Option to enable envoy request or response headers separately

[lboynton]

Description:

Describe the desired behavior, what scenario it enables and how it
would be used.

I would like to be able to enable envoy request headers like x-envoy-original-path so that I see the original path for URL rewritten requests in traces and access logs. There is an option in CTP called enableEnvoyHeaders which does this. However, this also enables envoy response headers which I do not want to return to clients.

Would it be possible to have separate flags in CTP for enabling request or response headers?

[optional Relevant Links:]

Any extra documentation required to understand the issue.

Previous discussion here for context: #8477 (comment)

[zhaohuabing]

I think this would need change on the Envoy upstream: https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/filters/http/router/v3/router.proto#:~:text=suppress_envoy_headers

[zirain]

IIRC, this's not supported in envoy today.

	// Do not add any additional *x-envoy-* headers to requests or responses. This
	// only affects the :ref:`router filter generated *x-envoy-* headers
	// <config_http_filters_router_headers_set>`, other Envoy filters and the HTTP
	// connection manager may continue to set *x-envoy-* headers.
	SuppressEnvoyHeaders bool `protobuf:"varint,4,opt,name=suppress_envoy_headers,json=suppressEnvoyHeaders,proto3" json:"suppress_envoy_headers,omitempty"`