add otel instrumentation (#581)

this change adds OTEL tracing to a few places

* Top-level application lifecycle (config/init/cleanup, main loop)
* http.sys requests

it also brings some otlptrace optimizations and dynamic configuration of tracing. OTLP tracing is currently always disabled

1 files changed, 88 insertions, 5 deletions

diff --git a/src/zenhttp/servers/httpsys.cpp b/src/zenhttp/servers/httpsys.cpp
index 7b02f95f1..87b66dcd1 100644
--- a/src/zenhttp/servers/httpsys.cpp
+++ b/src/zenhttp/servers/httpsys.cpp
@@ -15,6 +15,7 @@
 #include <zencore/timer.h>
 #include <zencore/trace.h>
 #include <zenhttp/packageformat.h>
+#include <zentelemetry/otlptrace.h>
 
 #include <EASTL/fixed_vector.h>
 
@@ -36,6 +37,41 @@ GetHttpsysTag()
 	return HttpsysTag;
 }
 
+static void
+GetAddressString(StringBuilderBase& OutString, const SOCKADDR* SockAddr, bool IncludePort = true)
+{
+	if (SockAddr)
+	{
+		// When a port is desired, use WSAAddressToStringA which includes the port.
+		if (IncludePort)
+		{
+			CHAR		AddrBuf[64] = {};
+			DWORD		AddrBufLen	= sizeof(AddrBuf);
+			const DWORD AddrLen		= (SockAddr->sa_family == AF_INET) ? sizeof(SOCKADDR_IN) : sizeof(SOCKADDR_IN6);
+
+			if (WSAAddressToStringA((LPSOCKADDR)SockAddr, AddrLen, nullptr, AddrBuf, &AddrBufLen) == 0)
+			{
+				OutString.Append(AddrBuf, AddrBufLen);
+				return;
+			}
+		}
+		else
+		{
+			// When port should be omitted, use getnameinfo with NI_NUMERICHOST to get only the numeric address.
+			CHAR	  HostBuf[64] = {};
+			const int SockLen	  = (SockAddr->sa_family == AF_INET) ? sizeof(SOCKADDR_IN) : sizeof(SOCKADDR_IN6);
+
+			if (getnameinfo((const SOCKADDR*)SockAddr, SockLen, HostBuf, (DWORD)sizeof(HostBuf), nullptr, 0, NI_NUMERICHOST) == 0)
+			{
+				OutString.Append(HostBuf, (DWORD)strlen(HostBuf));
+				return;
+			}
+		}
+	}
+
+	OutString.Append("unknown");
+}
+
 /**
  * @brief Windows implementation of HTTP server based on http.sys
  *
@@ -382,6 +418,8 @@ public:
 	virtual HttpSysRequestHandler* HandleCompletion(ULONG IoResult, ULONG_PTR NumberOfBytesTransferred) override;
 	void						   SuppressResponseBody();	// typically used for HEAD requests
 
+	inline int64_t GetResponseBodySize() const { return m_TotalDataSize; }
+
 private:
 	eastl::fixed_vector<HTTP_DATA_CHUNK, 16> m_HttpDataChunks;
 	uint64_t								 m_TotalDataSize	   = 0;	 // Sum of all chunk sizes
@@ -1605,6 +1643,27 @@ HttpSysTransaction::InvokeRequestHandler(HttpService& Service, IoBuffer Payload)
 
 	// Default request handling
 
+#	if ZEN_WITH_OTEL
+	std::string_view Verb = ToString(ThisRequest.RequestVerb());
+	std::string_view Uri  = ThisRequest.m_UriUtf8.ToView();
+
+	ExtendableStringBuilder<64> SpanName;
+	SpanName << Verb << " " << Uri;
+	otel::ScopedSpan HttpSpan(SpanName.ToView(), [&](otel::Span& Span) {
+		Span.AddAttribute("http.request.method"sv, Verb);
+		Span.AddAttribute("url.path"sv, Uri);
+		// FIXME: should be total size including headers etc according to spec
+		Span.AddAttribute("http.request.size"sv, static_cast<int64_t>(ThisRequest.ContentLength()));
+		Span.SetKind(otel::Span::Kind::kServer);
+
+		// client.address
+		const SOCKADDR*				SockAddr = ThisRequest.m_HttpTx.HttpRequest()->Address.pRemoteAddress;
+		ExtendableStringBuilder<64> ClientAddr;
+		GetAddressString(ClientAddr, SockAddr, /* IncludePort */ false);
+		Span.AddAttribute("client.address"sv, ClientAddr.ToView());
+	});
+#	endif
+
 	if (!HandlePackageOffers(Service, ThisRequest, m_PackageHandler))
 	{
 		Service.HandleRequest(ThisRequest);
@@ -1616,7 +1675,8 @@ HttpSysTransaction::InvokeRequestHandler(HttpService& Service, IoBuffer Payload)
 //////////////////////////////////////////////////////////////////////////
 
