roles/nginx: add tls 1.2 support

roles/nginx/defaults/main.yml

@@ -4,4 +4,5 @@ monitoring_vhosts: []
 nginx_site_fqdn: '{{ ansible_hostname }}.{{ domain }}'
 nginx_site_alternate_fqdns: []
 nginx_proxy_protocol: true
+nginx_tls_1_2: false
 ...

roles/nginx/templates/base.j2

@@ -27,7 +27,10 @@ server {
     ssl_session_cache shared:MozSSL:10m;
     ssl_session_tickets off;
     # modern configuration
-    ssl_protocols TLSv1.3;
+    ssl_protocols TLSv1.3 {{ 'TLSv1.2' if nginx_tls_1_2 }};
+    {% if nginx_tls_1_2 %}
+    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;
+    {% endif %}
     ssl_prefer_server_ciphers off;
     # HSTS (2 years, no preloading)
     add_header Strict-Transport-Security "max-age=63072000" always;