http: add headers via local reply mapper

[Augustyniak]

Add an option for local reply mapper to add HTTP headers to local responses.

Commit Message:
Additional Description:
Risk Level: Low
Testing: Added unit tests and updated integration tests
Docs Changes: Updated
Release Notes: Updated
Fixes #11707

[repokitteh-read-only]

CC @envoyproxy/api-shepherds: Your approval is needed for changes made to api/envoy/.
CC @envoyproxy/api-watchers: FYI only for changes made to api/envoy/.

🐱

Caused by: #12093 was opened by Augustyniak.

see: more, trace.

[htuch]

/lgtm api

[Augustyniak]

I don’t think that envoy-presubmit (Linux-x64 tsan) job’s failure has anything to do with my changes here 🤔

[Augustyniak]

@htuch can you re-approve pls? I needed to push a small doc string update in one of the proto files.

[mattklein123]

Thanks looks great with a small comment.

/wait

[mattklein123]

I would probably remove this. The limit seems somewhat arbitrary.

[htuch]

We have these limits in other places for heads to add. I think it was put in for fuzzing.

[mattklein123]

I see, OK. Sounds good.

[Augustyniak]

Yes, this is why I added this requirement - I checked other places where the list of headers was defined and basically all of them had this limitation.

[Augustyniak]

I needed to merge master and push due to the conflict in current.rst file.

[Augustyniak]

I’m seeing the following error (I needed to merge master due to a conflict in current.rst file):

clang toolchain with libc++ configured
fix_format...
ERROR: Codecs are not synced: ./source/common/http/http2/codec_impl.cc does not match ./source/common/http/http2/codec_impl_legacy.cc. Update codec implementations to sync and/or update the diff manually to:
--- 
+++ 
@@ -1,4 +1,4 @@
-#include "common/http/http2/codec_impl.h"
+#include "common/http/http2/codec_impl_legacy.h"
 
 #include <cstdint>
 #include <memory>
@@ -25,6 +25,7 @@
 
 namespace Envoy {
 namespace Http {
+namespace Legacy {
 namespace Http2 {
 
 class Http2ResponseCodeDetailValues {
@@ -52,6 +53,9 @@
 };
 
 using Http2ResponseCodeDetails = ConstSingleton<Http2ResponseCodeDetailValues>;
+using Http::Http2::CodecStats;
+using Http::Http2::MetadataDecoder;
+using Http::Http2::MetadataEncoder;
 
 bool Utility::reconstituteCrumbledCookies(const HeaderString& key, const HeaderString& value,
                                           HeaderString& cookies) {
@@ -492,7 +496,7 @@
       max_headers_count_(max_headers_count),
       per_stream_buffer_limit_(http2_options.initial_stream_window_size().value()),

and I’m not sure how it’s related to my PR. I can update the content of the aforementioned file ^ but I’m not sure whether I should be doing this 🤔 @mattklein123 am I missing something here?

[Augustyniak]

I think that merging #12142 should help to get rid of the error I mentioned in my message above.

[Augustyniak]

@mattklein123 @htuch After a few merges of master it’s green again and ready to be merged.