 HttpSysServerRequest::HttpSysServerRequest(HttpSysTransaction& Tx, HttpService& Service, IoBuffer PayloadBuffer)
-: m_HttpTx(Tx)
+: HttpServerRequest(Service)
+, m_HttpTx(Tx)
 , m_PayloadBuffer(std::move(PayloadBuffer))
 {
 	const HTTP_REQUEST* HttpRequestPtr = Tx.HttpRequest();
@@ -1626,16 +1686,16 @@ HttpSysServerRequest::HttpSysServerRequest(HttpSysTransaction& Tx, HttpService&
 
 	HttpContentType AcceptContentType = HttpContentType::kUnknownContentType;
 
+	WideToUtf8({(wchar_t*)HttpRequestPtr->CookedUrl.pAbsPath, gsl::narrow<size_t>(AbsPathLength)}, m_UriUtf8);
+
 	if (AbsPathLength >= PrefixLength)
 	{
 		// We convert the URI immediately because most of the code involved prefers to deal
 		// with utf8. This is overhead which I'd prefer to avoid but for now we just have
 		// to live with it
 
-		WideToUtf8({(wchar_t*)HttpRequestPtr->CookedUrl.pAbsPath + PrefixLength, gsl::narrow<size_t>(AbsPathLength - PrefixLength)},
-				   m_UriUtf8);
-
 		std::string_view UriSuffix8{m_UriUtf8};
+		UriSuffix8.remove_prefix(PrefixLength);
 
 		m_UriWithExtension = UriSuffix8;  // Retain URI with extension for user access
 		m_Uri			   = UriSuffix8;
@@ -1662,7 +1722,6 @@ HttpSysServerRequest::HttpSysServerRequest(HttpSysTransaction& Tx, HttpService&
 	}
 	else
 	{
-		m_UriUtf8.Reset();
 		m_Uri			   = {};
 		m_UriWithExtension = {};
 	}
@@ -1771,6 +1830,14 @@ HttpSysServerRequest::WriteResponse(HttpResponseCode ResponseCode)
 
 	m_NextCompletionHandler = Response;
 
+#	if ZEN_WITH_OTEL
+	if (otel::Span* ActiveSpan = otel::Span::GetCurrentSpan())
+	{
+		ActiveSpan->AddAttribute("http.response.body.size"sv, Response->GetResponseBodySize());
+		ActiveSpan->AddAttribute("http.response.status_code"sv, static_cast<int64_t>(ResponseCode));
+	}
+#	endif
+
 	SetIsHandled();
 }
 
@@ -1790,6 +1857,14 @@ HttpSysServerRequest::WriteResponse(HttpResponseCode ResponseCode, HttpContentTy
 
 	m_NextCompletionHandler = Response;
 
+#	if ZEN_WITH_OTEL
+	if (otel::Span* ActiveSpan = otel::Span::GetCurrentSpan())
+	{
+		ActiveSpan->AddAttribute("http.response.body.size"sv, Response->GetResponseBodySize());
+		ActiveSpan->AddAttribute("http.response.status_code"sv, static_cast<int64_t>(ResponseCode));
+	}
+#	endif
+
 	SetIsHandled();
 }
 
@@ -1810,6 +1885,14 @@ HttpSysServerRequest::WriteResponse(HttpResponseCode ResponseCode, HttpContentTy
 
 	m_NextCompletionHandler = Response;
 
+#	if ZEN_WITH_OTEL
+	if (otel::Span* ActiveSpan = otel::Span::GetCurrentSpan())
+	{
+		ActiveSpan->AddAttribute("http.response.body.size"sv, Response->GetResponseBodySize());
+		ActiveSpan->AddAttribute("http.response.status_code"sv, static_cast<int64_t>(ResponseCode));
+	}
+#	endif
+
 	SetIsHandled();
 }