

Ninety-day certificates make renewal automation necessary. The important control is proving that a renewed certificate reaches every serving process before the existing certificate expires.

Choose and protect validation

Use an ACME challenge compatible with the hosting topology. Ensure redirects, proxies and multiple front ends serve the challenge consistently, and constrain DNS credentials if DNS validation is required.

Deploy after renewal

Reload or restart each TLS terminator safely after obtaining the certificate, including secondary nodes and containers. Validate the served serial and chain externally rather than trusting the file timestamp on one host.

Monitor the outcome

Alert on days remaining at the public endpoint and on repeated renewal failures. Run dry-run renewal after configuration changes and retain enough logs to distinguish rate limiting, challenge routing and account failures.