Use two or more App Service Plan instances

March 21, 2025 ยท View on GitHub

SYNOPSIS

App Service Plan should use a minimum number of instances for failover.

DESCRIPTION

App Services Plans provides a configurable number of instances that will run apps. When a single instance is configured your app may be temporarily unavailable during unplanned interruptions. In most circumstances, Azure will self heal faulty app service instances automatically. However during this time there may interruptions to your workload.

This rule does not apply to consumption or elastic App Services Plans.

RECOMMENDATION

Consider using an App Service Plan with at least two (2) instances.

EXAMPLES

Configure with Azure template

To deploy App Services Plans that pass this rule:

  • Set sku.capacity to 2 or more.

For example:

{
    "type": "Microsoft.Web/serverfarms",
    "apiVersion": "2021-01-15",
    "name": "[parameters('planName')]",
    "location": "[parameters('location')]",
    "sku": {
        "name": "S1",
        "tier": "Standard",
        "capacity": 2
    }
}

Configure with Bicep

To deploy App Services Plans that pass this rule:

  • Set sku.capacity to 2 or more.

For example:

resource appPlan 'Microsoft.Web/serverfarms@2021-01-15' = {
  name: planName
  location: location
  sku: {
    name: 'S1'
    tier: 'Standard'
    capacity: 2
  }
}