Merge pull request #13883 from ncteisen/channel-tracing

Channel Tracing Implementation; Part 1

19 files changed, 1087 insertions, 11 deletions

diff --git a/src/core/ext/filters/client_channel/client_channel.cc b/src/core/ext/filters/client_channel/client_channel.cc
index bbc5160bec..bf3911e5ee 100644
--- a/src/core/ext/filters/client_channel/client_channel.cc
+++ b/src/core/ext/filters/client_channel/client_channel.cc
@@ -38,12 +38,12 @@
 #include "src/core/ext/filters/client_channel/proxy_mapper_registry.h"
 #include "src/core/ext/filters/client_channel/resolver_registry.h"
 #include "src/core/ext/filters/client_channel/retry_throttle.h"
-#include "src/core/ext/filters/client_channel/status_util.h"
 #include "src/core/ext/filters/client_channel/subchannel.h"
 #include "src/core/ext/filters/deadline/deadline_filter.h"
 #include "src/core/lib/backoff/backoff.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/connected_channel.h"
+#include "src/core/lib/channel/status_util.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gprpp/inlined_vector.h"
 #include "src/core/lib/gprpp/manual_constructor.h"
diff --git a/src/core/ext/filters/client_channel/method_params.cc b/src/core/ext/filters/client_channel/method_params.cc
index 374b87e170..1f116bb67d 100644
--- a/src/core/ext/filters/client_channel/method_params.cc
+++ b/src/core/ext/filters/client_channel/method_params.cc
@@ -26,7 +26,7 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/ext/filters/client_channel/method_params.h"
-#include "src/core/ext/filters/client_channel/status_util.h"
+#include "src/core/lib/channel/status_util.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gprpp/memory.h"
 
diff --git a/src/core/ext/filters/client_channel/method_params.h b/src/core/ext/filters/client_channel/method_params.h
index 48ece29867..099924edf3 100644
--- a/src/core/ext/filters/client_channel/method_params.h
+++ b/src/core/ext/filters/client_channel/method_params.h
@@ -21,7 +21,7 @@
 
