wasm: API to add tags to active span from wasm filter

api/wasm/cpp/doc/wasm_filter.md

@@ -675,6 +675,14 @@ method is effective when calling from
 Returns [WasmData](#wasmdata) pointer which
 holds the response body data.
 
+### activeSpanSetTag
+
+``` {.sourceCode .cpp}
+void activeSpanSetTag(StringView key, StringView value)
+```
+Sets a tag key and value in the active span of the request being
+processed by the filte.
+
 Metadata API
 ------------
 

api/wasm/cpp/proxy_wasm_api.h

@@ -169,6 +169,7 @@ struct Tuple3Hash {
 };
 
 using HeaderStringPairs = std::vector<std::pair<std::string, std::string>>;
+using SpanTagPairs = std::vector<std::pair<std::string, std::string>>;
 
 class GrpcCallHandlerBase {
 public:
@@ -781,6 +782,11 @@ inline WasmResult makeHttpCall(StringView uri, const HeaderStringPairs& request_
   return result;
 }
 
+// Tracing
+inline WasmResult activeSpanSetTag(StringView key, StringView value) {
+  return proxy_active_span_set_tag(key.data(), key.size(), value.data(), value.size());
+}
+
 // Low level metrics interface.
 
 inline WasmResult defineMetric(MetricType type, StringView name, uint32_t* metric_id) {

api/wasm/cpp/proxy_wasm_externs.h

@@ -164,6 +164,9 @@ extern "C" void proxy_on_grpc_trailing_metadata(uint32_t context_id, uint32_t to
 extern "C" void proxy_on_grpc_receive(uint32_t context_id, uint32_t token, uint32_t response_size);
 extern "C" void proxy_on_grpc_close(uint32_t context_id, uint32_t token, uint32_t status_code);
 
+extern "C" WasmResult proxy_active_span_set_tag(const char* key_ptr, size_t key_size, const char* value_ptr,
+                                         size_t value_size);
+
 // The stream/vm has completed.
 extern "C" uint32_t proxy_on_done(uint32_t context_id);
 // proxy_on_log occurs after proxy_on_done.

api/wasm/cpp/proxy_wasm_intrinsics.js

@@ -37,4 +37,5 @@ mergeInto(LibraryManager.library, {
     proxy_set_effective_context : function () {},
     proxy_done: function () {},
     proxy_call_foreign_function: function () {},
+    proxy_active_span_set_tag: function () {},
 });

source/extensions/common/wasm/context.cc

@@ -1073,6 +1073,15 @@ void Context::scriptLog(spdlog::level::level_enum level, absl::string_view messa
 // Connection
 bool Context::isSsl() { return decoder_callbacks_->connection()->ssl() != nullptr; }
 
+// Tracing
+void Context::activeSpanSetTag(absl::string_view key, absl::string_view value) {
+  if (!decoder_callbacks_) {
+    return;
+  }
+  Tracing::Span& span = decoder_callbacks_->activeSpan();
+  span.setTag(key, value);
+}
+
 //
 // Calls into the WASM code.
 //

source/extensions/common/wasm/context.h

@@ -330,6 +330,9 @@ class Context : public Logger::Loggable<Logger::Id::wasm>,
   // Connection
   virtual bool isSsl();
 
+  // Tracing
+  virtual void activeSpanSetTag(absl::string_view key, absl::string_view value);
+
   void addAfterVmCallAction(std::function<void()> f);
 
 protected:

source/extensions/common/wasm/exports.cc

@@ -1,3 +1,5 @@
+#include <iostream>
+
 #include "extensions/common/wasm/wasm.h"
 
 namespace Envoy {
@@ -778,6 +780,18 @@ Word log(void* raw_context, Word level, Word address, Word size) {
   return wasmResultToWord(WasmResult::Ok);
 }
 
+Word active_span_set_tag(void* raw_context, Word key_ptr, Word key_size, Word value_ptr,
+                         Word value_size) {
+  auto context = WASM_CONTEXT(raw_context);
+  auto key = context->wasmVm()->getMemory(key_ptr.u64_, key_size.u64_);
+  auto value = context->wasmVm()->getMemory(value_ptr.u64_, value_size.u64_);
+  if (!key || !value) {
+    return wasmResultToWord(WasmResult::InvalidMemoryAccess);
+  }
+  context->activeSpanSetTag(key.value(), value.value());
+  return wasmResultToWord(WasmResult::Ok);
+}
+
 } // namespace Exports
 } // namespace Wasm
 } // namespace Common

source/extensions/common/wasm/exports.h

@@ -77,6 +77,8 @@ Word set_effective_context(void* raw_context, Word context_id);
 Word done(void* raw_context);
 Word call_foreign_function(void* raw_context, Word function_name, Word function_name_size,
                            Word arguments, Word warguments_size, Word results, Word results_size);
+Word active_span_set_tag(void* raw_context, Word key_ptr, Word key_size, Word value_ptr,
+                         Word value_size);
 
 // Runtime environment functions exported from envoy to wasm.
 

source/extensions/common/wasm/null/wasm_api_impl.h

@@ -93,7 +93,7 @@ inline WasmResult proxy_set_shared_data(const char* key_ptr, size_t key_size, co
 }
 
 // SharedQueue
-// Note: Registering the same queue_name will overwrite the old registration while preseving any
+// Note: Registering the same queue_name will overwrite the old registration while preserving any
 // pending data. Consequently it should typically be followed by a call to
 // proxy_dequeue_shared_queue. Returns unique token for the queue.
 inline WasmResult proxy_register_shared_queue(const char* queue_name_ptr, size_t queue_name_size,
@@ -214,6 +214,13 @@ inline WasmResult proxy_grpc_send(uint64_t token, const char* message_ptr, size_
                                              WS(message_size), WS(end_stream)));
 }
 
