将 Envoy 配置为边缘代理¶

Envoy 是一个生产就绪的边缘代理，然而，默认配置是为服务网格用例定制的，当需要将 Envoy 当作边缘代理使用时，一些值需要做一些调整。

TCP 代理应该做如下配置：

对于 admin 端点的限制访问，
overload_manager ，
监听器缓冲限制的值为 32 KiB，
集群缓冲限制的值为 32 KiB。

HTTP 代理还应做如下额外的配置：

use_remote_address 的值为 true (为了避免消耗外部客户端的 HTTP 头部，详情可看 HTTP header 消耗 )，
连接和流超时，
HTTP/2 最大并发流限制的值为 100，
HTTP/2 初始流窗口大小限制的值为 64 KiB，
HTTP/2 初始连接窗口大小限制的值为 1 MiB。
headers_with_underscores_action 设置的值为 REJECT_REQUEST，为了防止上游服务认为 ‘_’ 和 ‘-‘ 是可互换的。
监听器连接限制。
全局下游连接限制。

下面内容是上述建议配置的一个 YAML 示例（摘自 Google VRP 边缘服务器配置）：

overload_manager:
  refresh_interval: 0.25s
  resource_monitors:
  - name: "envoy.resource_monitors.fixed_heap"
    typed_config:
      "@type": type.googleapis.com/envoy.config.resource_monitor.fixed_heap.v2alpha.FixedHeapConfig
      # TODO: Tune for your system.
      max_heap_size_bytes: 2147483648 # 2 GiB
  actions:
  - name: "envoy.overload_actions.shrink_heap"
    triggers:
    - name: "envoy.resource_monitors.fixed_heap"
      threshold:
        value: 0.95
  - name: "envoy.overload_actions.stop_accepting_requests"
    triggers:
    - name: "envoy.resource_monitors.fixed_heap"
      threshold:
        value: 0.98

admin:
  access_log_path: "/var/log/envoy_admin.log"
  address:
    socket_address:
      address: 127.0.0.1
      port_value: 9090

static_resources:
  listeners:
  - address:
      socket_address:
        address: 0.0.0.0
        port_value: 443
    listener_filters:
    - name: "envoy.filters.listener.tls_inspector"
      typed_config: {}
    per_connection_buffer_limit_bytes: 32768 # 32 KiB
    filter_chains:
    - filter_chain_match:
        server_names: ["example.com", "www.example.com"]
      transport_socket:
        name: envoy.transport_sockets.tls
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.transport_sockets.tls.v3.DownstreamTlsContext
          common_tls_context:
            tls_certificates:
            - certificate_chain: { filename: "certs/servercert.pem" }
              private_key: { filename: "certs/serverkey.pem" }
      # Uncomment if Envoy is behind a load balancer that exposes client IP address using the PROXY protocol.
      # use_proxy_proto: true
      filters:
      - name: envoy.filters.network.http_connection_manager
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
          stat_prefix: ingress_http
          use_remote_address: true
          common_http_protocol_options:
            idle_timeout: 3600s # 1 hour
            headers_with_underscores_action: REJECT_REQUEST
          http2_protocol_options:
            max_concurrent_streams: 100
            initial_stream_window_size: 65536 # 64 KiB
            initial_connection_window_size: 1048576 # 1 MiB
          stream_idle_timeout: 300s # 5 mins, must be disabled for long-lived and streaming requests
          request_timeout: 300s # 5 mins, must be disabled for long-lived and streaming requests
          route_config:
            virtual_hosts:
            - name: default
              domains: "*"
              routes:
              - match: { prefix: "/" }
                route:
                  cluster: service_foo
                  idle_timeout: 15s # must be disabled for long-lived and streaming requests
  clusters:
    name: service_foo
    connect_timeout: 15s
    per_connection_buffer_limit_bytes: 32768 # 32 KiB
    load_assignment:
      cluster_name: some_service
      endpoints:
        - lb_endpoints:
          - endpoint:
              address:
                socket_address:
                  address: 127.0.0.1
                  port_value: 8080
    http2_protocol_options:
      initial_stream_window_size: 65536 # 64 KiB
      initial_connection_window_size: 1048576 # 1 MiB

layered_runtime:
  layers:
    - name: static_layer_0
      static_layer:
        envoy:
          resource_limits:
            listener:
              example_listener_name:
                connection_limit: 10000
        overload:
          global_downstream_max_connections: 50000