thrift: EncoderFilter and BidirectionalFilter support

[JuniorHsu]

Commit Message:
EncoderFilter and BidirectionalFilter support in thrift_proxy filter.

In this diff, the EncoderFilter and BidirectionalFilter support

• peek the metadata and content for encoding
• modify the metadata and content for encoding

Do not support

• pass through data separately for encode and decode, e.g., passThroughData in encoding but not passThroughData in decoding
• StopIteration in encoding (would intentionally crash)

Additional Description:
Risk Level: low
Testing: Unit test
Docs Changes:
Release Notes:
[Optional Fixes #Issue] #20497

[JuniorHsu]

Still need more tests and documentation but it would be good to have some early feedback.

cc @mattklein123 @zuercher @rgs1 @fishcakez

[rgs1]

Left an idea on how to potentially avoid some of the boilerplate that's needed.

[JuniorHsu]

Currently the connection manager and the upstream request won't expect the encoder filter would StopIteration
https://github.com/envoyproxy/envoy/blob/main/source/extensions/filters/network/thrift_proxy/conn_manager.cc#L213
https://github.com/envoyproxy/envoy/blob/c90728a183eab491f1603ecbbf45d23cab0d08d6/source/extensions/filters/network/thrift_proxy/router/upstream_request.cc#129
That is, if all the response data arrive, the upstream request would expect we got a final response synchronously.

Therefore I'd like to not supporting StopIteration (i.e., throw if the encoder filter returns StopIteration). I'll update the limitation in the summary

[JuniorHsu]

I'm trying to test if modification of values works (i.e., boolValue, byteValue, etc.)

But the stringValue passes the string_view, which indicates not to modify.

envoy/source/extensions/filters/network/thrift_proxy/decoder_events.h

Line 99 in 6931f18

virtual FilterStatus stringValue(absl::string_view value) PURE;

[JuniorHsu]

Ideally we could pass through data separately for encode and decode, e.g., passThroughData in encoding but not passThroughData in decoding.

request check

envoy/source/extensions/filters/network/thrift_proxy/conn_manager.cc

Line 191 in 6931f18

bool ConnectionManager::passthroughEnabled() const {

response check

envoy/source/extensions/filters/network/thrift_proxy/conn_manager.cc

Line 312 in 6931f18

bool ConnectionManager::ResponseDecoder::passthroughEnabled() const {

[alyssawilk]

@zuercher ping?

[zuercher]

@rgs1 did you have any other comments for this PR?

[rgs1]

This is looking good, thanks! Just two more questions.

[rgs1]

LGTM modulo one comment nit. Thanks!

[JuniorHsu]

@zuercher could you help to move this forward? thanks!

[JuniorHsu]

@alyssawilk Sorry for random ping. Any chance to move this forward to avoid keeping rebase on a 2K+ lines diff?
All the comments from @.zuercher and @.rgs1 are already addressed and @.rgs1 approved.
Thanks!