terraform heroku自动证书管理

Question

我找不到有关Heroku自动证书管理的任何文档。 heroku_cert的{​​{3}}仅指手动生成的证书：

# Create a new Heroku app
resource "heroku_app" "default" {
  name = "test-app"
}

# Add-on SSL to application
resource "heroku_addon" "ssl" {
  app  = "${heroku_app.default.name}"
  plan = "ssl"
}

# Establish certificate for a given application
resource "heroku_cert" "ssl_certificate" {
  app               = "${heroku_app.default.name}"
  certificate_chain = "${file("server.crt")}"
  private_key       = "${file("server.key")}"
  depends_on        = "heroku_addon.ssl"
}

certificate_chain和private_key是必需的，我不知道该从哪里获得。