 #include <grpc/support/port_platform.h>
 
-#include "src/core/ext/filters/client_channel/status_util.h"
+#include "src/core/lib/channel/status_util.h"
 #include "src/core/lib/gprpp/ref_counted.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
 #include "src/core/lib/iomgr/exec_ctx.h"  // for grpc_millis
diff --git a/src/core/ext/filters/client_channel/subchannel.cc b/src/core/ext/filters/client_channel/subchannel.cc
index cae7cc35e3..d7815fb7e1 100644
--- a/src/core/ext/filters/client_channel/subchannel.cc
+++ b/src/core/ext/filters/client_channel/subchannel.cc
@@ -40,6 +40,7 @@
 #include "src/core/lib/debug/stats.h"
 #include "src/core/lib/gprpp/debug_location.h"
 #include "src/core/lib/gprpp/manual_constructor.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/profiling/timers.h"
diff --git a/src/core/lib/channel/channel_trace.cc b/src/core/lib/channel/channel_trace.cc
new file mode 100644
index 0000000000..67d5fd364b
--- /dev/null
+++ b/src/core/lib/channel/channel_trace.cc
@@ -0,0 +1,238 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <grpc/impl/codegen/port_platform.h>
+
+#include "src/core/lib/channel/channel_trace.h"
+
+#include <grpc/grpc.h>
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "src/core/lib/channel/channel_trace_registry.h"
+#include "src/core/lib/channel/status_util.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gpr/useful.h"
+#include "src/core/lib/gprpp/memory.h"
+#include "src/core/lib/iomgr/error.h"
+#include "src/core/lib/slice/slice_internal.h"
+#include "src/core/lib/surface/channel.h"
+#include "src/core/lib/transport/connectivity_state.h"
+#include "src/core/lib/transport/error_utils.h"
+
+namespace grpc_core {
+
+ChannelTrace::TraceEvent::TraceEvent(
+    Severity severity, grpc_slice data,
+    RefCountedPtr<ChannelTrace> referenced_tracer, ReferencedType type)
+    : severity_(severity),
+      data_(data),
+      timestamp_(grpc_millis_to_timespec(grpc_core::ExecCtx::Get()->Now(),
+                                         GPR_CLOCK_REALTIME)),
+      next_(nullptr),
+      referenced_tracer_(std::move(referenced_tracer)),
+      referenced_type_(type) {}
+
+ChannelTrace::TraceEvent::TraceEvent(Severity severity, grpc_slice data)
+    : severity_(severity),
+      data_(data),
+      timestamp_(grpc_millis_to_timespec(grpc_core::ExecCtx::Get()->Now(),
+                                         GPR_CLOCK_REALTIME)),
+      next_(nullptr) {}
+
+ChannelTrace::TraceEvent::~TraceEvent() { grpc_slice_unref_internal(data_); }
+
+ChannelTrace::ChannelTrace(size_t max_events)
+    : channel_uuid_(-1),
+      num_events_logged_(0),
+      list_size_(0),
+      max_list_size_(max_events),
+      head_trace_(nullptr),
+      tail_trace_(nullptr) {
+  if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
+  gpr_mu_init(&tracer_mu_);
+  channel_uuid_ = grpc_channel_trace_registry_register_channel_trace(this);
+  time_created_ = grpc_millis_to_timespec(grpc_core::ExecCtx::Get()->Now(),
+                                          GPR_CLOCK_REALTIME);
+}
+
+ChannelTrace::~ChannelTrace() {
+  if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
+  TraceEvent* it = head_trace_;
+  while (it != nullptr) {
+    TraceEvent* to_free = it;
+    it = it->next();
+    Delete<TraceEvent>(to_free);
+  }
+  grpc_channel_trace_registry_unregister_channel_trace(channel_uuid_);
+  gpr_mu_destroy(&tracer_mu_);
+}
+
+intptr_t ChannelTrace::GetUuid() const { return channel_uuid_; }
+
+void ChannelTrace::AddTraceEventHelper(TraceEvent* new_trace_event) {
+  ++num_events_logged_;
+  // first event case
+  if (head_trace_ == nullptr) {
+    head_trace_ = tail_trace_ = new_trace_event;
+  }
+  // regular event add case
+  else {
+    tail_trace_->set_next(new_trace_event);
+    tail_trace_ = tail_trace_->next();
+  }
+  ++list_size_;
+  // maybe garbage collect the end
+  if (list_size_ > max_list_size_) {
+    TraceEvent* to_free = head_trace_;
+    head_trace_ = head_trace_->next();
+    Delete<TraceEvent>(to_free);
+    --list_size_;
+  }
+}
+
+void ChannelTrace::AddTraceEvent(Severity severity, grpc_slice data) {
+  if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
+  AddTraceEventHelper(New<TraceEvent>(severity, data));
+}
+
+void ChannelTrace::AddTraceEventReferencingChannel(
+    Severity severity, grpc_slice data,
+    RefCountedPtr<ChannelTrace> referenced_tracer) {
+  if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
+  // create and fill up the new event
+  AddTraceEventHelper(
+      New<TraceEvent>(severity, data, std::move(referenced_tracer), Channel));
+}
+
+void ChannelTrace::AddTraceEventReferencingSubchannel(
+    Severity severity, grpc_slice data,
+    RefCountedPtr<ChannelTrace> referenced_tracer) {
+  if (max_list_size_ == 0) return;  // tracing is disabled if max_events == 0
+  // create and fill up the new event
+  AddTraceEventHelper(New<TraceEvent>(
+      severity, data, std::move(referenced_tracer), Subchannel));
+}
+
+namespace {
+
+// returns an allocated string that represents tm according to RFC-3339, and,
+// more specifically, follows:
+// https://developers.google.com/protocol-buffers/docs/proto3#json
+//
+// "Uses RFC 3339, where generated output will always be Z-normalized and uses
+// 0, 3, 6 or 9 fractional digits."
+char* fmt_time(gpr_timespec tm) {
+  char time_buffer[35];
+  char ns_buffer[11];  // '.' + 9 digits of precision
+  struct tm* tm_info = localtime((const time_t*)&tm.tv_sec);
+  strftime(time_buffer, sizeof(time_buffer), "%Y-%m-%dT%H:%M:%S", tm_info);
+  snprintf(ns_buffer, 11, ".%09d", tm.tv_nsec);
+  // This loop trims off trailing zeros by inserting a null character that the
+  // right point. We iterate in chunks of three because we want 0, 3, 6, or 9
+  // fractional digits.
+  for (int i = 7; i >= 1; i -= 3) {
+    if (ns_buffer[i] == '0' && ns_buffer[i + 1] == '0' &&
+        ns_buffer[i + 2] == '0') {
+      ns_buffer[i] = '\0';
+      // Edge case in which all fractional digits were 0.
+      if (i == 1) {
+        ns_buffer[0] = '\0';
+      }
+    } else {
+      break;
+    }
+  }
+  char* full_time_str;
+  gpr_asprintf(&full_time_str, "%s%sZ", time_buffer, ns_buffer);
+  return full_time_str;
+}
+
+const char* severity_string(ChannelTrace::Severity severity) {
+  switch (severity) {
+    case ChannelTrace::Severity::Info:
+      return "CT_INFO";
+    case ChannelTrace::Severity::Warning:
+      return "CT_WARNING";
+    case ChannelTrace::Severity::Error:
+      return "CT_ERROR";
+    default:
+      GPR_UNREACHABLE_CODE(return "CT_UNKNOWN");
+  }
+}
+
+}  // anonymous namespace
+
+void ChannelTrace::TraceEvent::RenderTraceEvent(grpc_json* json) const {
+  grpc_json* json_iterator = nullptr;
+  json_iterator = grpc_json_create_child(json_iterator, json, "description",
+                                         grpc_slice_to_c_string(data_),
+                                         GRPC_JSON_STRING, true);
+  json_iterator = grpc_json_create_child(json_iterator, json, "severity",
+                                         severity_string(severity_),
+                                         GRPC_JSON_STRING, false);
+  json_iterator =
+      grpc_json_create_child(json_iterator, json, "timestamp",
+                             fmt_time(timestamp_), GRPC_JSON_STRING, true);
+  if (referenced_tracer_ != nullptr) {
+    char* uuid_str;
+    gpr_asprintf(&uuid_str, "%" PRIdPTR, referenced_tracer_->channel_uuid_);
+    grpc_json* child_ref = grpc_json_create_child(
+        json_iterator, json,
+        (referenced_type_ == Channel) ? "channelRef" : "subchannelRef", nullptr,
+        GRPC_JSON_OBJECT, false);
+    json_iterator = grpc_json_create_child(
+        nullptr, child_ref,
+        (referenced_type_ == Channel) ? "channelId" : "subchannelId", uuid_str,
+        GRPC_JSON_STRING, true);
+    json_iterator = child_ref;
+  }
+}
+
+char* ChannelTrace::RenderTrace() const {
+  if (!max_list_size_)
+    return nullptr;  // tracing is disabled if max_events == 0
+  grpc_json* json = grpc_json_create(GRPC_JSON_OBJECT);
+  char* num_events_logged_str;
+  gpr_asprintf(&num_events_logged_str, "%" PRId64, num_events_logged_);
+  grpc_json* json_iterator = nullptr;
+  json_iterator =
+      grpc_json_create_child(json_iterator, json, "numEventsLogged",
+                             num_events_logged_str, GRPC_JSON_STRING, true);
+  json_iterator =
+      grpc_json_create_child(json_iterator, json, "creationTime",
+                             fmt_time(time_created_), GRPC_JSON_STRING, true);
+  grpc_json* events = grpc_json_create_child(json_iterator, json, "events",
+                                             nullptr, GRPC_JSON_ARRAY, false);
