DirectAdmin: How to force Let's Encrypt to use DST Root CA X3

This is a solution for servers with DirectAdmin and custombuild only.

Here is a patch for Let's Encrypt script from DirectAdmin to force it to use "DST Root CA X3" instead of "ISRG Root X1" when issuing SSL certificates:

• https://github.com/poralix/directadmin-utils/blob/master/letsencrypt/poralix_patch_chain.sh
  

For installation run as root:

mkdir -p /usr/local/directadmin/custombuild/custom/hooks/letsencrypt/post/
cd /usr/local/directadmin/custombuild/custom/hooks/letsencrypt/post/
wget -O poralix_patch_chain.sh https://raw.githubusercontent.com/poralix/directadmin-utils/master/letsencrypt/poralix_patch_chain.sh
chmod 750 poralix_patch_chain.sh
/usr/local/directadmin/custombuild/build letsencrypt

The patch will be applied automatically every time by running command:

/usr/local/directadmin/custombuild/build letsencrypt

or you might execute the sctipt manually as needed:

/usr/local/directadmin/custombuild/custom/hooks/letsencrypt/post/poralix_patch_chain.sh

or with cron.

That's it.