[azurerm_kubernetes_cluster] working with autoscaler

[raphaelquati]

In our AKS (deployed using terraform), we've setup autoscaler (https://github.com/MicrosoftDocs/azure-docs/blob/master/articles/aks/autoscaler.md) manually (not using terraform - planned to use).

At creation time, we setup with only 1 agent.

resource "azurerm_kubernetes_cluster" "k8s" {
    name = "${var.cluster_name}"
    location = "${azurerm_resource_group.test.location}"
    resource_group_name = "${azurerm_resource_group.test.name}"
    dns_prefix = "${var.dns_prefix}"
    kubernetes_version = "1.11.4"

    agent_pool_profile {
        name            = "agentpool"
        count           = 1
        vm_size         = "Standard_F4s_v2"
        os_type         = "Linux"
        os_disk_size_gb = 30
        vnet_subnet_id  = "${azurerm_subnet.default.id}"
    }

After a while, autoscaler increase the number of agents. 
Terraform has only 1 agent at state. Any try to execute terraform apply, try to force AKS update.

[pawelpabich]

Would it make sense to rename this property from count to initial_count and change the behaviour so this value is only used once?

[tombuildsstuff]

hi @raphaelquati @pawelpabich

Thanks for opening this issue - apologies for the delayed response here!

If you're managing the count for the AKS Cluster externally it's possible to use the ignore_changes field within the lifecycle block to ignore changes to that value, as shown here:

resource "azurerm_kubernetes_cluster" "test" {
  lifecycle {
    ignore_changes = [ "agent_pool_profile.0.count" ]
  }
}

Whilst that will ignore changes to the count being different; if another field changes Terraform will still try and update the number of nodes in the cluster to match this. Would you be able to take a look and see if this approach works for you for the moment?

We could investigate obtaining the current cluster count and re-submitting that if the users explicitly ignored the value of the count field during an update - however this isn't something we support at this time.

Thanks!

[gree-gorey]

Didn't find any related issue so I'll ask here. Can you tell me if there are plans for including cluster autoscaler into azurerm_kubernetes_cluster resource? Maybe in 2.0? It would be great to reproduce this with Terraform:

$ az aks create \
  ...
  --enable-cluster-autoscaler \
  --min-count 1 \
  --max-count 3

Thanks

[MattMencel]

Autoscaling for AKS is in preview.

I don't think there's anything for it in azure-sdk-for-go yet.

It's enabled using this aks-preview extension. There's an SDK there.

Assuming this eventually goes GA, would it be possible for the aurerm_kubernetes_cluster resource to use min_count and max_count instead of count only if enable_cluster_autoscaler is set to true? And then ignore it as a change if it's above the min threshold?

resource "azurerm_kubernetes_cluster" "test" {
  name                = "acctestaks1"
  location            = "${azurerm_resource_group.test.location}"
  resource_group_name = "${azurerm_resource_group.test.name}"
  dns_prefix          = "acctestagent1"

  agent_pool_profile {
    name            = "default"
    enable_cluster_autoscaler = true
    min_count       = 1
    max_count       = 3
    vm_size         = "Standard_D1_v2"
    os_type         = "Linux"
    os_disk_size_gb = 30
  }

  service_principal {
    client_id     = "00000000-0000-0000-0000-000000000000"
    client_secret = "00000000000000000000000000000000"
  }

  tags {
    Environment = "Production"
  }
}

[bq1756]

I am requesting the same feature. It would be great to add "enable_cluster_autoscaler = true" into agent_pool_profile. Or, expand the "addon_profile" block to accept "cluster_autoscaler" settings.

[cwebbtw]

Would be great to see support for this

[landro]

AutoScaling has been supported in the go sdk since 2019-02-01: github.com/Azure/azure-sdk-for-go/services/containerservice/mgmt/2019-02-01/containerservice See models.go for details

[zloeber]

So who's going to hack it into provider? The preview feature for the aci connector is already available.

[DeanPH]

Any progress on this?

[jamesbibby]

Looks like there is a PR for it in the works #3361

[KIRY4]

Any updates? We really need this feature in terraform!

[invidian]

The PR is merged now, so it's available for testing. I guess with next release this issue can be closed.

[tombuildsstuff]

Fixed via #3361

[ghost]

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