Rule set actions

An Azure Front Door rule set consist of rules with a combination of match conditions and actions. This article provides a detailed description of actions you can use in a rule set. An action defines the behavior that gets applied to a request type that a match condition(s) identifies. In a rule set, a rule can have up to five actions. Front Door also supports server variable in a rule set action.

The following actions are available for use in a rule set:

Route configuration override

The route configuration override action is used to override the origin group or the caching configuration for the request. You can choose to override or honor the origin group configurations specified in the route. However, when you override the route configuration, you must configure caching. Otherwise, caching gets disabled for the request.

You can also override how files get cached for specific requests, including:

• Override the caching behavior specified by the origin.
• How query string parameters are used to generate the request's cache key.
• The time to live (TTL) value to control how long contents stay in cache.

Properties

When Override origin group is set to Yes, set the following properties:

When Caching is set to Enabled, set the following properties:

Examples

In this example, we route all matched requests to an origin group named MyOriginGroup, regardless of the configuration in the Front Door endpoint route.

{
  "name": "RouteConfigurationOverride",
  "parameters": {
    "originGroupOverride": {
      "originGroup": {
        "id": "/subscriptions/<subscription-id>/resourcegroups/<resource-group-name>/providers/Microsoft.Cdn/profiles/<profile-name>/originGroups/MyOriginGroup"
      },
      "forwardingProtocol": "MatchRequest"
    },
    "cacheConfiguration": null,
    "typeName": "DeliveryRuleRouteConfigurationOverrideActionParameters"
  }
}

{
  name: 'RouteConfigurationOverride'
  parameters: {
    originGroupOverride: {
      originGroup: {
        id: '/subscriptions/<subscription-id>/resourcegroups/<resource-group-name>/providers/Microsoft.Cdn/profiles/<profile-name>/originGroups/MyOriginGroup'
      }
      forwardingProtocol: 'MatchRequest'
    }
    cacheConfiguration: null
    typeName: 'DeliveryRuleRouteConfigurationOverrideActionParameters'
  }
}

In this example, we set the cache key to include a query string parameter named customerId. Compression is enabled, and the origin's caching policies are honored.

{
  "name": "RouteConfigurationOverride",
  "parameters": {
    "cacheConfiguration": {
      "queryStringCachingBehavior": "IncludeSpecifiedQueryStrings",
      "queryParameters": "customerId",
      "isCompressionEnabled": "Enabled",
      "cacheBehavior": "HonorOrigin",
      "cacheDuration": null
    },
    "originGroupOverride": null,
    "typeName": "DeliveryRuleRouteConfigurationOverrideActionParameters"
  }
}

{
  name: 'RouteConfigurationOverride'
  parameters: {
    cacheConfiguration: {
      queryStringCachingBehavior: 'IncludeSpecifiedQueryStrings'
      queryParameters: 'customerId'
      isCompressionEnabled: 'Enabled'
      cacheBehavior: 'HonorOrigin'
      cacheDuration: null
    }
    originGroupOverride: null
    typeName: 'DeliveryRuleRouteConfigurationOverrideActionParameters'
  }
}

In this example, we override the cache expiration to 6 hours for matched requests that don't specify a cache duration already. Front Door ignores the query string when it determines the cache key, and compression is enabled.

{
  "name": "RouteConfigurationOverride",
  "parameters": {
    "cacheConfiguration": {
      "queryStringCachingBehavior": "IgnoreQueryString",
      "cacheBehavior": "OverrideIfOriginMissing",
      "cacheDuration": "0.06:00:00",
    },
    "originGroupOverride": null,
    "typeName": "DeliveryRuleRouteConfigurationOverrideActionParameters"
  }
}

{
  name: 'RouteConfigurationOverride'
  parameters: {
    cacheConfiguration: {
      queryStringCachingBehavior: 'IgnoreQueryString'
      cacheBehavior: 'OverrideIfOriginMissing'
      cacheDuration: '0.06:00:00'
    }
    originGroupOverride: null
    typeName: 'DeliveryRuleRouteConfigurationOverrideActionParameters'
  }
}

Modify request header

Use the modify request header action to modify the headers in the request when it's sent to your origin.

Properties

Example

In this example, we append the value AdditionalValue to the MyRequestHeader request header. If the origin set the response header to a value of ValueSetByClient, then after this action is applied, the request header would have a value of ValueSetByClientAdditionalValue.

