grpcdebug

grpcdebug is a command line interface focusing on simplifying the debugging process of gRPC applications. grpcdebug fetches the internal states of the gRPC library from the application via gRPC protocol and provide a human-friendly UX to browse them. Currently, it supports Channelz/Health Checking/CSDS (aka. admin services). In other words, it can fetch statistics about how many RPCs has being sent or failed on a given gRPC channel, it can inspect address resolution results, it can dump the in-effective xDS configuration that directs the routing of RPCs.

If you are looking for a tool to send gRPC requests and interact with a gRPC server, please checkout https://github.com/fullstorydev/grpcurl.

grpcdebug is an gRPC service admin CLI

Usage:
  grpcdebug <target address> [flags] <command>

Available Commands:
  channelz    Display gRPC states in a human readable way.
  health      Check health status of the target service (default "").
  help        Help about any command
  xds         Fetch xDS related information.

Flags:
      --credential_file string        Sets the path of the credential file; used in [tls] mode
  -h, --help                          help for grpcdebug
      --security string               Defines the type of credentials to use [tls, google-default, insecure] (default "insecure")
      --server_name_override string   Overrides the peer server name if non empty; used in [tls] mode
  -t, --timestamp                     Print timestamp as RFC3339 instead of human readable strings
  -v, --verbose                       Print verbose information for debugging

Use "grpcdebug <target address>  [command] --help" for more information about a command.

grpcdebug

Installation

Use Compiled Binaries

The download links of the binaries can be found at https://github.com/grpc-ecosystem/grpcdebug/releases. You can find the precompiled artifacts for macOS/Linux/Windows.

Compile From Source

Minimum Golang Version 1.15. Official Golang install guide: https://golang.org/doc/install.

You can install the grpcdebug tool using command:

# For Golang 1.16+
go install -v github.com/grpc-ecosystem/grpcdebug@latest
# For Golang 1.15
GO111MODULE=on go get -v github.com/grpc-ecosystem/grpcdebug

You can check your Golang version with:

go version

Don't forget to add Golang binaries to your PATH:

export PATH=$PATH:$(go env GOPATH)/bin

Quick Start

If certain commands are confusing, please try to use -h to get more context. Suggestions and ideas are welcome, please post them to https://github.com/grpc-ecosystem/grpcdebug/issues!

If you haven't got your gRPC application instrumented, feel free to try out the mocking testserver which implemented admin services.

cd internal/testing/testserver
go run main.go
# Serving Business Logic on :10001
# Serving Insecure Admin Services on :50051
# Serving Secure Admin Services on :50052
# ...

Connect & Security

Insecure Connection

To connect to a gRPC endpoint without any credentials, we don't use any special flags. If the local network can connect to the given gRPC endpoint, it should just work. For example, if I have a gRPC application exposing admin services at localhost:50051:

grpcdebug localhost:50051 channelz channels

TLS Connection - Flags

One way to establish a TLS connection with grpcdebug is by specifying the credentials via command line flags. For example:

grpcdebug localhost:50052 --security=tls --credential_file=./internal/testing/ca.pem --server_name_override="*.test.youtube.com" channelz channels

Server Connection Config

Alternatively, like OpenSSH clients, you can specify the security settings in a grpcdebug_config.yaml file. grpcdebug CLI will find matching connection config and then use it to connect.

servers:
  "pattern string":
    real_address: string
    security: insecure/tls
    credential_file: string
    server_name_override: string

Here is an example config file grpcdebug_config.yaml.

Each server config can have the following settings:

Pattern: the string right after Server which dictates if this rule should apply;
RealAddress: if present, override the given target address, which allows giving nicknames/aliases to frequently used addresses;
Security: allows insecure or tls, expecting more in the future;
CredentialFile: path to the credential file;
ServerNameOverride: override the hostname, which is useful for local reproductions to comply with the certificates' common name requirement.

grpcdebug searches the config file in the following order:

Check if the environment variable GRPCDEBUG_CONFIG is set, if so, load from the given path;
Try to load the grpcdebug_config.yaml file in the current working directory;
Try to load the grpcdebug_config.yaml file in the user config directory (Linux: $HOME/.config, macOS: $HOME/Library/Application Support, Windows: %AppData%, see os.UserConfigDir()).