+  json_iterator = nullptr;
+  TraceEvent* it = head_trace_;
+  while (it != nullptr) {
+    json_iterator = grpc_json_create_child(json_iterator, events, nullptr,
+                                           nullptr, GRPC_JSON_OBJECT, false);
+    it->RenderTraceEvent(json_iterator);
+    it = it->next();
+  }
+  char* json_str = grpc_json_dump_to_string(json, 0);
+  grpc_json_destroy(json);
+  return json_str;
+}
+
+}  // namespace grpc_core
diff --git a/src/core/lib/channel/channel_trace.h b/src/core/lib/channel/channel_trace.h
new file mode 100644
index 0000000000..1df1e585f2
--- /dev/null
+++ b/src/core/lib/channel/channel_trace.h
@@ -0,0 +1,133 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_H
+#define GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_H
+
+#include <grpc/impl/codegen/port_platform.h>
+
+#include <grpc/grpc.h>
+#include "src/core/lib/gprpp/ref_counted.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/iomgr/error.h"
+#include "src/core/lib/json/json.h"
+
+namespace grpc_core {
+
+// Object used to hold live data for a channel. This data is exposed via the
+// channelz service:
+// https://github.com/grpc/proposal/blob/master/A14-channelz.md
+class ChannelTrace : public RefCounted<ChannelTrace> {
+ public:
+  ChannelTrace(size_t max_events);
+  ~ChannelTrace();
+
+  // returns the tracer's uuid
+  intptr_t GetUuid() const;
+
+  enum Severity {
+    Unset = 0,  // never to be used
+    Info,       // we start at 1 to avoid using proto default values
+    Warning,
+    Error
+  };
+
+  // Adds a new trace event to the tracing object
+  //
+  // TODO(ncteisen): as this call is used more and more throughout the gRPC
+  // stack, determine if it makes more sense to accept a char* instead of a
+  // slice.
+  void AddTraceEvent(Severity severity, grpc_slice data);
+
+  // Adds a new trace event to the tracing object. This trace event refers to a
+  // an event on a child of the channel. For example, if this channel has
+  // created a new subchannel, then it would record that with a TraceEvent
+  // referencing the new subchannel.
+  //
+  // TODO(ncteisen): Once channelz is implemented, the events should reference
+  // the overall channelz object, not just the ChannelTrace object.
+  // TODO(ncteisen): as this call is used more and more throughout the gRPC
+  // stack, determine if it makes more sense to accept a char* instead of a
+  // slice.
+  void AddTraceEventReferencingChannel(
+      Severity severity, grpc_slice data,
+      RefCountedPtr<ChannelTrace> referenced_tracer);
+  void AddTraceEventReferencingSubchannel(
+      Severity severity, grpc_slice data,
+      RefCountedPtr<ChannelTrace> referenced_tracer);
+
+  // Returns the tracing data rendered as a grpc json string.
+  // The string is owned by the caller and must be freed.
+  char* RenderTrace() const;
+
+ private:
+  // Types of objects that can be references by trace events.
+  enum ReferencedType { Channel, Subchannel };
+  // Private class to encapsulate all the data and bookkeeping needed for a
+  // a trace event.
+  class TraceEvent {
+   public:
+    // Constructor for a TraceEvent that references a different channel.
+    // TODO(ncteisen): once channelz is implemented, this should reference the
+    // overall channelz object, not just the ChannelTrace object
+    TraceEvent(Severity severity, grpc_slice data,
+               RefCountedPtr<ChannelTrace> referenced_tracer,
+               ReferencedType type);
+
+    // Constructor for a TraceEvent that does not reverence a different
+    // channel.
+    TraceEvent(Severity severity, grpc_slice data);
+
+    ~TraceEvent();
+
+    // Renders the data inside of this TraceEvent into a json object. This is
+    // used by the ChannelTrace, when it is rendering itself.
+    void RenderTraceEvent(grpc_json* json) const;
+
+    // set and get for the next_ pointer.
+    TraceEvent* next() const { return next_; }
+    void set_next(TraceEvent* next) { next_ = next; }
+
+   private:
+    Severity severity_;
+    grpc_slice data_;
+    gpr_timespec timestamp_;
+    TraceEvent* next_;
+    // the tracer object for the (sub)channel that this trace event refers to.
+    RefCountedPtr<ChannelTrace> referenced_tracer_;
+    // the type that the referenced tracer points to. Unused if this trace
+    // does not point to any channel or subchannel
+    ReferencedType referenced_type_;
+  };  // TraceEvent
+
+  // Internal helper to add and link in a trace event
+  void AddTraceEventHelper(TraceEvent* new_trace_event);
+
+  gpr_mu tracer_mu_;
+  intptr_t channel_uuid_;
+  uint64_t num_events_logged_;
+  size_t list_size_;
+  size_t max_list_size_;
+  TraceEvent* head_trace_;
+  TraceEvent* tail_trace_;
+  gpr_timespec time_created_;
+};
+
+}  // namespace grpc_core
+
+#endif /* GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_H */
diff --git a/src/core/lib/channel/channel_trace_registry.cc b/src/core/lib/channel/channel_trace_registry.cc
new file mode 100644
index 0000000000..6c82431467
--- /dev/null
+++ b/src/core/lib/channel/channel_trace_registry.cc
@@ -0,0 +1,80 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <grpc/impl/codegen/port_platform.h>
+
+#include "src/core/lib/avl/avl.h"
+#include "src/core/lib/channel/channel_trace.h"
+#include "src/core/lib/channel/channel_trace_registry.h"
+#include "src/core/lib/gpr/useful.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+
+// file global lock and avl.
+static gpr_mu g_mu;
+static grpc_avl g_avl;
+static gpr_atm g_uuid = 0;
+
+// avl vtable for uuid (intptr_t) -> ChannelTrace
+// this table is only looking, it does not own anything.
+static void destroy_intptr(void* not_used, void* user_data) {}
+static void* copy_intptr(void* key, void* user_data) { return key; }
+static long compare_intptr(void* key1, void* key2, void* user_data) {
+  return GPR_ICMP(key1, key2);
+}
+
+static void destroy_channel_trace(void* trace, void* user_data) {}
+static void* copy_channel_trace(void* trace, void* user_data) { return trace; }
+static const grpc_avl_vtable avl_vtable = {
+    destroy_intptr, copy_intptr, compare_intptr, destroy_channel_trace,
+    copy_channel_trace};
+
+void grpc_channel_trace_registry_init() {
+  gpr_mu_init(&g_mu);
+  g_avl = grpc_avl_create(&avl_vtable);
+}
+
+void grpc_channel_trace_registry_shutdown() {
+  grpc_avl_unref(g_avl, nullptr);
+  gpr_mu_destroy(&g_mu);
+}
+
+intptr_t grpc_channel_trace_registry_register_channel_trace(
+    grpc_core::ChannelTrace* channel_trace) {
+  intptr_t prior = gpr_atm_no_barrier_fetch_add(&g_uuid, 1);
+  gpr_mu_lock(&g_mu);
+  g_avl = grpc_avl_add(g_avl, (void*)prior, channel_trace, nullptr);
+  gpr_mu_unlock(&g_mu);
+  return prior;
+}
+
+void grpc_channel_trace_registry_unregister_channel_trace(intptr_t uuid) {
+  gpr_mu_lock(&g_mu);
+  g_avl = grpc_avl_remove(g_avl, (void*)uuid, nullptr);
+  gpr_mu_unlock(&g_mu);
+}
+
+grpc_core::ChannelTrace* grpc_channel_trace_registry_get_channel_trace(
+    intptr_t uuid) {
+  gpr_mu_lock(&g_mu);
+  grpc_core::ChannelTrace* ret = static_cast<grpc_core::ChannelTrace*>(
+      grpc_avl_get(g_avl, (void*)uuid, nullptr));
+  gpr_mu_unlock(&g_mu);
+  return ret;
+}
diff --git a/src/core/lib/channel/channel_trace_registry.h b/src/core/lib/channel/channel_trace_registry.h
new file mode 100644
index 0000000000..391ecba7de
--- /dev/null
+++ b/src/core/lib/channel/channel_trace_registry.h
@@ -0,0 +1,43 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_REGISTRY_H
+#define GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_REGISTRY_H
+
+#include <grpc/impl/codegen/port_platform.h>
+
+#include "src/core/lib/channel/channel_trace.h"
+
+#include <stdint.h>
+
+// TODO(ncteisen): convert this file to C++
+
+void grpc_channel_trace_registry_init();
+void grpc_channel_trace_registry_shutdown();
+
+// globally registers a ChannelTrace. Returns its unique uuid
+intptr_t grpc_channel_trace_registry_register_channel_trace(
+    grpc_core::ChannelTrace* channel_trace);
+// globally unregisters the ChannelTrace that is associated to uuid.
+void grpc_channel_trace_registry_unregister_channel_trace(intptr_t uuid);
+// if object with uuid has previously been registered, returns the ChannelTrace
+// associated with that uuid. Else returns nullptr.
+grpc_core::ChannelTrace* grpc_channel_trace_registry_get_channel_trace(
+    intptr_t uuid);
+
+#endif /* GRPC_CORE_LIB_CHANNEL_CHANNEL_TRACE_REGISTRY_H */
diff --git a/src/core/ext/filters/client_channel/status_util.cc b/src/core/lib/channel/status_util.cc
index 11f732ab44..563db40846 100644
--- a/src/core/ext/filters/client_channel/status_util.cc
+++ b/src/core/lib/channel/status_util.cc
@@ -18,7 +18,7 @@
 
