module "azure_node_pool" {
  source = "../../modules/azure-node-pool"

  # Cluster configuration
  tenant_cluster_name = "charlie"
  pool_name          = "default"

  # Pool sizing
  pool_size     = 3
  pool_min_size = 1
  pool_max_size = 9

  # Azure configuration
  azure_location            = "italynorth"
  azure_resource_group_name = "kamaji"
  azure_vnet_name          = "kamaji-vnet"
  azure_subnet_name        = "kamaji-subnet"

  # VM configuration
  vm_size            = "Standard_D2s_v3"
  assign_public_ip   = true
  node_disk_size     = 30
  node_disk_type     = "Premium_LRS"

  # Autoscaling
  enable_autoscaling        = true
  scale_out_cpu_threshold   = 75
  scale_in_cpu_threshold    = 25

  # Bootstrap command
  runcmd = module.bootstrap_token.join_cmd

  tags = {
    Environment = "production"
    Project     = "kamaji"
  }
}

Requirements

Name	Version
terraform	>= 1.0
azurerm	>= 3.0
cloudinit	>= 2.0

Providers

Name	Version
azurerm	>= 3.0
cloudinit	>= 2.0

Resources

azurerm_linux_virtual_machine_scale_set - Main VMSS resource
azurerm_network_security_group - Security group for nodes
azurerm_network_security_rule - Security rules
azurerm_monitor_autoscale_setting - Autoscaling configuration

Variables

Name	Description	Type	Default
`tenant_cluster_name`	Name of the tenant cluster	`string`	`"charlie"`
`pool_name`	Name of the node pool	`string`	`"default"`
`pool_size`	The size of the node pool	`number`	`3`
`pool_min_size`	The minimum size of the node pool	`number`	`1`
`pool_max_size`	The maximum size of the node pool	`number`	`9`
`azure_location`	Azure region where resources are created	`string`	`"italynorth"`
`azure_resource_group_name`	Name of the Azure resource group	`string`	`"kamaji"`
`azure_vnet_name`	Name of the Azure virtual network	`string`	`"kamaji-vnet"`
`azure_subnet_name`	Name of the Azure subnet	`string`	`"kamaji-subnet"`
`vm_size`	Size of the virtual machines	`string`	`"Standard_D2s_v3"`
`assign_public_ip`	Whether to assign public IP addresses to VMs	`bool`	`true`
`node_disk_size`	Disk size for each node in GB	`number`	`30`
`node_disk_type`	Storage account type for each node	`string`	`"Premium_LRS"`
`ssh_user`	SSH user for the nodes	`string`	`"ubuntu"`
`ssh_public_key_path`	Path to the SSH public key	`string`	`"~/.ssh/id_rsa.pub"`
`enable_autoscaling`	Enable automatic scaling based on CPU metrics	`bool`	`true`
`scale_out_cpu_threshold`	CPU threshold percentage to trigger scale out	`number`	`75`
`scale_in_cpu_threshold`	CPU threshold percentage to trigger scale in	`number`	`25`
`runcmd`	Command to run on the node at first boot time	`string`	`"echo 'Hello, World!'"`

Outputs

Name	Description
`vmss_details`	Virtual Machine Scale Set details
`autoscale_settings`	Autoscale settings details
`network_security_group`	Network Security Group details

Security Groups

The module creates a Network Security Group with the following rules:

Outbound: Allow all outbound traffic
SSH: Allow inbound SSH (port 22) from anywhere
Cluster Internal: Allow all traffic within the subnet

Scaling Behavior

This module supports both manual and automatic scaling modes:

Manual Scaling (`enable_autoscaling = false`)

Direct Control: Terraform directly manages VMSS instance count
pool_size Changes: Changing pool_size will update the VMSS immediately on terraform apply
No Lifecycle Rules: No ignore_changes applied to instances
Use Case: Predictable workloads requiring manual capacity control

Automatic Scaling (`enable_autoscaling = true`)

CPU-Based: Azure autoscaler manages instance count based on CPU metrics
Scale Out: When average CPU > 75% for 5 minutes
Scale In: When average CPU < 25% for 5 minutes
Cooldown: 1 minute between scaling actions
Default Capacity: pool_size sets the initial/default capacity
Lifecycle Protection: Terraform ignores instance count changes made by autoscaler

Instance Repair

Automatic instance repair is enabled by default with a 30-minute grace period for failed VMs.

README.md

Azure Node Pool Module

Features

Usage