For example, we can connect to our mock test server's secure admin port via:

GRPCDEBUG_CONFIG=internal/testing/grpcdebug_config.yaml grpcdebug localhost:50052 channelz channels
# Or
GRPCDEBUG_CONFIG=internal/testing/grpcdebug_config.yaml grpcdebug prod channelz channels

Health

grpcdebug can be used to fetch the health checking status of a peer gRPC application (see health.proto). gRPC's health checking works at the service-level, meaning services registered on the same gRPC server may have different health statuses. The health status of service "" is used to represent the overall health status of the gRPC application.

To simply fetch the overall health status:

grpcdebug localhost:50051 health
# <Overall>:  SERVING
# or
# <Overall>:  NOT_SERVING

Or fetch individual service's health status:

grpcdebug localhost:50051 health helloworld.Greeter
# <Overall>:            SERVING
# helloworld.Greeter:   SERVING

Channelz

Channelz is a channel tracing library that allows applications to remotely query gRPC internal debug information. Also, Channelz has a web interface (see gdebug). grpcdebug is able to fetch information and present it in a more readable way.

Generally, you wil start with either the servers or channels command and then work down to the details.

Usage 1: Raw Channelz Output

For all Channelz commands, you can add --json to get the raw Channelz output.

grpcdebug localhost:50051 channelz servers --json
#[
#  {
#    "ref": {
#      "server_id": 2,
#      "name": "ServerImpl{logId=2, transportServer=NettyServer{logId=1, addresses=[0.0.0.0/0.0.0.0:50051]}}"
#    },
#    "data": {
#      "calls_started": 3,
#      "calls_succeeded": 2,
#      "last_call_started_timestamp": {
#        "seconds": 1680220688,
#        "nanos": 444000000
#      }
#    },
#    "listen_socket": [
#      {
#        "socket_id": 3,
#        "name": "ListenSocket{logId=3, channel=[id: 0x05f9f16c, L:/0:0:0:0:0:0:0:0%0:50051]}"
#      }
#    ]
#  }
#]

Usage 2: List Client Channels

grpcdebug localhost:50051 channelz channels
# Channel ID   Target            State     Calls(Started/Succeeded/Failed)   Created Time
# 7            localhost:10001   READY     5136/4631/505                     8 minutes ago

Usage 3: List Servers

grpcdebug localhost:50051 channelz servers
# Server ID   Listen Addresses   Calls(Started/Succeeded/Failed)   Last Call Started
# 1           [:::10001]         2852/2530/322                     now
# 2           [:::50051]         29/28/0                           now
# 3           [:::50052]         4/4/0                             26 seconds ago

Usage 4: Inspect a Channel

You can identify a channel via the Channel ID.

grpcdebug localhost:50051 channelz channel 7
# Channel ID:        7
# Target:            localhost:10001
# State:             READY
# Calls Started:     3976
# Calls Succeeded:   3520
# Calls Failed:      456
# Created Time:      6 minutes ago
# ---
# Subchannel ID   Target            State     Calls(Started/Succeeded/Failed)   CreatedTime
# 8               localhost:10001   READY     3976/3520/456                     6 minutes ago
# ---
# Severity   Time            Child Ref                      Description
# CT_INFO    6 minutes ago                                  Channel Created
# CT_INFO    6 minutes ago                                  Resolver state updated: {Addresses:[{Addr:localhost:10001 ServerName: Attributes:<nil> Type:0 Metadata:<nil>}] ServiceConfig:<nil> Attributes:<nil>} (resolver returned new addresses)
# CT_INFO    6 minutes ago                                  Channel switches to new LB policy "pick_first"
# CT_INFO    6 minutes ago   subchannel(subchannel_id:8 )   Subchannel(id:8) created
# CT_INFO    6 minutes ago                                  Channel Connectivity change to CONNECTING
# CT_INFO    6 minutes ago                                  Channel Connectivity change to READY

Usage 5: Inspect a Subchannel

grpcdebug localhost:50051 channelz subchannel 8
# Subchannel ID:     8
# Target:            localhost:10001
# State:             READY
# Calls Started:     4490
# Calls Succeeded:   3966
# Calls Failed:      524
# Created Time:      7 minutes ago
# ---
# Socket ID   Local->Remote          Streams(Started/Succeeded/Failed)   Messages(Sent/Received)
# 9           ::1:47436->::1:10001   4490/4490/0                         4490/3966

