upgrade_mode change for azurerm_virtual_machine_scale_set forces recreation

[sean-t-shen]

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Terraform (and AzureRM Provider) Version

erraform v0.13.6

• provider registry.terraform.io/hashicorp/azurerm v2.44.0

Your version of Terraform is out of date! The latest version
is 0.15.1. You can update by downloading from https://www.terraform.io/downloads.html

azurerm_virtual_machine_scale_set

Terraform Configuration Files

# Copy-paste your Terraform configurations here - for large Terraform configs,
# please use a service like Dropbox and share a link to the ZIP file. For
# security, you can also encrypt the files using our GPG public key: https://keybase.io/hashicorp

Debug Output

Panic Output

Expected Behaviour

It can be in place update. Azure itself does not require the recreation of the vmss for the change of this parameter, nor does it require even a reboot. Why should Terraform require recreation?

Steps to Reproduce

with a vmss upgrade mode set as manual, change the parameter to auto, and terraform will ask to recreate the vmss
with a vmss upgrade mode set as auto, change the parameter to manual, and terraform will ask to recreate the vmss

Important Factoids

References

• #0000

[sean-t-shen]

One more related issue:

Actually, upgrade_mode is the recognized key, instead of

automatic_os_upgrade
upgrade_policy_mode

Is the documentation lagging behind?

Thanks
Sean

[Thilas]

I have the same issue using terraform 1.5.7 with azurerm 3.103.1 while switching from Automatic to Rolling. But Azure Portal allows to switch upgrade mode without any trouble. Any idea why it wants to recreate with terraform?