lego

Lego is an independent, free, and open-source ACME (Automatic Certificate Management Environment) client and library written in Go. Its primary purpose is to automate the process of obtaining, renewing, and revoking SSL/TLS certificates from Let's Encrypt and other ACME-compatible Certificate Authorities (CAs), enabling HTTPS for everyone. Key capabilities include: - **ACME Protocol Support**: Fully implements ACME v2 (RFC 8555) with extensions such as ALPN Challenge (RFC 8737), IP address certificates (RFC 8738), Renewal Information (RFC 9773), and Profiles Extension. - **Extensive DNS Provider Integration**: Supports more than 200 DNS providers for automated DNS-01 challenge validation. This includes major cloud providers like AWS Route 53, Google Cloud, Azure DNS, Cloudflare, DigitalOcean, Linode, Vultr, and many others, as well as traditional registrars and niche providers. - **Multiple Challenge Types**: Robust implementation of HTTP-01, DNS-01, and TLS-ALPN-01 challenges. It also supports custom challenge solvers for specialized use cases. - **Certificate Management**: Users can register with a CA, obtain new certificates (including those based on existing CSRs), renew existing certificates, and revoke them when necessary. The tool supports SAN (Subject Alternative Name) certificates and CNAME records by default. - **Flexible Usage**: Lego can be used as a standalone Command Line Interface (CLI) for manual or scripted certificate management, or integrated as a Go library into other applications for automated certificate handling. - **Additional Features**: Includes certificate bundling, OCSP helper functions, and support for persistent DNS TXT record validation drafts. Lego is designed to be robust and flexible, making it suitable for both individual developers and large-scale infrastructure automation where secure HTTPS connections are required.