Configuring Envoy as an edge proxy

Envoy is a production-ready edge proxy, however, the default settings are tailored for the service mesh use case, and some values need to be adjusted when using Envoy as an edge proxy.

TCP proxies should configure:

• restrict access to the admin endpoint,

• overload_manager,

• listener buffer limits to 32 KiB,

• cluster buffer limits to 32 KiB.

HTTP proxies should additionally configure:

• use_remote_address to true (to avoid consuming HTTP headers from external clients, see HTTP header sanitizing for details),

• connection and stream timeouts,

• HTTP/2 maximum concurrent streams limit to 100,

• HTTP/2 initial stream window size limit to 64 KiB,

• HTTP/2 initial connection window size limit to 1 MiB.

• headers_with_underscores_action setting to REJECT_REQUEST, to protect upstream services that treat ‘_’ and ‘-‘ as interchangeable.

• Listener connection limits.

• Global downstream connection limits.

The following is a YAML example of the above recommendation (taken from the Google VRP edge server configuration):

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: "example_com_cert.pem" }
              private_key: { filename: "example_com_key.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