The following command can be used to create a docker container that uses a an existing SSL certificate. You can you use the following procure to convert a LetEncrypt cert into the format Duplicati needs.
Script for converting LetsEncrypt cert for use with Duplicati
docker run
–name=duplicati -h duplicati
-v /duplicati/data:/data
-v /usr/lib/duplicati/cert:/cert
-v :/share
Server/':/server
-p :8200
duplicati/duplicati
/usr/bin/duplicati-server --webservice-port=8200 --webservice-interface=any --webservice-sslcertificatefile=/cert/certificate.pfx
–webservice-sslcertificatepassword=