Updating to 0.3.0-alpha.1 breaks connection

[ospaarmann]

When upgrading from master on GitHub to 0.3.0-alpha.1 and running my client again I encounter a couple of new errors when trying to connect to a Server (Dgraph) using GRPC:

** (KeyError) key :code not found in: %CaseClauseError{term: {:error, %GRPC.RPCError{message: "{:stream_error, :protocol_error, :\"Malformed response; missing :status in HEADERS frame. (RFC7540 8.1.2.4)\"}", status: 2}}}

** (MatchError) no match of right hand side value: {:error, [code: 2, message: "{:connection_error, :compression_error, :\"Error while trying to decode HPACK-encoded header block. (RFC7540 4.3)\"}"]}

** (MatchError) no match of right hand side value: {:error, [code: 2, message: ":noproc"]}

** (MatchError) no match of right hand side value: {:error, [code: 13, message: "shouldn't finish when getting headers"]}

I tried upgrading protobuf-elixir and protoc-gen-elixir. No luck.

Before I start digging into my code: Any idea what is going on here?

Thank you!

[tony612]

Could you see the stacktrace? One strange thing is grpc-elixir doesn't use code, which in your errors looks like status of GPRC.RPCError.

[tony612]

btw, what's the version of gun in your mix.lock?

[tony612]

Please try lock your gun at 1.0.0-pre.5. I just realized that 1.0.0-pre.4b is newer than 1.0.0-pre.5 on hex, which is weird.

[ospaarmann]

I seem to have both versions in my mix.lock

"grpc": {:hex, :grpc, "0.3.0-alpha.1", "a43385d5b1974341fc4751b090b6528986f693d9637b8854de1dec14399e8cee", [:mix], [{:cowboy, "~> 2.2", [hex: :cowboy, repo: "hexpm", optional: false]}, {:gun, ">= 1.0.0-pre.5", [hex: :gun, repo: "hexpm", optional: false]}, {:protobuf, "~> 0.5", [hex: :protobuf, repo: "hexpm", optional: false]}], "hexpm"},
"gun": {:hex, :gun, "1.0.0-pre.4b", "dd53b9fd3d597cfa7974d6ad85128ac7e16a408d6dc8c392a532aa36eb032a5d", [:rebar3], [{:cowlib, "2.1.0", [hex: :cowlib, repo: "hexpm", optional: false]}, {:ranch, "1.4.0", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm"}

Locking gun to 1.0.0-pre.5 got rid of the errors above. Now still some of my tests are failing with

%GRPC.RPCError{message: "shouldn't finish when getting headers", status: 13}

So it's an improvement 😄. Btw. my deps in mix.exs looks like this now:

defp deps do
    [
      {:grpc, "~> 0.3.0-alpha.1"},
      {:gun, "1.0.0-pre.5", override: true},
      {:protobuf, "~> 0.5"},
      {:poison, "~> 3.1"},
      {:poolboy, "~> 1.5.1"},
      {:db_connection, "~> 1.1"},
      {:retry, "~> 0.8"},
      {:uuid, "~> 1.1"},
      {:morphix, "~> 0.2.1"},
      {:ex_doc, "~> 0.16", only: :dev, runtime: false},
      {:mix_test_watch, "~> 0.5", only: :dev, runtime: false},
      {:excoveralls, "~> 0.8", only: :test}
    ]
  end 

I could push the current changes to a feature branch for my client if this helps you. I don't have any further stacktrace at this point.

Thanks!

[ospaarmann]

I have published the feature branch with the described behaviour: https://github.com/ospaarmann/exdgraph/tree/use_grpc_hex_package

[tony612]

What's your function call when you got the error? Could you point out the code? I found it's a little complex to run dgraph 😂

[tony612]

If possible, could you captures packages and send the file to me? I wrote a wiki about this https://github.com/tony612/grpc-elixir/wiki/How-to-capture-HTTP-2-packages-using-Wireshark

[tony612]

I guess I known the reason, the server side returns error directly. You can add these two code

        IO.inspect(status)
        IO.inspect(headers)

before this line https://github.com/tony612/grpc-elixir/blame/master/lib/grpc/adapter/gun.ex#L130 in deps/grpc. Then run mix deps.compile grpc to see what's the status.

