App Service Plan should enable zone redundancy

Medium Azure General serverfarms-app-service-plan-enable

Applies to

Microsoft.Web/serverfarms

What CGPulse checks

A resource passes this rule when zoneRedundant must equal true. Anything else is reported as a finding with the evaluated property value attached as evidence.

How to fix it

Configure zone-redundant high availability to protect against zone failures. In Azure Portal: App Service Plan > Scale up > select zone-redundant tier. See: https://learn.microsoft.com/en-us/azure/app-service/overview-hosting-plans

Careful: Zone redundancy requires Premium v2/v3 tier and cannot be changed in-place. Requires creating a new plan and migrating apps

CLI

az appservice plan show --ids "{id}" --query "zoneRedundant" -o tsv

Bicep

// Zone redundancy requires a new App Service Plan with Premium v2/v3 SKU

resource appServicePlan 'Microsoft.Web/serverfarms@2023-12-01' = {{
  name: '{name}'
  location: resourceGroup().location
  sku: {{
    name: 'P1v3'
    tier: 'PremiumV3'
    capacity: 3
  }}
  properties: {{
    zoneRedundant: true
  }}
}}

// Migrate existing apps to the new zone-redundant plan

Terraform

# Zone redundancy requires creating a new plan (cannot enable on existing)
resource "azurerm_service_plan" "{name}" {
  name                = "{name}"
  resource_group_name = "{rg}"
  location            = var.location
  os_type             = "Linux"
  sku_name            = "P1v3"
  zone_balancing_enabled = true
  worker_count           = 3
}

Compliance frameworks

Cloud Security: Azure Foundations

Vendor documentation

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