+// Tracing
+inline WasmResult proxy_active_span_set_tag(const char* key_ptr, size_t key_size,
+                                            const char* value_ptr, size_t value_size) {
+  return wordToWasmResult(Exports::active_span_set_tag(current_context_, WR(key_ptr), WS(key_size),
+                                                       WR(value_ptr), WS(value_size)));
+}
+
 // Metrics
 // Returns a metric_id which can be used to report a metric. On error returns 0.
 inline WasmResult proxy_define_metric(MetricType type, const char* name_ptr, size_t name_size,

source/extensions/common/wasm/wasm.cc

@@ -206,6 +206,7 @@ void Wasm::registerCallbacks() {
   _REGISTER_PROXY(set_effective_context);
   _REGISTER_PROXY(done);
   _REGISTER_PROXY(call_foreign_function);
+  _REGISTER_PROXY(active_span_set_tag);
 #undef _REGISTER_PROXY
 }
 

test/extensions/filters/http/wasm/test_data/Makefile

@@ -1,3 +1,3 @@
-all: headers_cpp.wasm async_call_cpp.wasm metadata_cpp.wasm grpc_call_cpp.wasm shared_cpp.wasm queue_cpp.wasm root_id_cpp.wasm
+all: headers_cpp.wasm async_call_cpp.wasm metadata_cpp.wasm grpc_call_cpp.wasm shared_cpp.wasm queue_cpp.wasm root_id_cpp.wasm tracing_cpp.wasm
 
 include ../../../../../../api/wasm/cpp/Makefile.base_lite

test/extensions/filters/http/wasm/test_data/Makefile.docker_cpp_builder

@@ -1,6 +1,6 @@
 DOCKER_SDK=/external_sdk
 
-all: headers_cpp.wasm async_call_cpp.wasm metadata_cpp.wasm grpc_call_cpp.wasm shared_cpp.wasm queue_cpp.wasm http_callout_cpp.wasm grpc_callout_cpp.wasm
+all: headers_cpp.wasm async_call_cpp.wasm metadata_cpp.wasm grpc_call_cpp.wasm shared_cpp.wasm queue_cpp.wasm http_callout_cpp.wasm grpc_callout_cpp.wasm tracing_cpp.wasm
 	chown ${uid}.${gid} *.wasm
 
 include ${DOCKER_SDK}/Makefile.base_lite

test/extensions/filters/http/wasm/test_data/tracing_cpp.cc

@@ -0,0 +1,18 @@
+// NOLINT(namespace-envoy)
+#include <string>
+#include <unordered_map>
+
+#include "proxy_wasm_intrinsics.h"
+
+class ExampleContext : public Context {
+public:
+  explicit ExampleContext(uint32_t id, RootContext* root) : Context(id, root) {}
+
+  FilterHeadersStatus onRequestHeaders(uint32_t) override;
+};
+static RegisterContextFactory register_ExampleContext(CONTEXT_FACTORY(ExampleContext));
+
+FilterHeadersStatus ExampleContext::onRequestHeaders(uint32_t) {
+  activeSpanSetTag("tag_1", "tag_value_1");
+  return FilterHeadersStatus::Continue;
+}

test/extensions/filters/http/wasm/wasm_filter_test.cc

@@ -16,6 +16,7 @@
 #include "test/mocks/ssl/mocks.h"
 #include "test/mocks/stream_info/mocks.h"
 #include "test/mocks/thread_local/mocks.h"
+#include "test/mocks/tracing/mocks.h"
 #include "test/mocks/upstream/mocks.h"
 #include "test/test_common/environment.h"
 #include "test/test_common/printers.h"
@@ -149,6 +150,7 @@ class WasmHttpFilterTest : public testing::TestWithParam<std::string> {
   NiceMock<Http::MockStreamEncoderFilterCallbacks> encoder_callbacks_;
   NiceMock<Envoy::StreamInfo::MockStreamInfo> request_stream_info_;
   NiceMock<LocalInfo::MockLocalInfo> local_info_;
+  NiceMock<Tracing::MockSpan> active_span_;
   envoy::config::core::v3::Metadata listener_metadata_;
   TestRoot* root_context_ = nullptr;
   Config::DataSource::RemoteAsyncDataProviderPtr remote_data_provider_;
@@ -555,6 +557,18 @@ TEST_P(WasmHttpFilterTest, SharedQueue) {
   wasm_->wasm()->queueReady(root_context_->id(), token);
 }
 
+// Verifies if the tags have been added correctly.
+TEST_P(WasmHttpFilterTest, AddTagToActiveSpans) {
+  setupConfig(TestEnvironment::readFileToStringForTest(TestEnvironment::substitute(
+      "{{ test_rundir }}/test/extensions/filters/http/wasm/test_data/tracing_cpp.wasm")));
+  setupFilter();
+  EXPECT_CALL(decoder_callbacks_, activeSpan).WillRepeatedly(ReturnRef(active_span_));
+  EXPECT_CALL(active_span_, setTag(Eq("tag_1"), Eq("tag_value_1")));
+  Http::TestRequestHeaderMapImpl request_headers{{":path", "/"}};
+  EXPECT_EQ(Http::FilterHeadersStatus::Continue, filter_->decodeHeaders(request_headers, true));
+  filter_->onDestroy();
+}
+
 // Script using a root_id which is not registered.
 TEST_P(WasmHttpFilterTest, RootIdNotRegistered) {
   setupConfig(TestEnvironment::readFileToStringForTest(TestEnvironment::substitute(