 #include <grpc/support/port_platform.h>
 
-#include "src/core/ext/filters/client_channel/status_util.h"
+#include "src/core/lib/channel/status_util.h"
 
 #include "src/core/lib/gpr/useful.h"
 
diff --git a/src/core/ext/filters/client_channel/status_util.h b/src/core/lib/channel/status_util.h
index e018709730..5409de6b3c 100644
--- a/src/core/ext/filters/client_channel/status_util.h
+++ b/src/core/lib/channel/status_util.h
@@ -16,8 +16,8 @@
  *
  */
 
-#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_STATUS_UTIL_H
-#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_STATUS_UTIL_H
+#ifndef GRPC_CORE_LIB_CHANNEL_STATUS_UTIL_H
+#define GRPC_CORE_LIB_CHANNEL_STATUS_UTIL_H
 
 #include <grpc/support/port_platform.h>
 
@@ -55,4 +55,4 @@ class StatusCodeSet {
 }  // namespace internal
 }  // namespace grpc_core
 
-#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_STATUS_UTIL_H */
+#endif /* GRPC_CORE_LIB_CHANNEL_STATUS_UTIL_H */
diff --git a/src/core/lib/json/json.cc b/src/core/lib/json/json.cc
index 2141db4c5b..816241bbf0 100644
--- a/src/core/lib/json/json.cc
+++ b/src/core/lib/json/json.cc
@@ -21,6 +21,7 @@
 #include <string.h>
 
 #include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
 
 #include "src/core/lib/json/json.h"
 
@@ -46,5 +47,40 @@ void grpc_json_destroy(grpc_json* json) {
     json->parent->child = json->next;
   }
 
+  if (json->owns_value) {
+    gpr_free((void*)json->value);
+  }
+
   gpr_free(json);
 }
+
+grpc_json* grpc_json_link_child(grpc_json* parent, grpc_json* child,
+                                grpc_json* sibling) {
+  // first child case.
+  if (parent->child == nullptr) {
+    GPR_ASSERT(sibling == nullptr);
+    parent->child = child;
+    return child;
+  }
+  if (sibling == nullptr) {
+    sibling = parent->child;
+  }
+  // always find the right most sibling.
+  while (sibling->next != nullptr) {
+    sibling = sibling->next;
+  }
+  sibling->next = child;
+  return child;
+}
+
+grpc_json* grpc_json_create_child(grpc_json* sibling, grpc_json* parent,
+                                  const char* key, const char* value,
+                                  grpc_json_type type, bool owns_value) {
+  grpc_json* child = grpc_json_create(type);
+  grpc_json_link_child(parent, child, sibling);
+  child->owns_value = owns_value;
+  child->parent = parent;
+  child->value = value;
+  child->key = key;
+  return child;
+}
diff --git a/src/core/lib/json/json.h b/src/core/lib/json/json.h
index 3a62ef9cfb..f93b43048b 100644
--- a/src/core/lib/json/json.h
+++ b/src/core/lib/json/json.h
@@ -21,6 +21,7 @@
 
 #include <grpc/support/port_platform.h>
 
+#include <stdbool.h>
 #include <stdlib.h>
 
 #include "src/core/lib/json/json_common.h"
@@ -37,6 +38,9 @@ typedef struct grpc_json {
   grpc_json_type type;
   const char* key;
   const char* value;
+
+  /* if set, destructor will free value */
+  bool owns_value;
 } grpc_json;
 
 /* The next two functions are going to parse the input string, and
@@ -67,9 +71,24 @@ char* grpc_json_dump_to_string(grpc_json* json, int indent);
 
 /* Use these to create or delete a grpc_json object.
  * Deletion is recursive. We will not attempt to free any of the strings
- * in any of the objects of that tree.
+ * in any of the objects of that tree, unless the boolean, owns_value,
+ * is true.
  */
 grpc_json* grpc_json_create(grpc_json_type type);
 void grpc_json_destroy(grpc_json* json);
 
+/* Links the child json object into the parent's json tree. If the parent
+ * already has children, then passing in the most recently added child as the
+ * sibling parameter is an optimization. For if sibling is NULL, this function
+ * will manually traverse the tree in order to find the right most sibling.
+ */
+grpc_json* grpc_json_link_child(grpc_json* parent, grpc_json* child,
+                                grpc_json* sibling);
+
+/* Creates a child json object into the parent's json tree then links it in
+ * as described above. */
+grpc_json* grpc_json_create_child(grpc_json* sibling, grpc_json* parent,
+                                  const char* key, const char* value,
+                                  grpc_json_type type, bool owns_value);
+
 #endif /* GRPC_CORE_LIB_JSON_JSON_H */
diff --git a/src/core/lib/surface/channel.cc b/src/core/lib/surface/channel.cc
index 03353d6beb..cecc15b2df 100644
--- a/src/core/lib/surface/channel.cc
+++ b/src/core/lib/surface/channel.cc
@@ -21,6 +21,7 @@
 #include "src/core/lib/surface/channel.h"
 
