Connecting react web client to gRPC server through Envoy docker doesn't work

Question

I have gRPC server in scala Play Framework which exposes gRPC hello world example service on port 9000. I'm trying to connect it with React web client. It seems that I'm having connection issues with Envoy proxy which is deployed to docker container on Mac.

I'm always getting the same error which I believe means that Envoy is not able to connect with backend:

​code: 2​
message: "Http response at 400 or 500 level"
​metadata: Object {  }

My docker file to build Envoy is:

FROM envoyproxy/envoy:v1.12.2
COPY ./envoy.yaml /etc/envoy/envoy.yaml
CMD /usr/local/bin/envoy -c /etc/envoy/envoy.yaml -l trace --log-path /tmp/envoy_info.log

And I'm building it using this script:

echo --- Building my-envoy docker image ---
docker build -t my-envoy:1.0 .

echo --- Running my-envoy docker image ---
docker run -d -p 8080:8080 -p 9901:9901 --network=host my-envoy:1.0

Envoy configuration is defined in this yaml file:

admin:
  access_log_path: /tmp/admin_access.log
  address:
    socket_address: { address: 0.0.0.0, port_value: 9901 }

static_resources:
  listeners:
    - name: listener_0
      address:
        socket_address: { address: 0.0.0.0, port_value: 8080 }
      filter_chains:
        - filters:
            - name: envoy.http_connection_manager
              config:
                codec_type: auto
                stat_prefix: ingress_http
                route_config:
                  name: local_route
                  virtual_hosts:
                    - name: local_service
                      domains: ["*"]
                      routes:
                        - match: { prefix: "/" }
                          route:
                            cluster: greeter_service
                            max_grpc_timeout: 0s
                      cors:
                        allow_origin:
                          - "*"
                        allow_methods: GET, PUT, DELETE, POST, OPTIONS
                        allow_headers: keep-alive,user-agent,cache-control,content-type,content-transfer-encoding,custom-header-1,x-accept-content-transfer-encoding,x-accept-response-streaming,x-user-agent,x-grpc-web,grpc-timeout
                        max_age: "1728000"
                        expose_headers: custom-header-1,grpc-status,grpc-message
                http_filters:
                  - name: envoy.grpc_web
                  - name: envoy.cors
                  - name: envoy.router
  clusters:
    - name: greeter_service
      connect_timeout: 0.25s
      type: logical_dns
      http2_protocol_options: {}
      lb_policy: round_robin
      hosts: [{ socket_address: { address: host.docker.internal, port_value: 9000 }}]

I could not find anything relevant in envoy log file except these logs:

[2020-12-15 01:28:18.747][8][debug][upstream] [source/common/upstream/logical_dns_cluster.cc:72] starting async DNS resolution for host.docker.internal
[2020-12-15 01:28:18.747][8][trace][upstream] [source/common/network/dns_impl.cc:160] Setting DNS resolution timer for 5000 milliseconds
[2020-12-15 01:28:18.748][8][trace][upstream] [source/common/network/dns_impl.cc:160] Setting DNS resolution timer for 5000 milliseconds
[2020-12-15 01:28:18.749][8][debug][upstream] [source/common/upstream/logical_dns_cluster.cc:79] async DNS resolution complete for host.docker.internal
[2020-12-15 01:28:21.847][8][debug][main] [source/server/server.cc:175] flushing stats
[2020-12-15 01:28:23.751][8][debug][upstream] [source/common/upstream/logical_dns_cluster.cc:72] starting async DNS resolution for host.docker.internal
[2020-12-15 01:28:23.751][8][trace][upstream] [source/common/network/dns_impl.cc:160] Setting DNS resolution timer for 5000 milliseconds
[2020-12-15 01:28:23.753][8][trace][upstream] [source/common/network/dns_impl.cc:160] Setting DNS resolution timer for 5000 milliseconds
[2020-12-15 01:28:23.753][8][debug][upstream] [source/common/upstream/logical_dns_cluster.cc:79] async DNS resolution complete for host.docker.internal