{
  "name": "ModifyRequestHeader",
  "parameters": {
    "headerAction": "Append",
    "headerName": "MyRequestHeader",
    "value": "AdditionalValue",
    "typeName": "DeliveryRuleHeaderActionParameters"
  }
}

{
  name: 'ModifyRequestHeader'
  parameters: {
    headerAction: 'Append'
    headerName: 'MyRequestHeader'
    value: 'AdditionalValue'
    typeName: 'DeliveryRuleHeaderActionParameters'
  }
}

Modify response header

Use the modify response header action to modify headers that are present in responses before they're returned to your clients.

Properties

Example

In this example, we delete the header with the name X-Powered-By from the responses before they're returned to the client.

{
  "name": "ModifyResponseHeader",
  "parameters": {
    "headerAction": "Delete",
    "headerName": "X-Powered-By",
    "typeName": "DeliveryRuleHeaderActionParameters"
  }
}

{
  name: 'ModifyResponseHeader'
  parameters: {
    headerAction: 'Delete'
    headerName: 'X-Powered-By'
    typeName: 'DeliveryRuleHeaderActionParameters'
  }
}

URL redirect

Use the URL redirect action to redirect clients to a new URL. Clients are sent a redirection response from Front Door. Azure Front Door supports dynamic capture of URL path with {url_path:seg#} server variable, and converts URL path to lowercase or uppercase with {url_path.tolower} or {url_path.toupper}. For more information, see Server variables.

Properties

Example

In this example, we redirect the request to https://contoso.com/exampleredirection?clientIp={client_ip}, while preserving the fragment. An HTTP Temporary Redirect (307) is used. The IP address of the client is used in place of the {client_ip} token within the URL by using the client_ip server variable.

{
  "name": "UrlRedirect",
  "parameters": {
    "redirectType": "TemporaryRedirect",
    "destinationProtocol": "Https",
    "customHostname": "contoso.com",
    "customPath": "/exampleredirection",
    "customQueryString": "clientIp={client_ip}",
    "typeName": "DeliveryRuleUrlRedirectActionParameters"
  }
}

{
  name: 'UrlRedirect'
  parameters: {
    redirectType: 'TemporaryRedirect'
    destinationProtocol: 'Https'
    customHostname: 'contoso.com'
    customPath: '/exampleredirection'
    customQueryString: 'clientIp={client_ip}'
    typeName: 'DeliveryRuleUrlRedirectActionParameters'
  }
}

URL rewrite

Use the URL rewrite action to rewrite the path of a request that's en route to your origin. Azure Front Door supports dynamic capture of URL path with {url_path:seg#} server variable, and converts URL path to lowercase or uppercase with {url_path.tolower} or {url_path.toupper}. For more information, see Server variables.

Properties

Example

In this example, we rewrite all requests to the path /redirection, and don't preserve the remainder of the path.

{
  "name": "UrlRewrite",
  "parameters": {
    "sourcePattern": "/",
    "destination": "/redirection",
    "preserveUnmatchedPath": false,
    "typeName": "DeliveryRuleUrlRewriteActionParameters"
  }
}

{
  name: 'UrlRewrite'
  parameters: {
    sourcePattern: '/'
    destination: '/redirection'
    preserveUnmatchedPath: false
    typeName: 'DeliveryRuleUrlRewriteActionParameters'
  }
}

In Azure Front Door (classic), a Rules engine can consist up to 25 rules containing matching conditions and associated actions. This article provides a detailed description of each action you can define in a rule.

An action defines the behavior that gets applied to the request type that matches the condition or set of match conditions. In the Rules engine configuration, a rule can have up to 10 matching conditions and 5 actions. You can only have one Override Routing Configuration action in a single rule.

The following actions are available to use in Rules engine configuration.

Modify request header

Use these actions to modify headers that are present in requests sent to your backend.

Required fields

Modify response header

Use these actions to modify headers that are present in responses returned to your clients.

Required fields

Route configuration overrides

Route Type: Redirect

Use these actions to redirect clients to a new URL.

Required fields

Route Type: Forward

Use these actions to forward clients to a new URL. These actions also contain sub actions for URL rewrites and caching.

URL rewrite

Use this setting to configure an optional Custom Forwarding Path to use when constructing the request to forward to the backend.

Caching

Use these settings to control how files get cached for requests that contain query strings. Whether to cache your content based on all parameters or on selected parameters. You can use these settings to overwrite the time to live (TTL) value to control how long contents stay in cache. To force caching as an action, set the caching field to "Enabled." When you force caching, the following options appear: