Nginx proxy: unknown directive "ssl_early_data"

Troubleshooting
2

Just did some quick researching - it seems that the module you are attempting to utilize takes advantage of TLS 1.3, which must be enabled/included in your configuration file explicitly, or else the ssl_early_data module will fail.

Example (without any of the reverse proxy configuration):

root@95eed784a081:/etc/nginx/conf.d# cat 443.conf

server {
        listen 443 ssl default_server;
        listen [::]:443 ssl default_server;
        server_name _;

        ssl_protocols TLSv1.2 TLSv1.3;
        ssl_early_data on;
        #
        ssl_certificate /etc/ssl/certs/ssl-cert-snakeoil.pem;
        ssl_certificate_key /etc/ssl/private/ssl-cert-snakeoil.key;
[..]