Adding custom response headers using Istio's (1.6.0) envoy lua filter

问题

I am running Istio 1.6.0. I wanted to add some custom headers to all the outbound responses originating from my service. So I was trying to use lua envoyfilter to achieve that. However, I don't see my proxy getting properly configured.

The envoy filter config that I'm trying to use is

kind: EnvoyFilter
metadata:
  name: lua-filter
  namespace: istio-system
spec:
  workloadSelector:
    labels:
      istio: ingressgateway
  configPatches:
  - applyTo: HTTP_FILTER
    match:
      context: GATEWAY
      listener:
        filterChain:
          filter:
            name: "envoy.http_connection_manager"
            subFilter:
              name: "envoy.router"
    patch:
      operation: INSERT_BEFORE
      value:
       name: envoy.lua
       typed_config:
         "@type": "type.googleapis.com/envoy.config.filter.http.lua.v2.Lua"
         inlineCode: |
            function envoy_on_response(response_handle)
                response_handle:logInfo(" ========= XXXXX ========== ")
                response_handle:headers():add("X-User-Header", "worked")
            end

I do have my ingress-gateway pods running in the istio-system namespace

❯ kgp -l istio=ingressgateway -n istio-system
NAME                              READY   STATUS    RESTARTS   AGE
ingress-gateway-b4b5cffc9-wz75r   1/1     Running   0          3d12h
ingress-gateway-b4b5cffc9-znx9b   1/1     Running   0          28h

I was hoping that I would see X-User-Header when I curl for my service. Unfortunately, I'm not seeing any custom headers.

I tried checking the proxy-configs of the ingress-gateway pod in the istio-system, and I don't see the envoy.lua configured at all. I'm not sure whether I'm debugging it correctly.

 istioctl proxy-config listener ingress-gateway-b4b5cffc9-wz75r.istio-system  -n istio-system --port 443 -o json | grep "name"
        "name": "0.0.0.0_443",
                        "name": "istio.stats",
                        "name": "envoy.tcp_proxy",
                        "name": "istio.stats",
                        "name": "envoy.tcp_proxy",
                "name": "envoy.listener.tls_inspector",

Please let me know what is that I'm missing or incorrectly configured. Any advice on how to debug further also would be really helpful.

Thank you so much.

回答1:

As far as I checked on my istio cluster with version 1.6.3 and 1.6.4 your example works just fine. Take a look at below code from my cluster.

I checked it with curl

$ curl -s -I -X HEAD x.x.x.x/
HTTP/1.1 200 OK
server: istio-envoy
date: Mon, 06 Jul 2020 08:35:37 GMT
content-type: text/html
content-length: 13
last-modified: Thu, 02 Jul 2020 12:11:16 GMT
etag: "5efdcee4-d"
accept-ranges: bytes
x-envoy-upstream-service-time: 2
x-user-header: worked

AND

I checked it with config_dump in istio ingress-gateway pod.

I exec there with

kubectl exec -ti istio-ingressgateway-78db9f457d-xfhl7  -n istio-system -- /bin/bash

Results from config_dump

curl 0:15000/config_dump | grep X-User-Header
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  128k    0  128k    0     0  9162k      0 --:--:-- --:--:-- --:--:-- 9162k
               "inline_code": "function envoy_on_response(response_handle)\n    response_handle:logInfo(\" ========= XXXXX ========== \")\n    response_handle:headers():add(\"X-User-Header\", \"worked\")\nend\n"

So as you can see it works, header is added to request and function is active in istio ingress gateway.

Could you try to check it again with above curl, check istio ingress-gateway tcp_dump and let me know if it works for you?

来源：https://stackoverflow.com/questions/62727066/adding-custom-response-headers-using-istios-1-6-0-envoy-lua-filter

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Kubernetes

lua

Istio

envoyproxy