Add support for using a rolling upgrade policy on a scale set that has MaxSurge enabled

[jmlaubach]

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Description

Currently, when you create a Linux VMSS resource with the upgrade mode set to Rolling, and a rolling_upgrade_policy is set, you can only utilize the default behavior where VMs are brought down in patches to be updated. You are unable to use MaxSurge to change the behavior to where the rolling upgrade creates new VMs first before bringing old VMs down.

It would be helpful as the user to be able to enable the MaxSurge feature for Rolling Upgrade Policies on a scale set. This would allow for resource intensive applications running to not lose any resources by VMs in the scale set being brought down first rather than new VMs being created with updated settings.

New or Affected Resource(s)/Data Source(s)

azurerm_linux_virtual_machine_scale_set

Potential Terraform Configuration

resource "azurerm_linux_virtual_machine_scale_set" "example" {
  name                = "example-vmss"
  resource_group_name = azurerm_resource_group.example.name
  location            = azurerm_resource_group.example.location
  sku                 = "Standard_F2"
  instances           = 1
  admin_username      = "adminuser"
  upgrade_mode        = "Rolling"

  rolling_upgrade_policy = {
    max_batch_instance_percent = 20
    max_unhealthy_instance_percent = 10
    max_unhealthy_upgraded_instance_percent = 10
    pause_time_between_batches = "PT10M"
    maxsurge = true
  }

References

No response

[harshavmb]

Hi @jmlaubach ,

Thanks for opening this issue. At this point in time MaxSurge is still in preview mode. I have made changes & opened PR here but it is in draft mode.

I ask for Hashicorp review when the stable version is released.

[jmlaubach]

@harshavmb

Thanks for the update! Was wondering if this wasn't an option due to it still being in preview mode in Azure. Thank you!

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