Automatically verify TXT record on GoogleDNS for wildcard SSL certificate generation

docker run \
    -e GCE_PROJECT=apple-pie-777 \
    -e GCE_DOMAIN="example.com" \
    -e [email protected] \
    -e DOMAINS=*.example.com \
    -v /volume2/dockerSecret/certbot/googledns-admin-key.json:/gcloud-service-account.json:ro \
    -v /volume2/dockerSecret/certbot:/certstore \
    -v /volume2/Certificates/SSL:/certstore/certificates \
    alexdo/letsencrypt-gcloud-dns