[k8s] The configuration file for the custom nginx.conf example in GKE (with gRPC) is invalid.

[isbee]

The current document provides a nginx.conf file that does not support gRPC. (And endpoints-samples/k8s/ does not contains such .conf)

nginx.conf that supports gRPC should look something like this (auto-generated by start_esp):

# Auto-generated by start_esp
# Copyright 2017 Google Inc.
#
# 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.

daemon off;

user nginx nginx;

pid /var/run/nginx.pid;

# Worker/connection processing limits
worker_processes 1;
worker_rlimit_nofile 10240;
events { worker_connections 10240; }

# Logging to stderr enables better integration with Docker and GKE/Kubernetes.
error_log stderr warn;

http {
  include /etc/nginx/mime.types;
  server_tokens off;
  client_max_body_size 32m;
  client_body_buffer_size 128k;

  # HTTP subrequests
  endpoints_resolver 8.8.8.8;
  endpoints_certificates /etc/nginx/trusted-ca-certificates.crt;

  set_real_ip_from  0.0.0.0/0;
  set_real_ip_from  0::/0;
  real_ip_header    X-Forwarded-For;
  real_ip_recursive on;

  server {
    server_name "";

    listen 9000 http2 backlog=16384;

    access_log /dev/stdout;

    location / {
      # Begin Endpoints v2 Support
      endpoints {
        on;
        server_config /etc/nginx/server_config.pb.txt;
        metadata_server http://169.254.169.254;
      }
      # End Endpoints v2 Support

      # WARNING: only first backend is used
      grpc_pass 127.0.0.1:8000 override;
    }

    include /var/lib/nginx/extra/*.conf;
  }

  server {
    # expose /nginx_status and /endpoints_status but on a different port to
    # avoid external visibility / conflicts with the app.
    listen 8090;
    location /nginx_status {
      stub_status on;
      access_log off;
    }
    location /endpoints_status {
      endpoints_status;
      access_log off;
    }
    location /healthz {
      return 200;
      access_log off;
    }
    location / {
      root /dev/null;
    }
  }
}

So I suggest adding the above .conf file.