nghttpx: Add access log variable for backend host and port

Use $backend_host and $backend_port.  $backend_host is backend host
name given in --backend option.  It could be a path to UNIX domain
socket.

gennghttpxfun.py

@@ -152,6 +152,8 @@ LOGVARS = [
     "ssl_protocol",
     "ssl_session_id",
     "ssl_session_reused",
+    "backend_host",
+    "backend_port",
 ]
 
 if __name__ == '__main__':

src/shrpx.cc

@@ -2082,6 +2082,10 @@ Logging:
               * $ssl_session_id: session ID for SSL/TLS connection.
               * $ssl_session_reused:  "r"   if  SSL/TLS   session  was
                 reused.  Otherwise, "."
+              * $backend_host:  backend  host   used  to  fulfill  the
+                request.  "-" if backend host is not available.
+              * $backend_port:  backend  port   used  to  fulfill  the
+                request.  "-" if backend host is not available.
 
               The  variable  can  be  enclosed  by  "{"  and  "}"  for
               disambiguation (e.g., ${remote_addr}).

src/shrpx_api_downstream_connection.cc

@@ -301,9 +301,10 @@ void APIDownstreamConnection::on_upstream_change(Upstream *uptream) {}
 
 bool APIDownstreamConnection::poolable() const { return false; }
 
-DownstreamAddrGroup *
+const std::shared_ptr<DownstreamAddrGroup> &
 APIDownstreamConnection::get_downstream_addr_group() const {
-  return nullptr;
+  static std::shared_ptr<DownstreamAddrGroup> s;
+  return s;
 }
 
 DownstreamAddr *APIDownstreamConnection::get_addr() const { return nullptr; }

src/shrpx_api_downstream_connection.h

@@ -54,7 +54,8 @@ public:
   // true if this object is poolable.
   virtual bool poolable() const;
 
-  virtual DownstreamAddrGroup *get_downstream_addr_group() const;
+  virtual const std::shared_ptr<DownstreamAddrGroup> &
+  get_downstream_addr_group() const;
   virtual DownstreamAddr *get_addr() const;
 
   int send_reply(unsigned int http_status, int api_status);

src/shrpx_client_handler.cc

@@ -643,7 +643,7 @@ void ClientHandler::pool_downstream_connection(
 
   dconn->set_client_handler(nullptr);
 
-  auto group = dconn->get_downstream_addr_group();
+  auto &group = dconn->get_downstream_addr_group();
 
   if (LOG_ENABLED(INFO)) {
     CLOG(INFO, this) << "Pooling downstream connection DCONN:" << dconn.get()
@@ -1143,7 +1143,8 @@ void ClientHandler::write_accesslog(Downstream *downstream) {
   upstream_accesslog(
       get_config()->logging.access.format,
       LogSpec{
-          downstream, StringRef{ipaddr_}, http2::to_method_string(req.method),
+          downstream, downstream->get_addr(), StringRef{ipaddr_},
+          http2::to_method_string(req.method),
 
           req.method == HTTP_CONNECT
               ? StringRef(req.authority)
@@ -1176,7 +1177,7 @@ void ClientHandler::write_accesslog(int major, int minor, unsigned int status,
 
   upstream_accesslog(get_config()->logging.access.format,
                      LogSpec{
-                         nullptr, StringRef(ipaddr_),
+                         nullptr, nullptr, StringRef(ipaddr_),
                          StringRef::from_lit("-"), // method
                          StringRef::from_lit("-"), // path,
                          StringRef(alpn_), nghttp2::ssl::get_tls_session_info(

src/shrpx_config.cc

@@ -434,6 +434,14 @@ LogFragmentType log_var_lookup_token(const char *name, size_t namelen) {
         return SHRPX_LOGF_SSL_PROTOCOL;
       }
       break;
+    case 't':
+      if (util::strieq_l("backend_hos", name, 11)) {
+        return SHRPX_LOGF_BACKEND_HOST;
+      }
+      if (util::strieq_l("backend_por", name, 11)) {
+        return SHRPX_LOGF_BACKEND_PORT;
+      }
+      break;
     }
     break;
   case 14:

src/shrpx_downstream.cc

@@ -124,6 +124,7 @@ Downstream::Downstream(Upstream *upstream, MemchunkPool *mcpool,
       response_buf_(mcpool),
       upstream_(upstream),
       blocked_link_(nullptr),
+      addr_(nullptr),
       num_retry_(0),
       stream_id_(stream_id),
       assoc_stream_id_(-1),
@@ -943,4 +944,13 @@ void Downstream::add_rcbuf(nghttp2_rcbuf *rcbuf) {
   rcbufs_.push_back(rcbuf);
 }
 