 #include <inttypes.h>
+#include <limits.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -30,8 +31,12 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/channel/channel_trace.h"
 #include "src/core/lib/debug/stats.h"
 #include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gprpp/manual_constructor.h"
+#include "src/core/lib/gprpp/memory.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
 #include "src/core/lib/iomgr/iomgr.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/api_trace.h"
@@ -62,6 +67,8 @@ struct grpc_channel {
   gpr_mu registered_call_mu;
   registered_call* registered_calls;
 
+  grpc_core::RefCountedPtr<grpc_core::ChannelTrace> tracer;
+
   char* target;
 };
 
@@ -93,12 +100,14 @@ grpc_channel* grpc_channel_create_with_builder(
             grpc_error_string(error));
     GRPC_ERROR_UNREF(error);
     gpr_free(target);
-    goto done;
+    grpc_channel_args_destroy(args);
+    return channel;
   }
 
   memset(channel, 0, sizeof(*channel));
   channel->target = target;
   channel->is_client = grpc_channel_stack_type_is_client(channel_stack_type);
+  size_t channel_tracer_max_nodes = 0;  // default to off
   gpr_mu_init(&channel->registered_call_mu);
   channel->registered_calls = nullptr;
 
@@ -161,14 +170,33 @@ grpc_channel* grpc_channel_create_with_builder(
       channel->compression_options.enabled_algorithms_bitset =
           static_cast<uint32_t>(args->args[i].value.integer) |
           0x1; /* always support no compression */
+    } else if (0 == strcmp(args->args[i].key,
+                           GRPC_ARG_MAX_CHANNEL_TRACE_EVENTS_PER_NODE)) {
+      GPR_ASSERT(channel_tracer_max_nodes == 0);
+      // max_nodes defaults to 0 (which is off), clamped between 0 and INT_MAX
+      const grpc_integer_options options = {0, 0, INT_MAX};
+      channel_tracer_max_nodes =
+          (size_t)grpc_channel_arg_get_integer(&args->args[i], options);
     }
   }
 
-done:
   grpc_channel_args_destroy(args);
+  channel->tracer = grpc_core::MakeRefCounted<grpc_core::ChannelTrace>(
+      channel_tracer_max_nodes);
+  channel->tracer->AddTraceEvent(
+      grpc_core::ChannelTrace::Severity::Info,
+      grpc_slice_from_static_string("Channel created"));
   return channel;
 }
 
