main.tf

provider "acme" {
  server_url = "https://acme-staging-v02.api.letsencrypt.org/directory"
}

resource "tls_private_key" "private_key" {
  algorithm = "RSA"
}

resource "acme_registration" "reg" {
  account_key_pem = "${tls_private_key.private_key.private_key_pem}"
  email_address   = "me@gmail.com"
}

resource "acme_certificate" "certificate" {
  account_key_pem           = "${acme_registration.reg.account_key_pem}"
  common_name               = "my.host.nm"

  dns_challenge {
    provider = "gcloud"
    config {
      GCE_PROJECT = "my-project"
    }
  }
}