Envoy Proxy gRPC config in Docker

Question

I cannot seem to get this minimal Docker Envoy gRPC example to work.

Envoy config

admin:
  access_log_path: "/tmp/admin_access.log"
  address:
    socket_address: { address: "127.0.0.1", port_value: 8000 }

static_resources:
  listeners:
    - name: listener_0
      address:
        socket_address: { address: 0.0.0.0, port_value: 8080 }
      filter_chains:
        - filters:
            - name: envoy.filters.network.http_connection_manager
              typed_config:
                "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
                codec_type: AUTO
                stat_prefix: ingress_http
                route_config:
                  name: local_route
                  virtual_hosts:
                    - name: local_routes
                      domains: ["*"]
                      routes:

                        - match: { prefix: "/servers", grpc: {} } # Enable HTTP/2 for gRPC
                          route: { cluster: servers }

                        - match: { prefix: "/server1", grpc: {} } # Enable HTTP/2 for gRPC
                          route: { cluster: server1 }
                        - match: { prefix: "/server2", grpc: {} } # Enable HTTP/2 for gRPC
                          route: { cluster: server2 }

                http_filters:
                  - name: envoy.filters.http.router
                    typed_config:
                      "@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router

# LOAD BALANCING

  clusters:
    - name: servers
      connect_timeout: 1s
      type: STRICT_DNS
      lb_policy: ROUND_ROBIN
      http2_protocol_options: {} # Enable HTTP/2 for gRPC, assuming gRPC services
      load_assignment:
        cluster_name: servers
        endpoints:
          - lb_endpoints:
              - endpoint:
                  address:
                    socket_address: { address: server1, port_value: 50051 }
              - endpoint:
                  address:
                    socket_address: { address: server2, port_value: 50052 }

# ROUTING

    - name: server1
      connect_timeout: 1s
      type: STRICT_DNS
      lb_policy: ROUND_ROBIN
      http2_protocol_options: {} # Enable HTTP/2 for gRPC
      load_assignment:
        cluster_name: server1
        endpoints:
          - lb_endpoints:
              - endpoint:
                  address:
                    socket_address: { address: server1, port_value: 50051 } # server1 service address

    - name: server2
      connect_timeout: 1s
      type: STRICT_DNS
      lb_policy: ROUND_ROBIN
      http2_protocol_options: {} # Enable HTTP/2 for gRPC
      load_assignment:
        cluster_name: server2
        endpoints:
          - lb_endpoints:
              - endpoint:
                  address:
                    socket_address: { address: server2, port_value: 50052 } # server2 service address

Docker-compose config

version: '3'
services:
  
  envoy:
    image: envoyproxy/envoy:dev-2817fd926f2cac24d910d2854e8cd3a8f4537081
    ports:
      - '8080:8080'
    volumes:
      - ./envoy.yaml:/etc/envoy/envoy.yaml
    networks:
      - grpc-network
    depends_on:
      - server1
      - server2

  server1:
    build: ./server1
    ports:
      - "50051:50051"
    networks:
      - grpc-network

  server2:
    build: ./server2
    ports:
      - "50052:50051"
    networks:
      - grpc-network

networks:
  grpc-network:
    driver: bridge

Expected behavior:

• localhost:8080/servers: alternating "Hello from server 1" and "Hello from server 2" as I refresh
• localhost:8080/server1: "Hello from server 1"
• localhost:8080/server2: "Hello from server 2"

What I am getting:

• localhost:8080/servers: alternating 14 UNAVAILABLE and 12 UNIMPLEMENTED
• localhost:8080/server1: 12 UNIMPLEMENTED
• localhost:8080/server2: 14 UNAVAILABLE

When I send a request directly to the servers (without Envoy), both respond as expected.