Empty reply from server

I’m trying to run the gateway in a Docker container, following the instructions in the Dockerfile itself. I’ve pulled the repo down, and here the relevant excerpt from my Compose file.

  grpc-web:
    build:
      context: grpc-web
      dockerfile: net/grpc/gateway/docker/ubuntu_16_04/Dockerfile
    ports:
      - "9091:9091"
    links:
      - app-server:localhost
    command: sh -c "cd /github/grpc-web/gConnector && ./nginx.sh"

When the container starts, I get the following output:

grpc-web_1      | nginx: [alert] could not open error log file: open() "./logs/error.log" failed (2: No such file or directory)
grpc-web_1      | 2018/02/27 22:07:58 [notice] 7#0: using the "epoll" event method
grpc-web_1      | 2018/02/27 22:07:58 [notice] 7#0: nginx/1.11.13
grpc-web_1      | 2018/02/27 22:07:58 [notice] 7#0: built by gcc 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.9) 
grpc-web_1      | 2018/02/27 22:07:58 [notice] 7#0: OS: Linux 4.9.60-linuxkit-aufs
grpc-web_1      | 2018/02/27 22:07:58 [notice] 7#0: getrlimit(RLIMIT_NOFILE): 1048576:1048576
grpc-web_1      | I0227 22:07:58.939213904       7 grpc_event_queue.cc:44]     GRPC event thread started: 1

But when I make a request like this:

$ curl 'http://localhost:9091/helloworld.Greeter/SayHello' -H 'content-type: application/grpc-web+proto' -H 'x-grpc-web: 1' -H 'authority: localhost:9091' --data-binary $'\x00\x00\x00\x00\x04\n\x02yo' --insecure -v
*   Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 9091 (#0)
> POST /helloworld.Greeter/SayHello HTTP/1.1
> Host: localhost:9091
> User-Agent: curl/7.54.0
> Accept: */*
> content-type: application/grpc-web+proto
> x-grpc-web: 1
> authority: localhost:9091
> Content-Length: 0
> 
* Empty reply from server
* Connection #0 to host localhost left intact
curl: (52) Empty reply from server

As you can see, I get no response. And nothing shows up in the console. My gRPC server is running and listening on port 9090. Is there an issue with my config?

[jonahbron]

@fengli79 That makes sense. I think this has to do with bash strings using null bytes as the ending character.

https://unix.stackexchange.com/questions/174016/how-do-i-use-null-bytes-in-bash

I found a workaround in bash to avoid ever storing the request body in a bash string:

printf '\x00\x00\x00\x00\x04\n\x02yo' | curl -skv 'http://localhost:9091/helloworld.Greeter/SayHello' -H 'content-type: application/grpc-web+proto' -H 'x-grpc-web: 1' -H 'authority: localhost:9091' -H 'accept: application/grpc-web-text' --data-binary @- | base64 --decode
*   Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 9091 (#0)
> POST /helloworld.Greeter/SayHello HTTP/1.1
> Host: localhost:9091
> User-Agent: curl/7.54.0
> content-type: application/grpc-web+proto
> x-grpc-web: 1
> authority: localhost:9091
> accept: application/grpc-web-text
> Content-Length: 9
> 
} [9 bytes data]
* upload completely sent off: 9 out of 9 bytes
< HTTP/1.1 200 OK
< Server: nginx/1.11.13
< Date: Wed, 28 Feb 2018 19:35:41 GMT
< Transfer-Encoding: chunked
< Connection: keep-alive
< content-type: application/grpc-web-text
< Access-Control-Allow-Origin: *
< Access-Control-Allow-Methods: GET, POST, OPTIONS
< Access-Control-Allow-Headers: DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Transfer-Encoding,Custom-Header-1,X-Accept-Content-Transfer-Encoding,X-Accept-Response-Streaming
< Access-Control-Expose-Headers: Content-Transfer-Encoding
< 
{ [151 bytes data]
* Connection #0 to host localhost left intact
?bgrpc-status: 13
grpc-message: Receiving initial metadata for GRPC response from backend failed.

I’m still not getting any console output from my backend server, so it seems like the gateway isn’t talking to it.

[jonahbron]

@stanley-cheung PR #155 added, thanks very much.