NGINX config for using Let's Encrypt via the acme.sh client, assumes the existence of a `/var/www/.letsencrypt` directory and enforces HTTPS while allowing cert issue/renewal over HTTP

domain.com

server {
        listen 80;
        server_name domain.com;
        
        include letsencrypt_params;
}

server {
        listen 443;
        server_name domain.com;

        include ssl_params;
        ssl_certificate /root/.acme.sh/domain.com/domain.com.cer;
        ssl_certificate_key /root/.acme.sh/domain.com/domain.com.key;
        ssl_trusted_certificate /root/.acme.sh/domain.com/fullchain.cer;
        
        location / {
                //
        }
}

letsencrypt_params

# USAGE TEMPLATE (within server block):
# ------------------------------------------------------------------------------
#   listen 80;
#   server_name domain.com;
#   include letsencrypt_params;
# ------------------------------------------------------------------------------
# Command to issue letsencrypt SSL certificates using acme.sh:
#    acme.sh --issue -d domain.com -w /var/www/.letsencrypt

root /var/www/.letsencrypt/;
index index.html;

location / {
        rewrite ^/(.*)$ https://$host$request_uri permanent;
}

location ^~ /.well-known/ {
        try_files $uri $uri/ =404;
}

ssl_params

# USAGE TEMPLATE (within server block):
# ------------------------------------------------------------------------------
#   include ssl_params;
#   ssl_certificate /root/.acme.sh/domain.com/fullchain.cer;
#   ssl_certificate_key /root/.acme.sh/domain.com/domain.com.key;
#   ssl_trusted_certificate /root/.acme.sh/domain.com/fullchain.cer;
# ------------------------------------------------------------------------------
# Generate required dhparam.pem file with:
#   openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048
#
# SOURCE: https://gist.github.com/plentz/6737338

ssl on;
# enable session resumption to improve https performance
# http://vincent.bernat.im/en/blog/2011-ssl-session-reuse-rfc5077.html
ssl_session_cache shared:SSL:50m;
ssl_session_timeout 5m;

# Diffie-Hellman parameter for DHE ciphersuites, recommended 2048 bits
ssl_dhparam /etc/nginx/ssl/dhparam.pem;

# enables server-side protection from BEAST attacks
# http://blog.ivanristic.com/2013/09/is-beast-still-a-threat.html
ssl_prefer_server_ciphers on;
# disable SSLv3(enabled by default since nginx 0.8.19) since it's less secure then TLS http://en.wikipedia.org/wiki/Secure_Sockets_Layer#SSL_3.0
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
# ciphers chosen for forward secrecy and compatibility
# http://blog.ivanristic.com/2013/08/configuring-apache-nginx-and-openssl-for-forward-secrecy.html
ssl_ciphers "ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES256-GCM-SHA384:AES128-GCM-SHA256:AES256-SHA256:AES128-SHA256:AES256-SHA:AES128-SHA:DES-CBC3-SHA:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!MD5:!PSK:!RC4";

# enable ocsp stapling (mechanism by which a site can convey certificate revocation information to visitors in a privacy-preserving, scalable manner)
# http://blog.mozilla.org/security/2013/07/29/ocsp-stapling-in-firefox/
resolver 8.8.8.8;
ssl_stapling on;

To anyone reading this, this is outdated and I'm not sure it was ever right for nginx because of the missing chain cert.

In domain.com file, change:

    ssl_certificate /root/.acme.sh/domain.com/domain.com.cer;
    ssl_certificate_key /root/.acme.sh/domain.com/domain.com.key;
    ssl_trusted_certificate /root/.acme.sh/domain.com/fullchain.cer;

to:

    ssl_certificate /root/.acme.sh/domain.com/fullchain.cer;
    ssl_certificate_key /root/.acme.sh/domain.com/domain.com.key;

Then in server config, make sure to change the listen directive to:

listen 443 ssl http2;
listen [::]:443 ssl http2;

And use latest Mozilla SSL generator ssl_config options. Currently:

ssl_session_timeout 1d;
ssl_session_cache shared:MozSSL:10m;  # about 40000 sessions
ssl_session_tickets off;

# Diffie-Hellman parameter for DHE ciphersuites, recommended 2048 bits
ssl_dhparam /etc/nginx/ssl/dhparam.pem;

# enables server-side protection from BEAST attacks
# http://blog.ivanristic.com/2013/09/is-beast-still-a-threat.html
# disable SSLv3(enabled by default since nginx 0.8.19) since it's less secure then TLS http://en.wikipedia.org/wiki/Secure_Sockets_Layer#SSL_3.0
# intermediate configuration
ssl_protocols TLSv1.2 TLSv1.3;
ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384;
ssl_prefer_server_ciphers off;

# HSTS (ngx_http_headers_module is required) (63072000 seconds)
add_header Strict-Transport-Security "max-age=63072000" always;

# OCSP stapling
ssl_stapling on;
ssl_stapling_verify on;

# enable ocsp stapling (mechanism by which a site can convey certificate revocation information to visitors in a privacy-preserving, scalable manner)
# http://blog.mozilla.org/security/2013/07/29/ocsp-stapling-in-firefox/
resolver 1.1.1.1 1.0.0.1 [2606:4700:4700::1111] [2606:4700:4700::1001];

Giving me an A+ at Qualy's.