+char* grpc_channel_get_trace(grpc_channel* channel) {
+  return channel->tracer->RenderTrace();
+}
+
+intptr_t grpc_channel_get_uuid(grpc_channel* channel) {
+  return channel->tracer->GetUuid();
+}
+
 grpc_channel* grpc_channel_create(const char* target,
                                   const grpc_channel_args* input_args,
                                   grpc_channel_stack_type channel_stack_type,
@@ -377,6 +405,7 @@ static void destroy_channel(void* arg, grpc_error* error) {
     GRPC_MDELEM_UNREF(rc->authority);
     gpr_free(rc);
   }
+  channel->tracer.reset();
   GRPC_MDELEM_UNREF(channel->default_authority);
   gpr_mu_destroy(&channel->registered_call_mu);
   gpr_free(channel->target);
diff --git a/src/core/lib/surface/init.cc b/src/core/lib/surface/init.cc
index ac9f9e6066..bd436d6857 100644
--- a/src/core/lib/surface/init.cc
+++ b/src/core/lib/surface/init.cc
@@ -27,6 +27,7 @@
 #include <grpc/support/log.h>
 #include <grpc/support/time.h>
 #include "src/core/lib/channel/channel_stack.h"
+#include "src/core/lib/channel/channel_trace_registry.h"
 #include "src/core/lib/channel/connected_channel.h"
 #include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/debug/stats.h"
@@ -128,6 +129,7 @@ void grpc_init(void) {
     grpc_slice_intern_init();
     grpc_mdctx_global_init();
     grpc_channel_init_init();
+    grpc_channel_trace_registry_init();
     grpc_security_pre_init();
     grpc_core::ExecCtx::GlobalInit();
     grpc_iomgr_init();
@@ -176,6 +178,7 @@ void grpc_shutdown(void) {
       grpc_mdctx_global_shutdown();
       grpc_handshaker_factory_registry_shutdown();
       grpc_slice_intern_shutdown();
+      grpc_channel_trace_registry_shutdown();
       grpc_stats_shutdown();
     }
     grpc_core::ExecCtx::GlobalShutdown();
diff --git a/src/proto/grpc/channelz/BUILD b/src/proto/grpc/channelz/BUILD
new file mode 100644
index 0000000000..bdb03d5e2d
--- /dev/null
+++ b/src/proto/grpc/channelz/BUILD
@@ -0,0 +1,26 @@
+# Copyright 2018 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+licenses(["notice"])  # Apache v2
+
+load("//bazel:grpc_build_system.bzl", "grpc_proto_library", "grpc_package")
+
+grpc_package(name = "channelz", visibility = "public")
+
+grpc_proto_library(
+    name = "channelz_proto",
+    srcs = ["channelz.proto"],
+    has_services = True,
+    well_known_protos = True,
+)
diff --git a/src/proto/grpc/channelz/channelz.proto b/src/proto/grpc/channelz/channelz.proto
new file mode 100644
index 0000000000..14db66a654
--- /dev/null
+++ b/src/proto/grpc/channelz/channelz.proto
@@ -0,0 +1,456 @@
+// Copyright 2018 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package grpc.channelz;
+
+import "google/protobuf/any.proto";
+import "google/protobuf/duration.proto";
+import "google/protobuf/timestamp.proto";
+import "google/protobuf/wrappers.proto";
+
+// See go/grpc-channelz.
+
+// Channel is a logical grouping of channels, subchannels, and sockets.
+message Channel {
+  // The identifier for this channel.
+  ChannelRef ref = 1;
+  // Data specific to this channel.
+  ChannelData data = 2;
+  // At most one of 'channel_ref+subchannel_ref' and 'socket' is set.
+
+  // There are no ordering guarantees on the order of channel refs.
+  // There may not be cycles in the ref graph.
+  // A channel ref may be present in more than one channel or subchannel.
+  repeated ChannelRef channel_ref = 3;
+
+  // At most one of 'channel_ref+subchannel_ref' and 'socket' is set.
+  // There are no ordering guarantees on the order of subchannel refs.
+  // There may not be cycles in the ref graph.
+  // A sub channel ref may be present in more than one channel or subchannel.
+  repeated SubchannelRef subchannel_ref = 4;
+
+  // There are no ordering guarantees on the order of sockets.
+  repeated SocketRef socket = 5;
+}
+
+// Subchannel is a logical grouping of channels, subchannels, and sockets.
+// A subchannel is load balanced over by it's ancestor
+message Subchannel {
+  // The identifier for this channel.
+  SubchannelRef ref = 1;
+  // Data specific to this channel.
+  ChannelData data = 2;
+  // At most one of 'channel_ref+subchannel_ref' and 'socket' is set.
+
+  // There are no ordering guarantees on the order of channel refs.
+  // There may not be cycles in the ref graph.
+  // A channel ref may be present in more than one channel or subchannel.
+  repeated ChannelRef channel_ref = 3;
+
+  // At most one of 'channel_ref+subchannel_ref' and 'socket' is set.
+  // There are no ordering guarantees on the order of subchannel refs.
+  // There may not be cycles in the ref graph.
+  // A sub channel ref may be present in more than one channel or subchannel.
+  repeated SubchannelRef subchannel_ref = 4;
+
+  // There are no ordering guarantees on the order of sockets.
+  repeated SocketRef socket = 5;
+}
+
+// These come from the specified states in this document:
+// https://github.com/grpc/grpc/blob/master/doc/connectivity-semantics-and-api.md
+message ChannelConnectivityState {
+  enum State {
+    UNKNOWN = 0;
+    IDLE = 1;
+    CONNECTING = 2;
+    READY = 3;
+    TRANSIENT_FAILURE = 4;
+    SHUTDOWN = 5;
+  }
+  State state = 1;
+}
+
+message ChannelData {
+
+  ChannelConnectivityState state = 1;
+
+  // The target this channel originally tried to connect to.  May be absent
+  string target = 2;
+
+  ChannelTrace trace = 3;
+
+  // The number of calls started on the channel
+  int64 calls_started = 4;
+  // The number of calls that have completed with an OK status
+  int64 calls_succeeded = 5;
+  // The number of calls that have a completed with a non-OK status
+  int64 calls_failed = 6;
+
+  // The last time a call was started on the channel.
+  google.protobuf.Timestamp last_call_started_timestamp = 7;
+}
+
+// A trace event is an interesting thing that happened to a channel or
+// subchannel, such as creation, address resolution, subchannel creation, etc.
+message ChannelTraceEvent {
+  // High level description of the event.
+  string description = 1;
+  // The supported severity levels of trace events.
+  enum Severity {
+    CT_UNKNOWN = 0;
+    CT_INFO = 1;
+    CT_WARNING = 2;
+    CT_ERROR = 3;
+  }
+  // the severity of the trace event
+  Severity severity = 2;
+  // When this event occurred.
+  google.protobuf.Timestamp timestamp = 3;
+  // ref of referenced channel or subchannel.
+  // Optional, only present if this event refers to a child object. For example,
+  // this field would be filled if this trace event was for a subchannel being
+  // created.
+  oneof child_ref {
+    ChannelRef channel_ref = 4;
+    SubchannelRef subchannel_ref = 5;
+  }
+}
+
+message ChannelTrace {
+  // Number of events ever logged in this tracing object. This can differ from
+  // events.size() because events can be overwritten or garbage collected by
+  // implementations.
+  int64 num_events_logged = 1;
+  // Time that this channel was created.
+  google.protobuf.Timestamp creation_time = 2;
+  // List of events that have occurred on this channel.
+  repeated ChannelTraceEvent events = 3;
+}
+
