External API calls using Istio EnvoyFilter/WasmPlugin

Hi Team,

I am intercepting API calls via my egress gateway using Envoy filter (or WasmPlugin) and then

  1. Trying to make an external API call via Envoy filter (or WasmPlugin) to fetch some data
  2. I created a ServiceEntry for that domain and routing via “outbound|443||external-domain-name”
  3. Update the intercepted API call’s header/body and continue the request

The issue which I am facing is that I am getting 503/504 error code but then I make a curl request from inside the kubernetes pod the external API call works fine and returns the expected 200 response code.

Hence I wanted to know if we can make calls to external service using the Envoy Filter (or WasmPlugin) and if we can make then how do we make it.