I tried setting up with envoy filter using the below code:

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: proxy-headers-lua
  namespace: default
spec:
  workloadSelector:
    labels:
      app: web
  configPatches:
    # The first patch adds the lua filter to the listener/http connection manager
  - applyTo: HTTP_FILTER
    match:
      context: SIDECAR_INBOUND
    patch:
      operation: INSERT_BEFORE
      value: # lua filter specification
       name: envoy.lua
       config:
         inlineCode: |
           function envoy_on_request(request_handle)
             body_size = request_handle:body():length()
             request_handle:headers():add("request-body-size", tostring(body_size))
             request_handle:httpCall(300000)
           end

but it doesn't seem to be taking affect. when i curl post request to web app with data > 2mb it throws http error 413