Containers & Kubernetes Security Baselines

resource "azurerm_kubernetes_cluster" "main" {
  name                = "aks-prod-001"
  resource_group_name = azurerm_resource_group.aks.name
  location            = azurerm_resource_group.aks.location
  dns_prefix          = "aks-prod"
  kubernetes_version  = "1.29"

  # NS: Private cluster — API server not exposed to internet
  private_cluster_enabled = true

  # IM-1: Entra ID RBAC (disable local accounts)
  local_account_disabled = true
  azure_active_directory_role_based_access_control {
    azure_rbac_enabled     = true
    managed                = true
    admin_group_object_ids = [azuread_group.aks_admins.object_id]
  }

  # IM-3: Workload Identity for pod-level Entra auth
  oidc_issuer_enabled       = true
  workload_identity_enabled = true

  # NS: Azure CNI Overlay for network policies
  network_profile {
    network_plugin      = "azure"
    network_plugin_mode = "overlay"
    network_policy      = "calico"              # Kubernetes network policies
    service_cidr        = "172.16.0.0/16"
    dns_service_ip      = "172.16.0.10"
  }

  # System node pool
  default_node_pool {
    name                = "system"
    vm_size             = "Standard_D4s_v5"
    node_count          = 3
    vnet_subnet_id      = azurerm_subnet.aks_nodes.id
    zones               = ["1", "2", "3"]
    os_sku              = "AzureLinux"           # Minimal attack surface
    temporary_name_for_rotation = "systemtemp"

    upgrade_settings {
      max_surge = "33%"
    }
  }

  # PV: Auto-upgrade channel
  automatic_channel_upgrade = "stable"
  node_os_channel_upgrade   = "NodeImage"

  # DP: Secrets Store CSI Driver for Key Vault
  key_vault_secrets_provider {
    secret_rotation_enabled  = true
    secret_rotation_interval = "2m"
  }

  # PV: Azure Policy add-on (Gatekeeper)
  azure_policy_enabled = true

  # LT: Defender profile
  microsoft_defender {
    log_analytics_workspace_id = azurerm_log_analytics_workspace.sentinel.id
  }

  # LT: OMS Agent for Container Insights
  oms_agent {
    log_analytics_workspace_id = azurerm_log_analytics_workspace.sentinel.id
  }

  identity {
    type = "SystemAssigned"
  }

  maintenance_window_auto_upgrade {
    frequency   = "Weekly"
    interval    = 1
    day_of_week = "Sunday"
    start_time  = "02:00"
    duration    = 4
  }
}

# ACR — Azure Container Registry

# ACR with private endpoint and image scanning
resource "azurerm_container_registry" "main" {
  name                = "acrprod001"
  resource_group_name = azurerm_resource_group.aks.name
  location            = azurerm_resource_group.aks.location
  sku                 = "Premium"               # Required for PE and geo-replication

  # NS: Disable public access
  public_network_access_enabled = false

  # PV: Content trust for signed images
  trust_policy_enabled = true

  # PV: Quarantine policy for unscanned images
  quarantine_policy_enabled = true
}

# NS: Private endpoint for ACR
resource "azurerm_private_endpoint" "acr" {
  name                = "pe-acr-prod"
  location            = azurerm_resource_group.aks.location
  resource_group_name = azurerm_resource_group.aks.name
  subnet_id           = azurerm_subnet.private_endpoints.id

  private_service_connection {
    name                           = "psc-acr-prod"
    private_connection_resource_id = azurerm_container_registry.main.id
    subresource_names              = ["registry"]
    is_manual_connection           = false
  }
}

# LT-3: AKS Diagnostic Settings
resource "azurerm_monitor_diagnostic_setting" "aks" {
  name                       = "diag-aks-prod"
  target_resource_id         = azurerm_kubernetes_cluster.main.id
  log_analytics_workspace_id = azurerm_log_analytics_workspace.sentinel.id

  enabled_log { category = "kube-apiserver" }
  enabled_log { category = "kube-audit-admin" }
  enabled_log { category = "kube-controller-manager" }
  enabled_log { category = "guard" }

  metric { category = "AllMetrics" }
}