Download LEGO binary
https://github.com/go-acme/lego/releases/

LEGO_VERSION=$(curl -s https://api.github.com/repos/go-acme/lego/releases/latest | grep '"tag_name"' | cut -d'"' -f4)
curl -L "https://github.com/go-acme/lego/releases/download/${LEGO_VERSION}/lego_${LEGO_VERSION}_linux_amd64.tar.gz" | tar -xz

Request certificate

DOMAIN=example.com
export OS_CLOUD=os-project1
export DESIGNATE_ZONE_NAME="${DOMAIN}."
export OS_REGION_NAME=de-de1

./lego run \
  --email foo@${DOMAIN} \
  --accept-tos \
  --dns designate \
  --domains "*.${DOMAIN}" \
  --domains ${DOMAIN}

List certificates

ls -l .lego/certificates

Convert to p12 file

openssl pkcs12 -passout "pass:" -export -in _.${DOMAIN}.crt -inkey _.${DOMAIN}.key -out _.${DOMAIN}.p12

Debug

export GODEBUG=http2debug=2 
export LEGO_LOG_LEVEL=debug 

# letsencrypt staging server
--server https://acme-staging-v02.api.letsencrypt.org/directory

Links
https://github.com/go-acme/lego/