Letsencrypt hook to generate combined fullchain+privkey certificates for software like Haproxy

generate-bundle-certs.sh

#!/bin/bash

# SAVE TO /etc/letsencrypt/renewal-hooks/post/generate-bundle-certs.sh
# chmod a+x /etc/letsencrypt/renewal-hooks/post/generate-bundle-certs.sh

find /etc/letsencrypt/live -mindepth 1 -maxdepth 1 -type d -print0 | while IFS='' read -d $'\0' dir; do
    # Update only if necessary
    test -e "$dir/fullchain.pem" -a \
         -e "$dir/privkey.pem" -a \
         -e "$dir/fullchain_and_privkey.pem" && \
         cmp <(cat "$dir/fullchain.pem" "$dir/privkey.pem") <(cat "$dir/fullchain_and_privkey.pem")
    if [ $? -eq 0 ]; then
        echo "already updated: $dir/fullchain_and_privkey.pem"
        continue
    else
        echo "updating: $dir/fullchain_and_privkey.pem"
        # Atomic update
        cat "$dir/fullchain.pem" "$dir/privkey.pem" > "$dir/fullchain_and_privkey.pem.new"
        mv -f "$dir/fullchain_and_privkey.pem.new" "$dir/fullchain_and_privkey.pem"
    fi
done

For blog post: https://selivan.github.io/2020/12/02/letsencrypt-auto-generate-bundle-certificates-for-haproxy.html