+message ChannelRef {
+  // The globally unique id for this channel.  Must be a positive number.
+  int64 channel_id = 1;
+  // An optional name associated with the channel.
+  string name = 2;
+  // Intentionally don't use field numbers from other refs.
+  reserved 3, 4, 5, 6;
+}
+
+message SubchannelRef {
+  // The globally unique id for this subchannel.  Must be a positive number.
+  int64 subchannel_id = 7;
+  // An optional name associated with the subchannel.
+  string name = 8;
+  // Intentionally don't use field numbers from other refs.
+  reserved 1, 2, 3, 4, 5, 6;
+}
+
+message SocketRef {
+  int64 socket_id = 3;
+  // An optional name associated with the socket.
+  string name = 4;
+  // Intentionally don't use field numbers from other refs.
+  reserved 1, 2, 5, 6, 7, 8;
+}
+
+message ServerRef {
+  // A globally unique identifier for this server.   Must be a positive number.
+  int64 server_id = 5;
+  // An optional name associated with the server.
+  string name = 6;
+  // Intentionally don't use field numbers from other refs.
+  reserved 1, 2, 3, 4, 7, 8;
+}
+
+message Server {
+  ServerRef ref = 1;
+  ServerData data = 2;
+
+  // The sockets that the server is listening on.  There are no ordering
+  // guarantees.
+  repeated SocketRef listen_socket = 3;
+}
+
+message ServerData {
+  ChannelTrace trace = 1;
+
+  // The number of incoming calls started on the server
+  int64 calls_started = 2;
+  // The number of incoming calls that have completed with an OK status
+  int64 calls_succeeded = 3;
+  // The number of incoming calls that have a completed with a non-OK status
+  int64 calls_failed = 4;
+
+  // The last time a call was started on the server.
+  google.protobuf.Timestamp last_call_started_timestamp = 5;
+}
+
+// Information about an actual connection.  Pronounced "sock-ay".
+message Socket {
+  SocketRef ref = 1;
+
+  SocketData data = 2;
+  // The locally bound address.
+  Address local = 3;
+  // The remote bound address.  May be absent.
+  Address remote = 4;
+  Security security = 5;
+
+  // Optional, represents the name of the remote endpoint, if different than
+  // the original target name.
+  string remote_name = 6;
+}
+
+message SocketData {
+  // The number of streams that have been started.
+  int64 streams_started = 1;
+  // The number of streams that have ended successfully with the EoS bit set for
+  //  both end points
+  int64 streams_succeeded = 2;
+  // The number of incoming streams that have a completed with a non-OK status
+  int64 streams_failed = 3;
+
+  // The number of messages successfully sent on this socket.
+  int64 messages_sent = 4;
+  int64 messages_received = 5;
+
+  // The number of keep alives sent.  This is typically implemented with HTTP/2
+  // ping messages.
+  int64 keep_alives_sent = 6;
+
+  // The last time a stream was created by this endpoint.  Usually unset for
+  // servers.
+  google.protobuf.Timestamp last_local_stream_created_timestamp = 7;
+  // The last time a stream was created by the remote endpoint.  Usually unset
+  // for clients.
+  google.protobuf.Timestamp last_remote_stream_created_timestamp = 8;
+
+  // The last time a message was sent by this endpoint.
+  google.protobuf.Timestamp last_message_sent_timestamp = 9;
+  // The last time a message was received by this endpoint.
+  google.protobuf.Timestamp last_message_received_timestamp = 10;
+
+  // The amount of window, granted to the local endpoint by the remote endpoint.
+  // This may be slightly out of date due to network latency.  This does NOT
+  // include stream level or TCP level flow control info.
+  google.protobuf.Int64Value local_flow_control_window = 11;
+
+  // The amount of window, granted to the remote endpoint by the local endpoint.
+  // This may be slightly out of date due to network latency.  This does NOT
+  // include stream level or TCP level flow control info.
+  google.protobuf.Int64Value  remote_flow_control_window = 12;
+
+  repeated SocketOption option = 13;
+}
+
+message Address {
+  message TcpIpAddress {
+    // Either the IPv4 or IPv6 address in bytes.  Will either be 4 bytes or 16
+    // bytes in length.
+    bytes ip_address = 1;
+    // 0-64k, or -1 if not appropriate.
+    int32 port = 2;
+  }
+  // A Unix Domain Socket address.
+  message UdsAddress {
+    string filename = 1;
+  }
+  // An address type not included above.
+  message OtherAddress {
+    // The human readable version of the value.
+    string name = 1;
+    // The actual address message.
+    google.protobuf.Any value = 2;
+  }
+
+  oneof address {
+    TcpIpAddress tcpip_address = 1;
+    UdsAddress uds_address = 2;
+    OtherAddress other_address = 3;
+  }
+}
+
+message Security {
+  message Tls {
+    // The key exchange used.  e.g. X25519
+    string key_exchange = 1;
+    // The cipher used. e.g. AES_128_GCM.
+    string cipher = 2;
+    // the certificate used by this endpoint.
+    bytes local_certificate = 3;
+    // the certificate used by the remote endpoint.
+    bytes remote_certificate = 4;
+  }
+  message OtherSecurity {
+    // The human readable version of the value.
+    string name = 1;
+    // The actual security details message.
+    google.protobuf.Any value = 2;
+  }
+  oneof model {
+    Tls tls = 1;
+    OtherSecurity other = 2;
+  }
+}
+
+message SocketOption {
+  string name = 1;
+  // The human readable value of this socket option.  At least one of value or
+  // additional will be set.
+  string value = 2;
+  // Additional data associated with the socket option.  At least one of value
+  // or additional will be set.
+  google.protobuf.Any additional = 3;
+}
+
+// For use with SocketOption's additional field.  This is primarily used for
+// SO_RCVTIMEO and SO_SNDTIMEO
+message SocketOptionTimeout {
+  google.protobuf.Duration duration = 1;
+}
+
+message SocketOptionLinger {
+  bool active = 1;
+  google.protobuf.Duration duration = 2;
+}
+
+// Tcp info for SOL_TCP, TCP_INFO
+message SocketOptionTcpInfo {
+  uint32 tcpi_state = 1;
+
+  uint32 tcpi_ca_state = 2;
+  uint32 tcpi_retransmits = 3;
+  uint32 tcpi_probes = 4;
+  uint32 tcpi_backoff = 5;
+  uint32 tcpi_options = 6;
+  uint32 tcpi_snd_wscale = 7;
+  uint32 tcpi_rcv_wscale = 8;
+
+  uint32 tcpi_rto = 9;
+  uint32 tcpi_ato = 10;
+  uint32 tcpi_snd_mss = 11;
+  uint32 tcpi_rcv_mss = 12;
+
+  uint32 tcpi_unacked = 13;
+  uint32 tcpi_sacked = 14;
+  uint32 tcpi_lost = 15;
+  uint32 tcpi_retrans = 16;
+  uint32 tcpi_fackets = 17;
+
+  uint32 tcpi_last_data_sent = 18;
+  uint32 tcpi_last_ack_sent = 19;
+  uint32 tcpi_last_data_recv = 20;
+  uint32 tcpi_last_ack_recv = 21;
+
+  uint32 tcpi_pmtu = 22;
+  uint32 tcpi_rcv_ssthresh = 23;
+  uint32 tcpi_rtt = 24;
+  uint32 tcpi_rttvar = 25;
+  uint32 tcpi_snd_ssthresh = 26;
+  uint32 tcpi_snd_cwnd = 27;
+  uint32 tcpi_advmss = 28;
+  uint32 tcpi_reordering = 29;
+}
+
+service Channelz {
+  // Gets all root channels (e.g. channels the application has directly
+  // created). This does not include subchannels nor non-top level channels.
+  rpc GetTopChannels(GetTopChannelsRequest) returns (GetTopChannelsResponse);