+void Downstream::set_downstream_addr_group(
+    const std::shared_ptr<DownstreamAddrGroup> &group) {
+  group_ = group;
+}
+
+void Downstream::set_addr(const DownstreamAddr *addr) { addr_ = addr; }
+
+const DownstreamAddr *Downstream::get_addr() const { return addr_; }
+
 } // namespace shrpx

src/shrpx_downstream.h

@@ -49,6 +49,8 @@ namespace shrpx {
 class Upstream;
 class DownstreamConnection;
 struct BlockedLink;
+struct DownstreamAddrGroup;
+struct DownstreamAddr;
 
 class FieldStore {
 public:
@@ -382,6 +384,12 @@ public:
 
   void add_rcbuf(nghttp2_rcbuf *rcbuf);
 
+  void
+  set_downstream_addr_group(const std::shared_ptr<DownstreamAddrGroup> &group);
+  void set_addr(const DownstreamAddr *addr);
+
+  const DownstreamAddr *get_addr() const;
+
   enum {
     EVENT_ERROR = 0x1,
     EVENT_TIMEOUT = 0x2,
@@ -429,6 +437,10 @@ private:
 
   // only used by HTTP/2 or SPDY upstream
   BlockedLink *blocked_link_;
+  // The backend address used to fulfill this request.  These are for
+  // logging purpose.
+  std::shared_ptr<DownstreamAddrGroup> group_;
+  const DownstreamAddr *addr_;
   // How many times we tried in backend connection
   size_t num_retry_;
   // The stream ID in frontend connection

src/shrpx_downstream_connection.h

@@ -61,7 +61,8 @@ public:
   // true if this object is poolable.
   virtual bool poolable() const = 0;
 
-  virtual DownstreamAddrGroup *get_downstream_addr_group() const = 0;
+  virtual const std::shared_ptr<DownstreamAddrGroup> &
+  get_downstream_addr_group() const = 0;
   virtual DownstreamAddr *get_addr() const = 0;
 
   void set_client_handler(ClientHandler *client_handler);

src/shrpx_health_monitor_downstream_connection.cc

@@ -95,9 +95,10 @@ void HealthMonitorDownstreamConnection::on_upstream_change(Upstream *uptream) {}
 
 bool HealthMonitorDownstreamConnection::poolable() const { return false; }
 
-DownstreamAddrGroup *
+const std::shared_ptr<DownstreamAddrGroup> &
 HealthMonitorDownstreamConnection::get_downstream_addr_group() const {
-  return nullptr;
+  static std::shared_ptr<DownstreamAddrGroup> s;
+  return s;
 }
 
 DownstreamAddr *HealthMonitorDownstreamConnection::get_addr() const {

src/shrpx_health_monitor_downstream_connection.h

@@ -54,7 +54,8 @@ public:
   // true if this object is poolable.
   virtual bool poolable() const;
 
-  virtual DownstreamAddrGroup *get_downstream_addr_group() const;
+  virtual const std::shared_ptr<DownstreamAddrGroup> &
+  get_downstream_addr_group() const;
   virtual DownstreamAddr *get_addr() const;
 };
 

src/shrpx_http2_downstream_connection.cc

@@ -538,7 +538,7 @@ int Http2DownstreamConnection::on_timeout() {
   return submit_rst_stream(downstream_, NGHTTP2_NO_ERROR);
 }
 
-DownstreamAddrGroup *
+const std::shared_ptr<DownstreamAddrGroup> &
 Http2DownstreamConnection::get_downstream_addr_group() const {
   return http2session_->get_downstream_addr_group();
 }

src/shrpx_http2_downstream_connection.h

@@ -64,7 +64,8 @@ public:
   // migrate to another Http2Session object.
   virtual bool poolable() const { return false; }
 
-  virtual DownstreamAddrGroup *get_downstream_addr_group() const;
+  virtual const std::shared_ptr<DownstreamAddrGroup> &
+  get_downstream_addr_group() const;
   virtual DownstreamAddr *get_addr() const;
 
   int send();

src/shrpx_http2_session.cc

@@ -976,6 +976,10 @@ int on_response_headers(Http2Session *http2session, Downstream *downstream,
   resp.http_major = 2;
   resp.http_minor = 0;
 
+  downstream->set_downstream_addr_group(
+      http2session->get_downstream_addr_group());
+  downstream->set_addr(http2session->get_addr());
+
   if (LOG_ENABLED(INFO)) {
     std::stringstream ss;
     for (auto &nv : nva) {
@@ -2126,8 +2130,9 @@ bool Http2Session::max_concurrency_reached(size_t extra) const {
                  session_, NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS);
 }
 
