Terraform: Google Cloud Instance Startup Scripts & Provisioning with Compute Templates

[jwmarshall]

So I'm familiar with Terraform and have built environments on AWS with it. I have a new project on google cloud and I'm having an issue (or misunderstanding) on how to get my provisioning scripts/steps into an autoscaling group.

Terraform Version

Terraform v0.7.13

Affected Resource(s)

• google_compute_instance_template

Terraform Configuration Files

resource "google_compute_instance_template" "events_service_template" {
  name = "${var.environment}-events-service-template"
  machine_type = "${var.machine_type}"
  can_ip_forward = false

  tags = []

  disk {
    source_image = "ubuntu-os-cloud/ubuntu-1404-lts"
    disk_type = "pd-ssd"
    disk_size_gb = "30"
    auto_delete = true
    boot = true
  }

  network_interface {
    network = "default"
  }

  metadata {
    ssh-keys = "root:${file("${var.public_key_path}")}"
  }

  service_account {
    scopes = ["https://www.googleapis.com/auth/compute.readonly"]
  }

  provisioner "file" {
    source = "scripts/startup.sh"
    destination = "/root/startup.sh"

    connection {
      type = "ssh"
      user = "root"
      private_key = "${file("${var.private_key_path}")}"
      agent = false
    }
  }

  provisioner "remote-exec" {
    connection {
      type = "ssh"
      user = "root"
      private_key = "${file("${var.private_key_path}")}"
      agent = false
    }

    inline = [
      "chmod +x /root/startup.sh",
      "/root/startup.sh"
    ]
  }
}

Output

Error applying plan:

1 error(s) occurred:

* ssh: handshake failed: ssh: unable to authenticate, attempted methods [none publickey], no supported methods remain

Terraform does not automatically rollback in the face of errors.
Instead, your Terraform state file has been partially updated with
any resources that successfully completed. Please address the error
above and apply again to incrementally change your infrastructure.

References

I used a modified version of the google two-tier example.

[Dnefedkin]

google_compute_instance_template is a resource to define a template, not an VM. google_compute_instance is a resource to create a VM.
You're referring to google two-tier example, it uses google_compute_instance resource - https://github.com/hashicorp/terraform/blob/master/examples/google-two-tier/main.tf#L30

[lsm]

I think what people were trying to do is:

1. Define a VM template using google_compute_instance_template.
2. Use provisioners defined in google_compute_instance_template to provision a VM image as the image for instance group.
3. Use this template (and image) with google_compute_instance_group_manager to deploy VMs in an instance group. This will allow you to take advantage of the autoscaling feature.

This is simply not possible right now. But, it makes sense to have feature like this.

[hashibot[bot]]

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