Usage 6: Inspect a Socket

grpcdebug localhost:50051 channelz socket 9
# Socket ID:                       9
# Address:                         ::1:47436->::1:10001
# Streams Started:                 4807
# Streams Succeeded:               4807
# Streams Failed:                  0
# Messages Sent:                   4807
# Messages Received:               4243
# Keep Alives Sent:                0
# Last Local Stream Created:       now
# Last Remote Stream Created:      a long while ago
# Last Message Sent Created:       now
# Last Message Received Created:   now
# Local Flow Control Window:       65535
# Remote Flow Control Window:      65535
# ---
# Socket Options Name   Value
# SO_LINGER             [type.googleapis.com/grpc.channelz.v1.SocketOptionLinger]:{duration:{}}
# SO_RCVTIMEO           [type.googleapis.com/grpc.channelz.v1.SocketOptionTimeout]:{duration:{}}
# SO_SNDTIMEO           [type.googleapis.com/grpc.channelz.v1.SocketOptionTimeout]:{duration:{}}
# TCP_INFO              [type.googleapis.com/grpc.channelz.v1.SocketOptionTcpInfo]:{tcpi_state:1  tcpi_options:7  tcpi_rto:204000  tcpi_ato:40000  tcpi_snd_mss:32768  tcpi_rcv_mss:1093  tcpi_last_data_sent:16  tcpi_last_data_recv:16  tcpi_last_ack_recv:16  tcpi_pmtu:65536  tcpi_rcv_ssthresh:65476  tcpi_rtt:192  tcpi_rttvar:153  tcpi_snd_ssthresh:2147483647  tcpi_snd_cwnd:10  tcpi_advmss:65464  tcpi_reordering:3}
# ---
# Security Model:   TLS
# Standard Name:    TLS_AES_128_GCM_SHA256

Usage 7: Inspect a Server

grpcdebug localhost:50051 channelz server 1
# Server Id:           1
# Listen Addresses:    [:::10001]
# Calls Started:       5250
# Calls Succeeded:     4647
# Calls Failed:        603
# Last Call Started:   now
# ---
# Socket ID   Local->Remote          Streams(Started/Succeeded/Failed)   Messages(Sent/Received)
# 10          ::1:10001->::1:47436   5250/5250/0                         4647/5250

Usage 8: Pagination

In production, there may be thousands of clients/servers/sockets. It would be very noisy to print all of them at once, so Channelz supports pagination through start_id and max_results

grpcdebug localhost:50051 channelz servers --start_id=0 --max_results=1
# Server ID   Listen Addresses   Calls(Started/Succeeded/Failed)   Last Call Started
# 1           [:::10001]         2852/2530/322                     now
grpcdebug localhost:50051 channelz servers --start_id=2 --max_results=2
# Server ID   Listen Addresses   Calls(Started/Succeeded/Failed)   Last Call Started
# 2           [:::50051]         29/28/0                           now
# 3           [:::50052]         4/4/0                             26 seconds ago

It works similarly for printing channels via channelz channels and printing server sockets via channelz server.

Debug xDS

xDS is a data plane configuration API commonly used in service mesh projects. It's created by Envoy, used by Istio, Traffic Director, and gRPC.

Usage 1: xDS Resources Overview

The xDS resources status might be REQUESTED/DOES_NOT_EXIST/ACKED/NACKED (see config_dump.proto). This view is intended for a quick scan if a configuration is propagated from the service mesh control plane.

grpcdebug localhost:50051 xds status
# Name                                                                   Status    Version               Type                                                                 LastUpdated
# xds-test-server:1337                                                   ACKED     1617141154495058478   type.googleapis.com/envoy.config.listener.v3.Listener                2 days ago
# URL_MAP/1040920224690_sergii-psm-test-url-map_0_xds-test-server:1337   ACKED     1617141154495058478   type.googleapis.com/envoy.config.route.v3.RouteConfiguration         2 days ago
# cloud-internal-istio:cloud_mp_1040920224690_6530603179561593229        ACKED     1617141154495058478   type.googleapis.com/envoy.config.cluster.v3.Cluster                  2 days ago
# cloud-internal-istio:cloud_mp_1040920224690_6530603179561593229        ACKED     1                     type.googleapis.com/envoy.config.endpoint.v3.ClusterLoadAssignment   2 days ago

Usage 2: Dump xDS Configs

grpcdebug localhost:50051 xds config
# {
#   "config":  [
#     {
#       "node":  {
#         "id":  "projects/1040920224690/networks/default/nodes/5cc9170c-d5b4-4061-b431-c1d43e6ac0ab",
#         "cluster":  "cluster",
#         "metadata":  {
#           "INSTANCE_IP":  "192.168.120.31",
#           "TRAFFICDIRECTOR_GCP_PROJECT_NUMBER":  "1040920224690",
#           "TRAFFICDIRECTOR_NETWORK_NAME":  "default"
#         },
# ...

