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Use Health Probes for Front Door backends#

Reliability · Front Door · Rule · 2021_03

Use health probes to check the health of each backend.

Description#

The health and performance of an application can degrade over time. Degradation might not be noticeable until the application fails.

Azure Front Door can use periodic health probes against backend endpoints to determine health status. When one or more backend in a pool is healthy traffic is routed to healthy endpoints only. If all endpoints in a pool is unhealthy Front Door sends the request to any enabled endpoint.

Health probes allow Front Door to select a backend endpoint able to respond to the request.

Recommendation#

Consider configuring and enabling a health probe for each Front Door backend.

Examples#

Configure with Azure template#

To deploy a Front Door resource that passes this rule:

  • Configure the properties.healthProbeSettings property of the originGroups sub-resource.

For example:

Azure Template snippet
{
  "type": "Microsoft.Cdn/profiles",
  "apiVersion": "2021-06-01",
  "name": "[parameters('name')]",
  "location": "Global",
  "sku": {
    "name": "Premium_AzureFrontDoor"
  }
},
{
  "type": "Microsoft.Cdn/profiles/originGroups",
  "apiVersion": "2021-06-01",
  "name": "[format('{0}/{1}', parameters('name'), parameters('name'))]",
  "properties": {
    "loadBalancingSettings": {
      "sampleSize": 4,
      "successfulSamplesRequired": 3
    },
    "healthProbeSettings": {
      "probePath": "/healthz",
      "probeRequestType": "HEAD",
      "probeProtocol": "Http",
      "probeIntervalInSeconds": 100
    }
  },
  "dependsOn": [
    "[parameters('name')]"
  ]
}

To deploy a Front Door resource that passes this rule:

  • Set each properties.healthProbeSettings[*].properties.enabledState property to Enabled.

For example:

Azure Template snippet
{
  "type": "Microsoft.Network/frontDoors",
  "apiVersion": "2021-06-01",
  "name": "[parameters('name')]",
  "location": "global",
  "properties": {
    "enabledState": "Enabled",
    "frontendEndpoints": "[variables('frontendEndpoints')]",
    "loadBalancingSettings": "[variables('loadBalancingSettings')]",
    "backendPools": "[variables('backendPools')]",
    "healthProbeSettings": [
      {
        "name": "[variables('healthProbeSettingsName')]",
        "properties": {
          "enabledState": "Enabled",
          "path": "/healthz",
          "protocol": "Http",
          "intervalInSeconds": 120,
          "healthProbeMethod": "HEAD"
        }
      }
    ],
    "routingRules": "[variables('routingRules')]"
  }
}

Configure with Bicep#

To deploy a Front Door resource that passes this rule:

  • Configure the properties.healthProbeSettings property of the originGroups sub-resource.

For example:

Azure Bicep snippet
resource afd_premium 'Microsoft.Cdn/profiles@2021-06-01' = {
  name: name
  location: 'Global'
  sku: {
    name: 'Premium_AzureFrontDoor'
  }
}

resource frontDoorOriginGroup 'Microsoft.Cdn/profiles/originGroups@2021-06-01' = {
  name: name
  parent: afd_premium
  properties: {
    loadBalancingSettings: {
      sampleSize: 4
      successfulSamplesRequired: 3
    }
    healthProbeSettings: {
      probePath: '/healthz'
      probeRequestType: 'HEAD'
      probeProtocol: 'Http'
      probeIntervalInSeconds: 100
    }
  }
}

To deploy a Front Door resource that passes this rule:

  • Set each properties.healthProbeSettings[*].properties.enabledState property to Enabled.

For example:

Azure Bicep snippet
resource afd_classic 'Microsoft.Network/frontDoors@2021-06-01' = {
  name: name
  location: 'global'
  properties: {
    enabledState: 'Enabled'
    frontendEndpoints: frontendEndpoints
    loadBalancingSettings: loadBalancingSettings
    backendPools: backendPools
    healthProbeSettings: [
      {
        name: healthProbeSettingsName
        properties: {
          enabledState: 'Enabled'
          path: '/healthz'
          protocol: 'Http'
          intervalInSeconds: 120
          healthProbeMethod: 'HEAD'
        }
      }
    ]
    routingRules: routingRules
  }
}

Configure with Azure CLI#

Azure CLI snippet
az network front-door probe update --front-door-name '<front_door>' -n '<probe_name>' -g '<resource_group>' --enabled 'Enabled' --path '/healthz'

Configure with Azure PowerShell#

Azure PowerShell snippet
$probeSetting = New-AzFrontDoorHealthProbeSettingObject -Name '<probe_name>' -EnabledState 'Enabled' -Path '/healthz'
Set-AzFrontDoor -Name '<front_door>' -ResourceGroupName '<resource_group>' -HealthProbeSetting $probeSetting
Last update: 2023-02-18

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