Dependency issue between instance_template and instance_group_manager?

[synhershko]

It seems to be impossible to update an instance template without hitting the following error on apply:

google_compute_instance_template.elasticsearch2-master: Error deleting instance template: googleapi: Error 400: The instance_template resource 'projects/myproject-119711/global/instanceTemplates/terraform-20180606093020757400000002' is already being used by 'projects/myproject-119711/zones/europe-west1-b/instanceGroupManagers/elasticsearch2-master', resourceInUseByAnotherResource

Whether or not I set the instance_template name myself, every attempt to make a change fails with this error, likely because of a dependency issue with the instance_group_manager, or a bug relating to finding and updating that resource?

Using latest terraform and gcp provider

[rosbo]

Hi,

You can use the create_before_destroy feature for this.

Update your instance template config as follow:

resource "google_compute_instance_template" "test-it" {
  # Don't use the name field since the newly created template can't have the same name
  name_prefix = "test-it"
  ...
  lifecycle {
    create_before_destroy = true
  }
}

With this config, the proper order will be respected:

google_compute_instance_template.test-it: Still creating... (10s elapsed)
google_compute_instance_template.test-it: Creation complete after 12s (ID: test-it20180606175118068900000001)
google_compute_instance_group_manager.test-igm: Modifying... (ID: test-igm)
  instance_template: "https://www.googleapis.com/compute/v1/projects/[redacted]/global/instanceTemplates/test-it" => "https://www.googleapis.com/compute/beta/projects/[redacted]/global/instanceTemplates/test-it20180606175118068900000001"
google_compute_instance_group_manager.test-igm: Still modifying... (ID: test-igm, 10s elapsed)
google_compute_instance_group_manager.test-igm: Still modifying... (ID: test-igm, 20s elapsed)
google_compute_instance_group_manager.test-igm: Modifications complete after 22s (ID: test-igm)
google_compute_instance_template.test-it.deposed: Destroying... (ID: test-it)
google_compute_instance_template.test-it (deposed #0): Still destroying... (ID: test-it, 10s elapsed)
google_compute_instance_template.test-it.deposed: Destruction complete after 11s

Apply complete! Resources: 1 added, 1 changed, 1 destroyed.

Let me know if that solves your problem

[rosbo]

I closed the issue because I am fairly certain this should solve your issue. However, if it doesn't, please reopen the issue.

Thank you

[synhershko]

It did, thanks!

[ghost]

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