Let's Encrypt for Duck DNS

Automatically generates Let's Encrypt certificates using a lightweight Docker container without requiring any ports to be exposed for DNS challenges.

Variables:

• DUCKDNS_TOKEN: Duck DNS account token (obtained from Duck DNS)
• DUCKDNS_DOMAIN: Full Duck DNS domain (e.g. test.duckdns.org)
• LETSENCRYPT_EMAIL: Email used for certificate renewal notifications (optional)
• LETSENCRYPT_WILDCARD: true or false, indicating whether the SSL certificate should be for subdomains only of DUCKDNS_DOMAIN (i.e. *.test.duckdns.org), or for the main domain only (i.e. test.duckdns.org) (default: false)
• TESTING: true or false, indicating whether a staging SSL certificate should be generated or not (default: false)

Note: The format of DUCKDNS_DOMAIN should be the same regardless of the value of LETSENCRYPT_WILDCARD.

Volumes:

• <certs>:/etc/letsencrypt: A named or hosted volume which allows SSL certificates to persist and be accessed by other containers

Note: If a hosted volume is used, the volume should be mounted in an unused directory in another container to prevent access conflicts.

TODO:

• Implement tests so depends_on can be used in docker-compose to prevent other containers from initialising until certificates are ready