provisioning - 如何使用Terraform Cloud作为远程后端发送本地文件？

我正在创建AWS EC2实例，并且正在使用Terraform Cloud作为后端。

在./main.tf中：

terraform {

    required_version = "~> 0.12"
    backend "remote" {
    hostname     = "app.terraform.io"
    organization = "organization"
    workspaces { prefix = "test-dev-" }

  }

在./modules/instances/function.tf中

resource "aws_instance" "test" {
    ami = "${var.ami_id}"
    instance_type = "${var.instance_type}"
    subnet_id = "${var.private_subnet_id}"
    vpc_security_group_ids = ["${aws_security_group.test_sg.id}"]
    key_name      = "${var.test_key}"                                        

    tags = {
        Name = "name"
        Function = "function"
    }

  provisioner "remote-exec" {
    inline = [
      "sudo useradd someuser"
    ]

    connection {
      host = "${self.public_ip}"
      type        = "ssh"
      user        = "ubuntu"
      private_key = "${file("~/.ssh/mykey.pem")}"
    }
  }
}

结果，我得到了以下错误：

Call to function "file" failed: no file exists at /home/terraform/.ssh/...

因此，这里发生的是terraform想在Terraform Cloud中而不是我的本地计算机中查找文件。如何从本地计算机传输文件并仍然使用Terraform Cloud？