Resize boot disk cause destroy and recreate VM

[shumak80]

Terraform Version

Terraform v1.2.2

Affected Resource(s)

• google_compute_instance

Terraform Configuration Files

resource "google_compute_instance" "default" {
name = "vm1"
machine_type = "e2-standard-2"
zone = "europe-west3-a"

boot_disk {
initialize_params {
image = "debian-cloud/debian-10"
size = "20"
type = "pd-standard"
}
}
network_interface {
subnetwork = "default"
}
}

Expected Behavior

GCP provider support resize of disk without destroy/recreate the instance.

Actual Behavior

The VM is deleted and recreated.
GCP is able to resize the disk on the fly even boot disk so I expect to have the size increased but without deleting re-creating the VM.

Steps to Reproduce

1. terraform apply
2. change size of the disk to 25
3. terraform apply

Important Factoids

References

This issue was already solved in #861 , but it was for resource google_compute_disk.

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[edwardmedia]

@shumak80 did you notice the discussion in #8597 Is that relevant?

[shumak80]

@edwardmedia It's not related to #8597 ... #8597 is about downsize disk. My case is about increase size of disk. It can be done without any changes to VM instance.

[edwardmedia]

@shumak80 That is the boot_disk, right? Where did you see you can resize the boot_disk without recreation?

[shumak80]

@edwardmedia It's a common thing ... you can read about this here. Even you can try it via console. If you create a boot disk as separate resource and use it as source for boot disk, then you are able to resize boot disk without re-creation.

[shuyama1]

It seems that in-place update for this field is not yet supported when the feature was implemented. Making it updatable is a feature request and marking this issue as enhancement then.

[shumak80]

Ok. Then it should be mentioned in terraform documentation. To warn everybody that this feature is not ready yet.

[rileykarson]

See #6087 for prior discussion on the matter, mostly #6087 (comment). initialize_params indicates "I want the instance to have been created with these properties" meaning that recreating it when changed is the expected behaviour of the provider.

[github-actions]

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