Override x-request-id header in istio

Question

I was trying to understand the tracing in istio.

According to istio documentation, x-request-id can be used for tracing purpose.(https://istio.io/latest/docs/tasks/observability/distributed-tracing/overview/)

I am seeing different behavior in Istio vs pure envoy proxy.

For tracing istio and also pure envoy proxy set the x-request-id. (generated guid)

However in istio the client can send a header x-request-id and the same is forwarded to the microservices.

Whereas if I have pure envoy - the x-request-id sent by the client is not considered and envoy overrides it with a generated guid.

Can istio be configured to over-ride this x-request-id if required?

Answer 1

It seems it is possible to implement using envoy filter only. This is not my solution - I found it, however it looks very promising and maybe resolve your issue.

Please take a look at Istio EnvoyFilter to add x-request-id to all responses

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: gateway-response
  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_request(handle)
             local metadata = handle:streamInfo():dynamicMetadata()
             local headers = handle:headers()
             local rid = headers:get("x-request-id")

             -- for key, value in pairs(handle:headers()) do
             --   handle:logTrace("key:" .. key .. " <--> value:" .. value)
             -- end

             if rid ~= nil then
               metadata:set("envoy.filters.http.lua", "req.x-request-id", rid)
             end
           end

           function envoy_on_response(handle)
             local metadata = handle:streamInfo():dynamicMetadata():get("envoy.filters.http.lua")
             local rid = metadata["req.x-request-id"]
             if rid ~= nil then
               handle:headers():add("x-request-id", rid)
             end
           end

---

And second one - just my assumption..

maybe you can try to add the x-request-id in the header of VirtualService? virtualservice-headers