-DownstreamAddrGroup *Http2Session::get_downstream_addr_group() const {
-  return group_.get();
+const std::shared_ptr<DownstreamAddrGroup> &
+Http2Session::get_downstream_addr_group() const {
+  return group_;
 }
 
 void Http2Session::add_to_avail_freelist() {

src/shrpx_http2_session.h

@@ -162,7 +162,7 @@ public:
 
   DownstreamAddr *get_addr() const;
 
-  DownstreamAddrGroup *get_downstream_addr_group() const;
+  const std::shared_ptr<DownstreamAddrGroup> &get_downstream_addr_group() const;
 
   int handle_downstream_push_promise(Downstream *downstream,
                                      int32_t promised_stream_id);

src/shrpx_http_downstream_connection.cc

@@ -565,7 +565,7 @@ int HttpDownstreamConnection::end_upload_data() {
 
 namespace {
 void remove_from_pool(HttpDownstreamConnection *dconn) {
-  auto group = dconn->get_downstream_addr_group();
+  auto &group = dconn->get_downstream_addr_group();
   auto &shared_addr = group->shared_addr;
 
   if (shared_addr->affinity == AFFINITY_NONE) {
@@ -677,6 +677,11 @@ int htp_hdrs_completecb(http_parser *htp) {
     resp.http_minor = 1;
   }
 
+  auto dconn = downstream->get_downstream_connection();
+
+  downstream->set_downstream_addr_group(dconn->get_downstream_addr_group());
+  downstream->set_addr(dconn->get_addr());
+
   if (resp.fs.parse_content_length() != 0) {
     downstream->set_response_state(Downstream::MSG_BAD_HEADER);
     return -1;
@@ -1192,9 +1197,9 @@ int HttpDownstreamConnection::actual_signal_write() {
 
 int HttpDownstreamConnection::noop() { return 0; }
 
-DownstreamAddrGroup *
+const std::shared_ptr<DownstreamAddrGroup> &
 HttpDownstreamConnection::get_downstream_addr_group() const {
-  return group_.get();
+  return group_;
 }
 
 DownstreamAddr *HttpDownstreamConnection::get_addr() const { return addr_; }

src/shrpx_http_downstream_connection.h

@@ -64,7 +64,8 @@ public:
 
   virtual bool poolable() const;
 
-  virtual DownstreamAddrGroup *get_downstream_addr_group() const;
+  virtual const std::shared_ptr<DownstreamAddrGroup> &
+  get_downstream_addr_group() const;
   virtual DownstreamAddr *get_addr() const;
 
   int read_clear();

src/shrpx_log.cc

@@ -45,6 +45,7 @@
 
 #include "shrpx_config.h"
 #include "shrpx_downstream.h"
+#include "shrpx_worker.h"
 #include "util.h"
 #include "template.h"
 
@@ -367,6 +368,21 @@ void upstream_accesslog(const std::vector<LogFragment> &lfv,
       std::tie(p, avail) =
           copy_l(lgsp.tls_info->session_reused ? "r" : ".", avail, p);
       break;
+    case SHRPX_LOGF_BACKEND_HOST:
+      if (!lgsp.downstream_addr) {
+        std::tie(p, avail) = copy_l("-", avail, p);
+        break;
+      }
+      std::tie(p, avail) = copy(lgsp.downstream_addr->host, avail, p);
+      break;
+    case SHRPX_LOGF_BACKEND_PORT:
+      if (!lgsp.downstream_addr) {
+        std::tie(p, avail) = copy_l("-", avail, p);
+        break;
+      }
+      std::tie(p, avail) =
+          copy(util::utos(lgsp.downstream_addr->port), avail, p);
+      break;
     case SHRPX_LOGF_NONE:
       break;
     default:

src/shrpx_log.h

@@ -85,6 +85,7 @@ using namespace nghttp2;
 namespace shrpx {
 
 class Downstream;
+struct DownstreamAddr;
 
 enum SeverityLevel { INFO, NOTICE, WARN, ERROR, FATAL };
 
@@ -131,6 +132,8 @@ enum LogFragmentType {
   SHRPX_LOGF_SSL_PROTOCOL,
   SHRPX_LOGF_SSL_SESSION_ID,
   SHRPX_LOGF_SSL_SESSION_REUSED,
+  SHRPX_LOGF_BACKEND_HOST,
+  SHRPX_LOGF_BACKEND_PORT,
 };
 
 struct LogFragment {
@@ -142,6 +145,7 @@ struct LogFragment {
 
 struct LogSpec {
   Downstream *downstream;
+  const DownstreamAddr *downstream_addr;
   StringRef remote_addr;
   StringRef method;
   StringRef path;