Hi duffyevan,
you can override the protocol in config.php with
'overwriteprotocol' => 'https',
see Config.php Parameters :: ownCloud Documentation
This tells ownCloud to create links with https protocol instead of http
Edit: You can set this value with occ as well, so for docker this would be
docker exec --user www-data <owncloud-container-name> php occ config:system:set overwriteprotocol --value=https