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Use two or more App Service Plan instances#

Reliability · App Service · Rule · 2020_06 · Important

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:

Azure Template snippet
{
    "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:

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

Configure with Azure Verified Modules

A pre-validated module supported by Microsoft is available from the Azure Bicep public registry. To reference the module, please use the following syntax:

br/public:avm/res/web/serverfarm:<version>

To use the latest version:

br/public:avm/res/web/serverfarm:0.3.0

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