typhoon/azure/container-linux/kubernetes/workers/workers.tf

locals {
  # Channel for a Container Linux derivative
  # coreos-stable -> Container Linux Stable
  channel = element(split("-", var.os_image), 1)
}

# Workers scale set
resource "azurerm_virtual_machine_scale_set" "workers" {
  resource_group_name = var.resource_group_name

  name                   = "${var.name}-workers"
  location               = var.region
  single_placement_group = false

  sku {
    name     = var.vm_type
    tier     = "standard"
    capacity = var.worker_count
  }

  # boot
  storage_profile_image_reference {
    publisher = "CoreOS"
    offer     = "CoreOS"
    sku       = local.channel
    version   = "latest"
  }

  # storage
  storage_profile_os_disk {
    create_option     = "FromImage"
    caching           = "ReadWrite"
    os_type           = "linux"
    managed_disk_type = "Standard_LRS"
  }

  os_profile {
    computer_name_prefix = "${var.name}-worker-"
    admin_username       = "core"
    custom_data          = data.ct_config.worker-ignition.rendered
  }

  # Azure mandates setting an ssh_key, even though Ignition custom_data handles it too
  os_profile_linux_config {
    disable_password_authentication = true

    ssh_keys {
      path     = "/home/core/.ssh/authorized_keys"
      key_data = var.ssh_authorized_key
    }
  }

  # network
  network_profile {
    name                      = "nic0"
    primary                   = true
    network_security_group_id = var.security_group_id

    ip_configuration {
      name      = "ip0"
      primary   = true
      subnet_id = var.subnet_id

      # backend address pool to which the NIC should be added
      load_balancer_backend_address_pool_ids = [var.backend_address_pool_id]
    }
  }

  # lifecycle
  upgrade_policy_mode = "Manual"
  # eviction policy may only be set when priority is Low
  priority            = var.priority
  eviction_policy     = var.priority == "Low" ? "Delete" : null
}

# Scale up or down to maintain desired number, tolerating deallocations.
resource "azurerm_monitor_autoscale_setting" "workers" {
  resource_group_name = var.resource_group_name

  name     = "${var.name}-maintain-desired"
  location = var.region

  # autoscale
  enabled            = true
  target_resource_id = azurerm_virtual_machine_scale_set.workers.id

  profile {
    name = "default"

    capacity {
      minimum = var.worker_count
      default = var.worker_count
      maximum = var.worker_count
    }
  }
}

# Worker Ignition configs
data "ct_config" "worker-ignition" {
  content      = data.template_file.worker-config.rendered
  pretty_print = false
  snippets     = var.clc_snippets
}

# Worker Container Linux configs
data "template_file" "worker-config" {
  template = file("${path.module}/cl/worker.yaml.tmpl")

  vars = {
    kubeconfig             = indent(10, var.kubeconfig)
    ssh_authorized_key     = var.ssh_authorized_key
    cluster_dns_service_ip = cidrhost(var.service_cidr, 10)
    cluster_domain_suffix  = var.cluster_domain_suffix
  }
}