This OpenResty plugin automatically and transparently issues SSL certificates from Let’s Encrypt (a free certificate authority) as requests are received. It works like:
- A SSL request for a SNI hostname is received.
- If the system already has a SSL certificate for that domain, it is immediately returned (with OCSP stapling).
- If the system does not yet have an SSL certificate for this domain, it issues a new SSL certificate from Let’s Encrypt. Domain validation is handled for you. After receiving the new certificate (usually within a few seconds), the new certificate is saved, cached, and returned to the client (without dropping the original request).
This uses the
ssl_certificate_by_lua functionality in OpenResty 18.104.22.168+.