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Yuchen Dai edited this page Mar 15, 2022 · 17 revisions

EnvoyFilter

This doc showcases some example EnvoyFilter configs. Use at your own risk; see warnings on the docs before using any of these.

HTTP2 Flow Control

Warning: this example may break websocket traffic since websocket or other requests that require http 1 codec. More precise matcher is required, including but not limited to

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: h2-control
spec:
  configPatches:
  - applyTo: CLUSTER
    patch:
      operation: MERGE
      value:
        http2_protocol_options:
          initial_stream_window_size: 65536
          initial_connection_window_size: 65536
  - applyTo: NETWORK_FILTER
    match:      
      listener:
        filterChain:
          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"
          http2_protocol_options:
            initial_stream_window_size: 65536
            initial_connection_window_size: 65536

Tracing and Access Logging

Note: Upcoming (1.9, 1.10?) Istio Telemetry API will provide a first class way to configure access logs and traces. It is recommended to use that method when it is available, until then EnvoyFilter will do.

Disable access logging at sidecars and only enable it at gateways.

  1. Disable access logging globally.
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  profile: default
  meshConfig:
    accessLogFile: ""
  1. Use EnvoyFilter configuration to selectively enable access logs at gateways. (Tested with 1.8)
apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: gateway-access-log
  namespace: istio-system
spec:
  configPatches:
  - applyTo: NETWORK_FILTER
    match:
      context: GATEWAY
      listener:
        filterChain:
          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"
          access_log:
          - name: envoy.access_loggers.file
            typed_config:
              "@type": "type.googleapis.com/envoy.extensions.access_loggers.file.v3.FileAccessLog"
              path: /dev/stdout
              format: "[%START_TIME%] \"%REQ(:METHOD)% %REQ(X-ENVOY-ORIGINAL-PATH?:PATH)% %PROTOCOL%\" %RESPONSE_CODE% %RESPONSE_FLAGS% \n"

If you want the default format, take a look full access format.

Configure 100% trace sampling and change log format.

Here we are setting up a 100% random sampling rate at each sidecar within the mesh, as well as turning on access logging with a custom log format. An additional config is added for configuring route-level tracing at the gateway.

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: access-log
spec:
  configPatches:
  - applyTo: NETWORK_FILTER
    match:
      context: ANY
      listener:
        filterChain:
          filter:
            name: "envoy.http_connection_manager"
    patch:
      operation: MERGE
      value:
        typed_config:
          "@type": "type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager"
          tracing:
            random_sampling:
              value: 100
          access_log:
          - name: envoy.file_access_log
            typed_config:
              "@type": "type.googleapis.com/envoy.extensions.access_loggers.file.v3.FileAccessLog"
              path: /dev/stdout
              format: "%REQ(:METHOD)% %PROTOCOL% %RESPONSE_CODE% %RESPONSE_FLAGS%\n"
---
apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: bookinfo-gateway-sampling
  namespace: istio-system
spec:
  configPatches:
  - applyTo: HTTP_ROUTE
    match:
      context: GATEWAY
      routeConfiguration:
        portNumber: 80
        vhost:
          name: "*:80"
    patch:
      operation: MERGE
      value:
        tracing:
          random_sampling:
            numerator: 9990
            denominator: TEN_THOUSAND

Use Remote Address and XFF Num Trust Hops

The following example configures Envoy to add or append the client IP address to the X-Forwarded-For header. This is typically used at the Gateway Envoy so that the receiving application can obtain the client's IP address from the X-Forwarded-For header. See https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_conn_man/headers#x-forwarded-for for more details.

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: xff
  namespace: istio-system
spec:
  configPatches:
  - applyTo: NETWORK_FILTER
    match:
      context: ANY
      listener:
        filterChain:
          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"
          use_remote_address: true
          xff_num_trusted_hops: 1

Adding a HTTP Lua filter

The following example enables Envoy's Lua filter for all inbound HTTP calls arriving at service port 8080 of the reviews service pod with labels "app: reviews", in the bookinfo namespace. The lua filter calls out to an external service internal.org.net:8888 that requires a special cluster definition in envoy. The cluster is also added to the sidecar as part of this configuration.

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.lua
       typed_config:
          "@type": "type.googleapis.com/envoy.extensions.filters.http.lua.v3.Lua"
          inlineCode: |
            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

Preserve HTTP Header Casing

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: header-casing
spec:
  configPatches:
  - applyTo: CLUSTER
    match:
      cluster:
      context: SIDECAR_INBOUND
    patch:
      operation: MERGE
      value:
        typed_extension_protocol_options:
          envoy.extensions.upstreams.http.v3.HttpProtocolOptions:
            '@type': type.googleapis.com/envoy.extensions.upstreams.http.v3.HttpProtocolOptions
            use_downstream_protocol_config:
              http_protocol_options:
                header_key_format:
                  stateful_formatter:
                    name: preserve_case
                    typed_config:
                      '@type': type.googleapis.com/envoy.extensions.http.header_formatters.preserve_case.v3.PreserveCaseFormatterConfig
  - applyTo: NETWORK_FILTER
    match:
      listener:
        filterChain:
          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
          http_protocol_options:
            header_key_format:
              stateful_formatter:
                name: preserve_case
                typed_config:
                  '@type': type.googleapis.com/envoy.extensions.http.header_formatters.preserve_case.v3.PreserveCaseFormatterConfig

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