dhparam.pem necessary for nginix web server

This morning I was alerted by Wachete that the derivationmap.net website was unavailable. 

I logged into the digitalocean.com virtual private server (VPS) and used top to see that the container processes were running.

Normally the command I run to start the Docker containers is

docker-compose up --build --force-recreate --remove-orphans --detach

To troubleshoot, I ran

docker-compose up --build --force-recreate --remove-orphans

and the output was

Successfully built 0ffaac97e769
Successfully tagged v7_pickle_web_interface_nginx:latest
Recreating v7_pickle_web_interface_flask_1 ... done
Recreating v7_pickle_web_interface_nginx_1 ... done
Attaching to v7_pickle_web_interface_flask_1, v7_pickle_web_interface_nginx_1
nginx_1  | 2021/07/10 11:48:41 [emerg] 1#1: PEM_read_bio_DHparams("/certs/dhparam.pem") failed (SSL: error:0909006C:PEM routines:get_name:no start line:Expecting: DH PARAMETERS)
nginx_1  | nginx: [emerg] PEM_read_bio_DHparams("/certs/dhparam.pem") failed (SSL: error:0909006C:PEM routines:get_name:no start line:Expecting: DH PARAMETERS)
v7_pickle_web_interface_nginx_1 exited with code 1

The fix was to point nginix to the dhparam.pem file.

https://security.stackexchange.com/questions/94390/whats-the-purpose-of-dh-parameters