envoy filter to intercept upstream response

[balaji srinivasan]

Hi,

I have written the ext_authz filter for envoy and have basic understanding of how envoy filters done. But now I want to filter the response coming back from the upstream. Specifically, I want to handle two things:

1. Intercept data/jsonBody coming from upstream and Filter/Modify the responseJsonBody based on some business rule before envoy sends back to downstream.

2. If upstream is down(when http response code 408-Timeout), I want to save the post-request to async-msg-que and send back a 202-Accepted back to downstream. This way, when the upstream comes back it will process pending post-request from it's async-msg-que.

Is there a existing filter I can use for these purpose or what is the right way to do this using envoy-proxy sidecar.

Thanks, Balaji