openssl genrsa -out server.key 2048

openssl req -new -key server.key -out server.csr

openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt

$ python3 -m http.server 8000

    server {
        listen       443 ssl;
        server_name  localhost;
        
        ssl_certificate      /etc/nginx/server.crt;
        ssl_certificate_key  /etc/nginx/server.key;
        
        ssl_session_timeout  5m;
        
        ssl_protocols  TLSv1 TLSv1.1 TLSv1.2;
        ssl_prefer_server_ciphers   on;
        
        location / {
            proxy_pass              http://localhost:8000;
            proxy_http_version      1.1;
            proxy_set_header        Connection "";
            proxy_set_header        Host            $host;
            proxy_set_header        X-Real-IP       $remote_addr;
            proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header        X-Forwarded-Proto https;
        }
    }

user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;

events {
    worker_connections 768;
}

http {
    sendfile on;
    tcp_nopush on;
    types_hash_max_size 2048;

    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3;
    ssl_prefer_server_ciphers on;

    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;

    gzip on;

    server {
        listen 80;
        server_name localhost;
        location / {
            proxy_pass http://localhost:8000;
        }
    }

    server {
        listen       443 ssl;
        server_name  localhost;
        
        ssl_certificate      /etc/nginx/server.crt;
        ssl_certificate_key  /etc/nginx/server.key;
        
        ssl_session_timeout  5m;
        
        ssl_protocols  TLSv1 TLSv1.1 TLSv1.2;
        ssl_prefer_server_ciphers   on;
        
        location / {
            proxy_pass              http://localhost:8000;
            proxy_http_version      1.1;
            proxy_set_header        Connection "";
            proxy_set_header        Host            $host;
            proxy_set_header        X-Real-IP       $remote_addr;
            proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header        X-Forwarded-Proto https;
        }
    }

    include /etc/nginx/conf.d/*.conf;
    include /etc/nginx/sites-enabled/*;
}

$ sudo service nginx restart