Create VM

openstack server create foo-certbot \
    --image "Ubuntu 18.04" \
    --flavor m1.small \
    --key-name foo-key \
    --network foo-net \
    --security-group foo-sec

Add floating IP

FLOATING_IP=$(openstack floating ip create public -c floating_ip_address -f value)
echo ${FLOATING_IP}
openstack server add floating ip foo-certbot ${FLOATING_IP}

Install certbot

ssh ubuntu@${FLOATING_IP} sudo apt update && sudo apt install -y certbot

Create wildcard certificates

export DOMAINS="
dev.example.com
www.example.com
"

for DOMAIN in ${DOMAINS}; do
    sudo certbot certonly \
    --manual \
    --manual-public-ip-logging-ok \
    --register-unsafely-without-email \
    --agree-tos \
    --preferred-challenges dns-01 \
    --server https://acme-v02.api.letsencrypt.org/directory \
    -d \*.${DOMAIN}
done

Debug

watch dig TXT _acme-challenge.dev.example.com

for DOMAIN in ${DOMAINS}; do
    dig TXT _acme-challenge.${DOMAIN}
done | egrep '^_acme-challenge'