Letsencrypt Let's encrypt will work on subdomain using a Cname record?

That's a tricky one as cdn.mydomain.com needs to be

1. pointing to same site as your mydomain.com so same IP (that you configure in cdn settings as your origin IP)
2. if using cloudflare strict ssl and not flexible ssl, needs for origin to have SSL certificate and HTTPS as well unless using flexible ssl which can be non-HTTPS nginx origin

are you using flexible ssl or full ssl for cloudflare ?

you can use a cloudflare page fule for cdn.mydoman.com requests so that it uses flexible ssl and just have a non-https cdn.mydomain.com nginx vhost via centmin.sh menu option 2 which uses your mydomain.com's web root in nginx vhost config so access to non-http cdn.mydomain.com will point to same web root as mydomain.com

 

you can just use cdn.mydomain.com via centmin.sh menu option 2 with letsencrypt ssl issuance and change the web root to point to mydomain.com's version i.e. method 2 below.

You currently can't automate parking one HTTPS SSL cert enabled domain (yourparkeddomain.com) on top of another HTTPS SSL cert enabled domain (domain.com) as you need for each domain to have it's own SSL certificate reference and Centmin Mod 123.09beta01 can only do one domain Letsencrypt SSL certificate issuance per centmin.sh menu option 2, 22 or nv command runs. See below instructions for Parked HTTPS SSL Domains.

Parked HTTPS SSL Domains

Parked domains meaning different domains and/or subdomains all point to same IP address and site content when accessed in a web browser. These methods outlined below are NOT for multiple domains pointing to different site/content.

As there's no way to automate such you have 2 manual methods available

Manual Method 1 - Do manual Nginx vhost creation via the underlying acme.sh client. If you have not yet created any of the intended domains/nginx vhosts, you can use addons/acmetool.sh directly via SANS Multi-Domain SSL Certificates method. Otherwise, if some or all intended domains/nginx vhosts have already been created then use manual method as discussed in steps in this post here and here.

Manual Method 2 - create a domain Nginx HTTPS vhost site for each domain.

It would be a manual process which involves creating the parked domain's own Nginx HTTPS SSL cert enabled vhost via centmin.sh menu option 2 or nv command and setting it up with valid working DNS A records for domain's www and non-www versions if main domain or DNS A for subdomain and ensure it's working and select letsencrypt option with live default HTTPS SSL cert and then editing it's nginx config file at /usr/local/nginx/conf/conf.d/yourparkeddomain.com.ssl.conf and then just changing root path to your origin domain's root

in /usr/local/nginx/conf/conf.d/yourparkeddomain.com.ssl.conf change it's default public web root path from

Code (Text):

root /home/nginx/domains/yourparkeddomain.com/public

to

Code (Text):

root /home/nginx/domains/domain.com/public

which now matches the public web root for domain.com nginx vhost listed in domain.com nginx vhost config file at /usr/local/nginx/conf/conf.d/domain.com.ssl.conf

now both yourparkeddomain.com and domain.com public web root paths point to /home/nginx/domains/domain.com/public so access via the domains will serve files located in /home/nginx/domains/domain.com/public. It does mean that any configurations you manually setup in /usr/local/nginx/conf/conf.d/domain.com.ssl.conf need to be replicated in /usr/local/nginx/conf/conf.d/yourparkeddomain.com.ssl.conf.

you can use common include file templates you set to make it easier i.e. if in both /usr/local/nginx/conf/conf.d/yourparkeddomain.com.ssl.conf and /usr/local/nginx/conf/conf.d/domain.com.ssl.conf you have a custom location content like

Code (Text):

location /test {
  include /usr/local/nginx/conf/php.conf;
  try_files $uri $uri/ /index.php
}

you could place that location /test context into a custom template file you create at /home/nginx/domains/domain.com/common_includes.conf and reference it in both /usr/local/nginx/conf/conf.d/yourparkeddomain.com.ssl.conf and /usr/local/nginx/conf/conf.d/domain.com.ssl.conf as

Code (Text):

include /home/nginx/domains/domain.com/common_includes.conf;

Final note in origin domain's nginx vhost at /usr/local/nginx/conf/conf.d/domain.com.ssl.conf also add canonical header to ensure search engines visiting domain.com know content is originally at domain.com to prevent search engines from flagging yourparkeddomain.com content as duplicated content.

Code (Text):

add_header Link "<http://domain.com$request_uri>; rel=\"canonical\"";

i.e. placing the header just below existing add_header entries in default nginx vhost config for HTTPS SSL domains

Code (Text):

  # before enabling HSTS line below read centminmod.com/nginx_domain_dns_setup.html#hsts
  #add_header Strict-Transport-Security "max-age=31536000; includeSubdomains;";
  #add_header X-Frame-Options SAMEORIGIN;
  add_header X-Xss-Protection "1; mode=block" always;
  add_header X-Content-Type-Options "nosniff" always;
  #add_header Referrer-Policy "strict-origin-when-cross-origin";
  add_header Link "<http://domain.com$request_uri>; rel=\"canonical\"";

then restart nginx and php-fpm services

Code (Text):

nprestart

To confirm just run curl command in SSH against your domain i.e. curl headers and grep filter for word canonical

Code (Text):

curl -sI https://domain.com | grep canonical

output would be something like

Code (Text):

curl -sI https://domain.com | grep canonical
Link: <http://domain.com/>; rel="canonical"

 

Try enabling CNAME Flattening in Cloudflare DNS tab

i.e.

 

Need to have paid CF pro, business or enterprise plan for non root flattening Understand and configure CNAME Flattening

so should work for you if CNAME IP is same as your domain root main IP.

other option is in your main domain nginx vhost add to server_name, the cdn.domain.com as a alias/park and add page rule for changing to CF Full (non-strict) and see it would try to contact cdn.domain.com and centmin mod nginx will catch it in that main domain nginx vhost and still pass through as CF Full (non-strict) doesn't validate the SSL certification/HTTPS on origin main domain HTTPS backend which would give invalid SSL cert error as cdn.domain.com isn't in main domain's SSL certificate common name list/san list.

 

that's probably why letsencrypt is failing then - you'd need to turn of cloudflare proxying (use grey cloud and not orange cloud) so cloudflare is used only for DNS

 

CDN already accelerates your static files ? or am I missing something else ? your don't need a 3rd party CDN if you use Cloudflare - so it's either use CDN or Cloudflare not both unless your CDN supports Cloudflare specifically.

 

then method 1's manual steps might be the way to add cdn.mydomain.com to your mydomain.com letsencrypt ssl cert

 

sounds like from Letsencrypt - Official acmetool.sh testing thread for Centmin Mod 123.09beta01 you need to use acmetool.sh DNS validation for letsencrypt via Cloudflare API

• Cloudflare API Support in DNS Mode

 

what's output for

Code (Text):

grep -in 'ssl_' /usr/local/nginx/conf/conf.d/cdn.mydomain.com.ssl.conf 

and

Code (Text):

ls -lahrt /usr/local/nginx/conf/ssl/cdn.mydomain.com/