Revert "http2: removes environment variable-triggered nghttp2 logging (…

…envoyproxy#34354)"

This reverts commit 14cd80f.

Signed-off-by: Yan Avlasov <yavlasov@google.com>

source/common/http/http2/BUILD

@@ -65,6 +65,18 @@ envoy_cc_library(
     ],
 )
 
+# Separate library for some nghttp2 setup stuff to avoid having tests take a
+# dependency on everything in codec_lib.
+envoy_cc_library(
+    name = "nghttp2_lib",
+    srcs = ["nghttp2.cc"],
+    hdrs = ["nghttp2.h"],
+    external_deps = ["nghttp2"],
+    deps = [
+        "//source/common/common:minimal_logger_lib",
+    ],
+)
+
 envoy_cc_library(
     name = "conn_pool_lib",
     srcs = ["conn_pool.cc"],

source/common/http/http2/nghttp2.cc

@@ -0,0 +1,35 @@
+#include "source/common/http/http2/nghttp2.h"
+
+#include "source/common/common/logger.h"
+
+// nghttp2 fails to convey the POSIX ssize_t declaration
+// that Microsoft declines to implement. Pick up a valid
+// ssize_t declaration for win32 in our platform.h
+#include "envoy/common/platform.h"
+
+#include "nghttp2/nghttp2.h"
+
+namespace Envoy {
+namespace Http {
+namespace Http2 {
+
+void initializeNghttp2Logging() {
+  // When ENVOY_NGHTTP2_TRACE is set, we install a debug logger, to prevent nghttp2
+  // logging directly to stdout at -l trace.
+  nghttp2_set_debug_vprintf_callback([](const char* format, va_list args) {
+    if (std::getenv("ENVOY_NGHTTP2_TRACE") != nullptr) {
+      char buf[2048];
+      const int n = ::vsnprintf(buf, sizeof(buf), format, args);
+      // nghttp2 inserts new lines, but we also insert a new line in the ENVOY_LOG
+      // below, so avoid double \n.
+      if (n >= 1 && static_cast<size_t>(n) < sizeof(buf) && buf[n - 1] == '\n') {
+        buf[n - 1] = '\0';
+      }
+      ENVOY_LOG_TO_LOGGER(Logger::Registry::getLog(Logger::Id::http2), trace, "nghttp2: {}", buf);
+    }
+  });
+}
+
+} // namespace Http2
+} // namespace Http
+} // namespace Envoy

source/common/http/http2/nghttp2.h

@@ -0,0 +1,14 @@
+#pragma once
+
+namespace Envoy {
+namespace Http {
+namespace Http2 {
+
+/**
+ * Setup nghttp2 trace-level logging for when debugging.
+ */
+void initializeNghttp2Logging();
+
+} // namespace Http2
+} // namespace Http
+} // namespace Envoy

source/exe/BUILD

@@ -215,6 +215,7 @@ envoy_cc_library(
     deps = [
         "//source/common/common:assert_lib",
         "//source/common/event:libevent_lib",
+        "//source/common/http/http2:nghttp2_lib",
         "//source/common/network/dns_resolver:dns_factory_util_lib",
         "//source/server:proto_descriptors_lib",
     ],

source/exe/process_wide.cc

@@ -4,6 +4,7 @@
 
 #include "source/common/common/assert.h"
 #include "source/common/event/libevent.h"
+#include "source/common/http/http2/nghttp2.h"
 #include "source/server/proto_descriptors.h"
 
 namespace Envoy {
@@ -37,6 +38,7 @@ ProcessWide::ProcessWide(bool validate_proto_descriptors) {
 #else
     UNREFERENCED_PARAMETER(validate_proto_descriptors);
 #endif
+    Http::Http2::initializeNghttp2Logging();
 
     // We do not initialize Google gRPC here -- we instead instantiate
     // Grpc::GoogleGrpcContext in MainCommon immediately after instantiating

test/per_file_coverage.sh

@@ -10,7 +10,7 @@ declare -a KNOWN_LOW_COVERAGE=(
 "source/common/crypto:95.5"
 "source/common/event:95.1" # Emulated edge events guards don't report LCOV
 "source/common/filesystem/posix:96.2" # FileReadToEndNotReadable fails in some env; createPath can't test all failure branches.
-"source/common/http/http2:96.0"
+"source/common/http/http2:95.9"
 "source/common/json:94.6"
 "source/common/matcher:94.4"
 "source/common/memory:73.6" # tcmalloc code path is not enabled in coverage build, only gperf tcmalloc, see PR#32589