+  // Gets all servers that exist in the process.
+  rpc GetServers(GetServersRequest) returns (GetServersResponse);
+  // Gets all server sockets that exist in the process.
+  rpc GetServerSockets(GetServerSocketsRequest) returns (GetServerSocketsResponse);
+  // Returns a single Channel, or else a NOT_FOUND code.
+  rpc GetChannel(GetChannelRequest) returns (GetChannelResponse);
+  // Returns a single Subchannel, or else a NOT_FOUND code.
+  rpc GetSubchannel(GetSubchannelRequest) returns (GetSubchannelResponse);
+  // Returns a single Socket or else a NOT_FOUND code.
+  rpc GetSocket(GetSocketRequest) returns (GetSocketResponse);
+}
+
+message GetServersRequest {
+  // start_server_id indicates that only servers at or above this id should be
+  // included in the results.
+  int64 start_server_id = 1;
+}
+
+message GetServersResponse {
+  // list of servers that the connection detail service knows about.  Sorted in
+  // ascending server_id order.
+  repeated Server server = 1;
+  // If set, indicates that the list of servers is the final list.  Requesting
+  // more servers will only return more if they are created after this RPC
+  // completes.
+  bool end = 2;
+}
+
+message GetServerSocketsRequest {
+  int64 server_id = 1;
+  // start_socket_id indicates that only sockets at or above this id should be
+  // included in the results.
+  int64 start_socket_id = 2;
+}
+
+message GetServerSocketsResponse {
+  // list of socket refs that the connection detail service knows about.  Sorted in
+  // ascending socket_id order.
+  repeated SocketRef socket_ref = 1;
+  // If set, indicates that the list of sockets is the final list.  Requesting
+  // more sockets will only return more if they are created after this RPC
+  // completes.
+  bool end = 2;
+}
+
+message GetTopChannelsRequest {
+  // start_channel_id indicates that only channels at or above this id should be
+  // included in the results.
+  int64 start_channel_id = 1;
+}
+
+message GetTopChannelsResponse {
+  // list of channels that the connection detail service knows about.  Sorted in
+  // ascending channel_id order.
+  repeated Channel channel = 1;
+  // If set, indicates that the list of channels is the final list.  Requesting
+  // more channels can only return more if they are created after this RPC
+  // completes.
+  bool end = 2;
+}
+
+message GetChannelRequest {
+  int64 channel_id = 1;
+}
+
+message GetChannelResponse {
+  Channel channel = 1;
+}
+
+message GetSubchannelRequest {
+  int64 subchannel_id = 1;
+}
+
+message GetSubchannelResponse {
+  Subchannel subchannel = 1;
+}
+
+message GetSocketRequest {
+  int64 socket_id = 1;
+}
+
+message GetSocketResponse {
+  Socket socket = 1;
+}
diff --git a/src/python/grpcio/grpc_core_dependencies.py b/src/python/grpcio/grpc_core_dependencies.py
index d96cbec292..9807300527 100644
--- a/src/python/grpcio/grpc_core_dependencies.py
+++ b/src/python/grpcio/grpc_core_dependencies.py
@@ -60,10 +60,13 @@ CORE_SOURCE_FILES = [
     'src/core/lib/channel/channel_args.cc',
     'src/core/lib/channel/channel_stack.cc',
     'src/core/lib/channel/channel_stack_builder.cc',
+    'src/core/lib/channel/channel_trace.cc',
+    'src/core/lib/channel/channel_trace_registry.cc',
     'src/core/lib/channel/connected_channel.cc',
     'src/core/lib/channel/handshaker.cc',
     'src/core/lib/channel/handshaker_factory.cc',
     'src/core/lib/channel/handshaker_registry.cc',
+    'src/core/lib/channel/status_util.cc',
     'src/core/lib/compression/compression.cc',
     'src/core/lib/compression/compression_internal.cc',
     'src/core/lib/compression/message_compress.cc',
@@ -312,7 +315,6 @@ CORE_SOURCE_FILES = [
     'src/core/ext/filters/client_channel/resolver.cc',
     'src/core/ext/filters/client_channel/resolver_registry.cc',
     'src/core/ext/filters/client_channel/retry_throttle.cc',
-    'src/core/ext/filters/client_channel/status_util.cc',
     'src/core/ext/filters/client_channel/subchannel.cc',
     'src/core/ext/filters/client_channel/subchannel_index.cc',
     'src/core/ext/filters/client_channel/uri_parser.cc',
diff --git a/src/ruby/ext/grpc/rb_grpc_imports.generated.c b/src/ruby/ext/grpc/rb_grpc_imports.generated.c
index c045480ff4..1c042739a8 100644
--- a/src/ruby/ext/grpc/rb_grpc_imports.generated.c
+++ b/src/ruby/ext/grpc/rb_grpc_imports.generated.c
@@ -68,6 +68,8 @@ grpc_channel_get_info_type grpc_channel_get_info_import;
 grpc_insecure_channel_create_type grpc_insecure_channel_create_import;
 grpc_lame_client_channel_create_type grpc_lame_client_channel_create_import;
 grpc_channel_destroy_type grpc_channel_destroy_import;
+grpc_channel_get_trace_type grpc_channel_get_trace_import;
+grpc_channel_get_uuid_type grpc_channel_get_uuid_import;
 grpc_call_cancel_type grpc_call_cancel_import;
 grpc_call_cancel_with_status_type grpc_call_cancel_with_status_import;
 grpc_call_ref_type grpc_call_ref_import;
@@ -304,6 +306,8 @@ void grpc_rb_load_imports(HMODULE library) {
   grpc_insecure_channel_create_import = (grpc_insecure_channel_create_type) GetProcAddress(library, "grpc_insecure_channel_create");
   grpc_lame_client_channel_create_import = (grpc_lame_client_channel_create_type) GetProcAddress(library, "grpc_lame_client_channel_create");
   grpc_channel_destroy_import = (grpc_channel_destroy_type) GetProcAddress(library, "grpc_channel_destroy");
+  grpc_channel_get_trace_import = (grpc_channel_get_trace_type) GetProcAddress(library, "grpc_channel_get_trace");
+  grpc_channel_get_uuid_import = (grpc_channel_get_uuid_type) GetProcAddress(library, "grpc_channel_get_uuid");
   grpc_call_cancel_import = (grpc_call_cancel_type) GetProcAddress(library, "grpc_call_cancel");
   grpc_call_cancel_with_status_import = (grpc_call_cancel_with_status_type) GetProcAddress(library, "grpc_call_cancel_with_status");
   grpc_call_ref_import = (grpc_call_ref_type) GetProcAddress(library, "grpc_call_ref");
diff --git a/src/ruby/ext/grpc/rb_grpc_imports.generated.h b/src/ruby/ext/grpc/rb_grpc_imports.generated.h
index 4f07452c68..9a09321364 100644
--- a/src/ruby/ext/grpc/rb_grpc_imports.generated.h
+++ b/src/ruby/ext/grpc/rb_grpc_imports.generated.h
@@ -179,6 +179,12 @@ extern grpc_lame_client_channel_create_type grpc_lame_client_channel_create_impo
 typedef void(*grpc_channel_destroy_type)(grpc_channel* channel);
 extern grpc_channel_destroy_type grpc_channel_destroy_import;
 #define grpc_channel_destroy grpc_channel_destroy_import
+typedef char*(*grpc_channel_get_trace_type)(grpc_channel* channel);
+extern grpc_channel_get_trace_type grpc_channel_get_trace_import;
+#define grpc_channel_get_trace grpc_channel_get_trace_import
+typedef intptr_t(*grpc_channel_get_uuid_type)(grpc_channel* channel);
+extern grpc_channel_get_uuid_type grpc_channel_get_uuid_import;
+#define grpc_channel_get_uuid grpc_channel_get_uuid_import
 typedef grpc_call_error(*grpc_call_cancel_type)(grpc_call* call, void* reserved);
 extern grpc_call_cancel_type grpc_call_cancel_import;
 #define grpc_call_cancel grpc_call_cancel_import