Using Datascript to Redirect Traffic Based on HTTP Referer Header to certain pool.

Products

• VMware Avi Load Balancer

Issue/Introduction

• When handling HTTP requests, the Referer header can be used to identify the source of the request and ensure traffic is coming from a trusted domain.
• In some cases, using an Avi HTTP policy alone cannot fully achieve the required redirection logic. In such scenarios, a Datascript can be applied to implement fine-grained traffic routing based on the request URI and Referer header.

Resolution

• You can use a Datascript and attach it to the Virtual Service under:
  VS → Policies → Datascript → HTTP Request Event.

 

• Example Use Case:

• If the request URI ends with LoginDay.path

  • And the Referer header also ends with 5LoginDay.path → Redirect traffic to XFF Pool

  • Else → Redirect traffic to the Default Pool

 

Sample Datascript:

 

if path:sub(-string.len("LoginDay.path")) == "LoginDay.path" then
    if referer:sub(-string.len("5LoginDay.path")) == "5LoginDay.path" then
        avi.http.add_header("X-Debug", "REQ: LoginDay.path + Referer 5LoginDay.path → pool XFF")
        avi.pool.select("XFF")
        return
    else
        avi.http.add_header("X-Debug", "REQ: LoginDay.path + other Referer → pool Default")
        avi.pool.select("Default")
        return
    end
end