I'll improve the error message in the next release.

[ospaarmann]

Hey,

I tried logging status and headers as you advised. But nothing showed up when running the tests. I also added another IO.puts/1 call to make sure they weren't just nil. Still no output at all.

This is the changed code in /lib/grpc/adapter/gun.ex. And yes, I recompiled everything running mix clean mix deps.compile grpc and mix compile.

defp await(conn_pid, stream_ref, timeout) do
    case :gun.await(conn_pid, stream_ref, timeout) do
      {:response, :fin, status, headers} ->
        IO.puts("GUN ERROR")
        IO.inspect(status)
        IO.inspect(headers)

        {:error,
         GRPC.RPCError.exception(GRPC.Status.internal(), "shouldn't finish when getting headers")}

      {:response, :nofin, status, headers} ->
        if status == 200 do
          {:response, headers}
        else
          {:error, GRPC.RPCError.exception(GRPC.Status.internal(), "status got is not 200")}
        end

      {:data, :fin, _} ->
        {:error,
         GRPC.RPCError.exception(GRPC.Status.internal(), "shouldn't finish when getting data")}

      {:data, :nofin, data} ->
        {:data, data}

      trailers = {:trailers, _} ->
        trailers

      {:error, :timeout} ->
        {:error, GRPC.RPCError.exception(GRPC.Status.deadline_exceeded(), "deadline exceeded")}

      {:error, {reason, msg}} ->
        {:error, GRPC.RPCError.exception(GRPC.Status.unknown(), "#{reason}: #{msg}")}

      {:error, reason} ->
        {:error, GRPC.RPCError.exception(GRPC.Status.unknown(), "#{inspect(reason)}")}

      other ->
        {:error,
         GRPC.RPCError.exception(
           GRPC.Status.unknown(),
           "unexpected message when waiting: #{inspect(other)}"
         )}
    end
  end

Strange thing though: When I changed the error message in the code itself it didn't change in the output.

[ospaarmann]

On further inspection: My bad. I had to run MIX_ENV=test mix deps.compile grpc to make the changes show up in my tests.

I receive the following errors ("GUN ERROR" comes from me...):

GUN ERROR
200
[
  {"content-type", "application/grpc"},
  {"grpc-status", "2"},
  {"grpc-message", "while lexing INVALID: Invalid operation type: INVALID"}
]
GUN ERROR
200
[
  {"content-type", "application/grpc"},
  {"grpc-status", "2"},
  {"grpc-message", "while lexing INVALID: Invalid operation type: INVALID"}
]

So the server actually returns what I am waiting for but it is not passed on or something.

[tony612]

Okay. I knew this issue already, it'll be fixed later.

[ospaarmann]

Very nice! Do you have an aprox. timeline for the fix? Can I support you? Thanks!

[tony612]

@ospaarmann Could you try the master branch?

[ospaarmann]

@tony612 I now receive new errors in my tests:

{:error,
 %ArgumentError{
   message: "the Access calls for keywords expect the key to be an atom, got: \"grpc-status\""
 }}

[tony612]

@ospaarmann Try again? I need to add more tests 😅

[ospaarmann]

Yes. That works now! 💯

[ospaarmann]

@tony612 In which Hex release will this fix be included? Would be great to know so I can go forward publishing my package. Thanks.

[tony612]

@ospaarmann I plan to release a new version in this week after some issues I already know are fixed.

[tony612]

@ospaarmann 0.3.0-alpha.2 is released.

[ospaarmann]

@tony612 Any timeline for a stable / non-alpha release? Still cannot publish my package with a pre-release dependency.

[tony612]

One problem is gun, which grpc depends on, is not stable. Do you use client, server side or both? On Thu, Apr 26, 2018 at 05:44 Ole Spaarmann notifications@github.com wrote:

@tony612 https://github.com/tony612 Any timeline for a stable / non-alpha release? Still cannot publish my package with a pre-release dependency.

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[ospaarmann]

Client side. It is a database client for Dgraph. I now published it also as pre-release on hex.pm.