Callouts sample: body/header mutating sidestream #214
Description
A server that buffers header and body content, and sets headers based on body content.
- requires buffering the whole body
- requires FULL_DUPLEX_STREAMED mode, which requires supporting TRAILERS when upstream sends them (in this case, body chunks never have eos bit)
Some Envoy integration tests for full duplex:
- https://github.com/envoyproxy/envoy/blob/main/test/extensions/filters/http/ext_proc/ext_proc_integration_test.cc
- ServerWaitForBodyBeforeSendsHeaderRespDuplexStreamed
- ServerWaitForBodyAndTrailerBeforeSendsHeaderRespDuplexStreamedSmallBody