Failed to debug grpc channelz with web tool - grpc

Question

In this doc A short introduction to Channelz, there is a web tool called grpc-zpages conveniently serve channelz data through a web page.
However, we cannot find any TopChannels data from this web tool. Does someone meet the same issue?
To make this web tool run, there are some changes to the codes
Add the following codes to http_filters of zprox.sh
function envoy_on_response(response_handle)
filter_name = "ENVOY"
response_handle:headers():add("my_Filter", filter_name)
end
to solve the error envoy_on_response() function not found. lua filter will not hook responses
Comment network_mode: 'host' of start_docker.sh to solve the error docker.errors.InvalidArgument: "host" network_mode is incompatible with port_bindings
Replace manual.GenerateAndRegisterManualResolver() with
r := manual.NewBuilderWithScheme("whatever")
r.InitialState(resolver.State{Addresses: []resolver.Address{{Addr: ":10001"}, {Addr: ":10002"}, {Addr: ":10003"}}})
// Set up a connection to the server.
conn, err := grpc.Dial(r.Scheme()+":///test.server",
grpc.WithInsecure(),
grpc.WithResolvers(r),
grpc.WithDefaultServiceConfig(`{"loadBalancingPolicy":"round_robin"}`),
)
under grpc 1.37.1

Answer 1

Please make sure you had added channelz service and reflection service to the server. If your service is a client, you need to make the client has a grpc server also. After call server and the channel is connected, the related data could be fetched.
The grpc-zpages is not maintain anymore, and it is hard to use. I suggest to use channelzcli replace.

Answer 2

I also had trouble using the web tool and ended up using grpcurl.
One thing that took me a while to realize is that in order to activate channelz on your grpc client you need to run a grpc server and enable channelz on your client service alongside your grpc client
Some grpcurl useful commands for Channelz:
Query for the Channelz service API, to see all available methods:
grpcurl -plaintext -msg-template localhost:50052 describe grpc.channelz.v1.Channelz
Query method template to understand what parameters it requires:
grpcurl -plaintext -msg-template localhost:50052 describe .grpc.channelz.v1.GetSocketReques
Client commands examples (make sure to use the client port):
grpcurl -plaintext localhost:50052 grpc.channelz.v1.Channelz/GetTopChannels
grpcurl -plaintext -d '{"subchannel_id":"14"}' localhost:50052 grpc.channelz.v1.Channelz/GetSubchannel
grpcurl -plaintext -d '{"socket_id":"34"}' localhost:50052 grpc.channelz.v1.Channelz/GetSocket
Server commands (make sure to use the server port):
grpcurl -plaintext localhost:50051 grpc.channelz.v1.Channelz/GetServers
grpcurl -plaintext -d '{"server_id":"2"}' localhost:50051 grpc.channelz.v1.Channelz/GetServerSockets
grpcurl -plaintext -d '{"socket_id":"21"}' localhost:50051 grpc.channelz.v1.Channelz/GetSocket