For an example config dump, see csds_config_dump.json.

Usage 3: Filter xDS Configs

The dumped xDS config can be quite verbose, if I only interested in certain xDS type, grpcdebug can only print the selected section.

grpcdebug localhost:50051 xds config --type=eds
# {
#   "dynamicEndpointConfigs":  [
#     {
#       "versionInfo":  "1",
#       "endpointConfig":  {
#         "@type":  "type.googleapis.com/envoy.config.endpoint.v3.ClusterLoadAssignment",
#         "clusterName":  "cloud-internal-istio:cloud_mp_1040920224690_6530603179561593229",
#         "endpoints":  [
#           {
#             "locality":  {
#               "subZone":  "jf:us-central1-a_7062512536751318190_neg"
#             },
#             "lbEndpoints":  [
#               {
#                 "endpoint":  {
#                   "address":  {
#                     "socketAddress":  {
#                       "address":  "192.168.120.26",
#                       "portValue":  8080
#                     }
#                   }
#                 },
#                 "healthStatus":  "HEALTHY"
#               }
#             ],
#             "loadBalancingWeight":  100
#           }
#         ]
#       },
#       "lastUpdated":  "2021-03-31T01:20:33.936Z",
#       "clientStatus":  "ACKED"
#     }
#   ]
# }

Admin Services

gRPC Java:

--- a/examples/src/main/java/io/grpc/examples/helloworld/HelloWorldServer.java
+++ b/examples/src/main/java/io/grpc/examples/helloworld/HelloWorldServer.java
@@ -18,6 +18,7 @@ package io.grpc.examples.helloworld;

 import io.grpc.Server;
 import io.grpc.ServerBuilder;
+import io.grpc.services.AdminInterface;
 import io.grpc.stub.StreamObserver;
 import java.io.IOException;
 import java.util.concurrent.TimeUnit;
@@ -36,6 +37,7 @@ public class HelloWorldServer {
     int port = 50051;
     server = ServerBuilder.forPort(port)
         .addService(new GreeterImpl())
+        .addServices(AdminInterface.getStandardServices())
         .build()
         .start();
     logger.info("Server started, listening on " + port);

gRPC Go:

--- a/examples/helloworld/greeter_server/main.go
+++ b/examples/helloworld/greeter_server/main.go
@@ -27,6 +27,7 @@ import (
        "net"

        "google.golang.org/grpc"
+       "google.golang.org/grpc/admin"
        pb "google.golang.org/grpc/examples/helloworld/helloworld"
 )

@@ -51,6 +52,11 @@ func main() {
                log.Fatalf("failed to listen: %v", err)
        }
        s := grpc.NewServer()
+       cleanup, err := admin.Register(s)
+       if err != nil {
+               log.Fatalf("failed to register admin: %v", err)
+       }
+       defer cleanup()
        pb.RegisterGreeterServer(s, &server{})
        if err := s.Serve(lis); err != nil {
                log.Fatalf("failed to serve: %v", err)

gRPC C++:

--- a/examples/cpp/helloworld/greeter_server.cc
+++ b/examples/cpp/helloworld/greeter_server.cc
@@ -20,6 +20,7 @@
 #include <memory>
 #include <string>

+#include <grpcpp/ext/admin_services.h>
 #include <grpcpp/ext/proto_server_reflection_plugin.h>
 #include <grpcpp/grpcpp.h>
 #include <grpcpp/health_check_service_interface.h>
@@ -60,6 +61,7 @@ void RunServer() {
   // Register "service" as the instance through which we'll communicate with
   // clients. In this case it corresponds to an *synchronous* service.
   builder.RegisterService(&service);
+  grpc::AddAdminServices(&builder);
   // Finally assemble the server.
   std::unique_ptr<Server> server(builder.BuildAndStart());
   std::cout << "Server listening on " << server_address << std::endl;

grpc-ecosystem/grpcdebug

grpc-ecosystem

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