概述

EnvoyFilter提供了定制化修改服务网格数据面配置的能力，通过EnvoyFilter可以实现修改某个数据面配置字段、添加或修改过滤器、监听器、集群等配置，功能十分强大，所以在使用改功能时必须小心，确保对数据面配置有比较深入的理解；错误的配置可能影响网格数据面的稳定性。

对于任何数据面，允许存在多个EnvoyFilter匹配该数据面，位于根命名空间的EnvoyFilter优先级最高，其次是位于数据面所在的命名空间的EnvoyFilter。

注意
EnvoyFilter API和服务网格底层实现耦合较为紧密，在升级网格版本的时候需要关注已经定义的EnvoyFilter版本和新版本的网格是否存在兼容性问题
多个EnvoyFilter匹配同一个数据面时，生效的优先级为根命名空间下的EnvoyFilter优先级最高，其他的按照创建时间顺序生效；如果EnvoyFilter之间存在冲突，结果是未定义的
需要配置EnvoyFilter匹配不同的工作负载时（比如网关和sidecar），可以考虑在根命名空间下定义，且不配置workloadselector

配置示例

配置示例一

在根命名空间下创建全局生效的EnvoyFilter，在sidecar outbound方向9307端口的tcp proxy插件之前插入mongo的代理配置；为所有数据面（网关和sidecar）的HttpConnectionManager插件配置HTTP空闲连接时间为30秒。

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: custom-protocol
  namespace: istio-system # as defined in meshConfig resource.
spec:
  configPatches:
  - applyTo: NETWORK_FILTER
    match:
      context: SIDECAR_OUTBOUND # will match outbound listeners in all sidecars
      listener:
        portNumber: 9307
        filterChain:
          filter:
            name: "envoy.filters.network.tcp_proxy"
    patch:
      operation: INSERT_BEFORE
      value:
        # This is the full filter config including the name and typed_config section.
        name: "envoy.extensions.filters.network.mongo_proxy"
        typed_config:
          "@type": "type.googleapis.com/envoy.extensions.filters.network.mongo_proxy.v3.MongoProxy"
          ...
  - applyTo: NETWORK_FILTER # http connection manager is a filter in Envoy
    match:
      # context omitted so that this applies to both sidecars and gateways
      listener:
        filterChain:
          filter:
            name: "envoy.filters.network.http_connection_manager"
    patch:
      operation: MERGE
      value:
        name: "envoy.filters.network.http_connection_manager"
        typed_config:
          "@type": "type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager"
          common_http_protocol_options:
            idle_timeout: 30s

配置示例二

为bookinfo命名空间下匹配标签app: reviews的工作负载下发自定义配置，在sidecar入站方向HttpConnectionManager中的最后一个Router插件之前插入lua插件，在收到请求后会执行lua代码调用一个外部授权服务；这个外部授权服务通过一个外部域名标识，也通过配置下发到数据面

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: reviews-lua
  namespace: bookinfo
spec:
  workloadSelector:
    labels:
      app: reviews
  configPatches:
    # The first patch adds the lua filter to the listener/http connection manager
  - applyTo: HTTP_FILTER
    match:
      context: SIDECAR_INBOUND
      listener:
        portNumber: 8080
        filterChain:
          filter:
            name: "envoy.filters.network.http_connection_manager"
            subFilter:
              name: "envoy.filters.http.router"
    patch:
      operation: INSERT_BEFORE
      value: # lua filter specification
       name: envoy.filters.http.lua
       typed_config:
          "@type": "type.googleapis.com/envoy.extensions.filters.http.lua.v3.Lua"
          defaultSourceCode:
            inlineString: |
              function envoy_on_request(request_handle)
                -- Make an HTTP call to an upstream host with the following headers, body, and timeout.
                local headers, body = request_handle:httpCall(
                 "lua_cluster",
                 {
                  [":method"] = "POST",
                  [":path"] = "/acl",
                  [":authority"] = "internal.org.net"
                 },
                "authorize call",
                5000)
              end
  # The second patch adds the cluster that is referenced by the lua code
  # cds match is omitted as a new cluster is being added
  - applyTo: CLUSTER
    match:
      context: SIDECAR_OUTBOUND
    patch:
      operation: ADD
      value: # cluster specification
        name: "lua_cluster"
        type: STRICT_DNS
        connect_timeout: 0.5s
        lb_policy: ROUND_ROBIN
        load_assignment:
          cluster_name: lua_cluster
          endpoints:
          - lb_endpoints:
            - endpoint:
                address:
                  socket_address:
                    protocol: TCP
                    address: "internal.org.net"
                    port_value: 8888

配置示例三

为根命名空间下匹配istio: ingressgateway标签的网关下发自定义配置，当请求sni是app.example.com时给HttpConnectionManager配置HTTP空闲连接时间和XFF信任的跳数

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: hcm-tweaks
  namespace: istio-system
spec:
  workloadSelector:
    labels:
      istio: ingressgateway
  configPatches:
  - applyTo: NETWORK_FILTER # http connection manager is a filter in Envoy
    match:
      context: GATEWAY
      listener:
        filterChain:
          sni: app.example.com
          filter:
            name: "envoy.filters.network.http_connection_manager"
    patch:
      operation: MERGE
      value:
        typed_config:
          "@type": "type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager"
          xff_num_trusted_hops: 5
          common_http_protocol_options:
            idle_timeout: 30s

配置说明

EnvoyFilter

EnvoyFilter.EnvoyConfigObjectPatch

EnvoyFilter.EnvoyConfigObjectMatch

Envoy过滤器匹配条件

EnvoyFilter.ProxyMatch

EnvoyFilter.ListenerMatch

EnvoyFilter.ListenerMatch.FilterChainMatch

存在多个filter chain的情况下可以用于匹配特定filter chain

EnvoyFilter.ListenerMatch.FilterMatch

EnvoyFilter.ListenerMatch.SubFilterMatch

EnvoyFilter.RouteConfigurationMatch

EnvoyFilter.RouteConfigurationMatch.VirtualHostMatch

EnvoyFilter.RouteConfigurationMatch.RouteMatch

EnvoyFilter.ClusterMatch