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Configure Request and Response Proxy Buffers

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Azure Application Gateway Standard v2 SKU supports buffering Requests (from clients) or Responses (from the backend servers). Based on the processing capabilities of the clients that interact with your Application Gateway, you can use these buffers to configure the speed of packet delivery.

Response Buffer

Application Gateway's Response buffer can collect all or parts of the response packets sent by the backend server, before delivering them to the clients. By default, the Response buffering is enabled on Application Gateway which is useful to accommodate slow clients. This setting allows you to conserve the backend TCP connections as they can be closed once Application Gateway receives complete response and work according to the client's processing speed. This way, your Application Gateway will continue to deliver the response as per client’s pace.

Request Buffer

In a similar way, Application Gateway's Request buffer can temporarily store the entire or parts of the request body, and then forward a larger upload request at once to the backend server. By default, Request buffering setting is enabled on Application Gateway and is useful to offload the processing function of re-assembling the smaller packets of data on the backend server.

Note

By default, both Request and Response buffers are enabled on your Application Gateway resource but you can choose to configure them separately. Further, the settings are applied at a resource level and cannot be managed separately for each listener.


You can keep either the Request or Response buffer, enabled or disable, based on your requirements and/or the observed performance of the client systems that communicate with your Application Gateway.


Warning

We strongly recommend that you test and evaluate the performance before rolling this out on the production gateways.

How to change the buffer settings?

You can change this setting by using the globalConfiguration property.

Azure CLI method

Response Buffer

az network application-gateway update --name <gw-name> --resource-group <rg-name> --set globalConfiguration.enableResponseBuffering=false

Request Buffer

 az network application-gateway update --name <gw-name> --resource-group <rg-name> --set globalConfiguration.enableRequestBuffering=false

ARM template method

{
   "$schema":"https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
   "contentVersion":"1.0.0.0",
   "parameters":{      
   },
   "variables":{      
   },
   "resources":[
      {
         "type":"Microsoft.Network/applicationGateways",
         "apiVersion":"xxx-xx-xx",
         "name":"[parameters('applicationGateways_xxxx_x_xx_name')]",
         "location":"eastus",
         "tags":{            
         },
         "identity":{      
         },
         "properties":{
            "globalConfiguration":{
               "enableRequestBuffering":false,
               "enableResponseBuffering":false
            }
         }
      }
   ]
}

For reference, visit Azure SDK for .NET

Limitations

  • API version 2020-01-01 or later should be used to configure buffers.
  • Currently, these changes are not supported through Portal and PowerShell.
  • Request buffering cannot be disabled if you are running the WAF SKU of Application Gateway. The WAF requires the full request to buffer as part of processing, therefore, even if you disable request buffering within Application Gateway the WAF will still buffer the request. Response buffering is not impacted by the WAF.