Add X-VCAP-REQUEST-ID HTTP Headers.

Learn how to add additional Cloud Foundry style headers to your gateways.

Kf limits the headers it returns for security and network cost purposes.

If you have applications that need the X-VCAP-REQUEST-ID HTTP header and can’t be upgraded, then you can use Istio to add it to requests and responses to mimic CLoud Foundry’s gorouter.

To mimic this header, we can create an EnvoyFilter that does the following:

  1. Watches for HTTP traffic coming into the gateway (make sure you target the same ingress gateway Kf is using).
  2. Saves Envoy’s built-in request ID.
  3. Copies that ID to the request.
  4. Mutates the response with the same request ID.

You may need to make changes to this filter if:

  • You rely on the HTTP/1.1 Upgrade header.
  • You need these headers for mesh (East-West) traffic.
  • You only want to target a subset of applications.

Example

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: vcap-http-header
  # Set the namespace to match the gateway.
  namespace: asm-gateways
spec:
  # Set the workload selector to match the Istio ingress gateway
  # your domain targets and/or your workload
  workloadSelector:
    labels:
      istio: ingressgateway
  configPatches:
  - applyTo: HTTP_FILTER
    match:
      context: GATEWAY
      listener:
        filterChain:
          filter:
            name: "envoy.filters.network.http_connection_manager"
            subFilter:
              name: "envoy.filters.http.router"
    patch:
      operation: INSERT_BEFORE
      value:
       name: envoy.lua
       typed_config:
         "@type": "type.googleapis.com/envoy.extensions.filters.http.lua.v3.Lua"
         inlineCode: |
          function envoy_on_request(request)
             local metadata = request:streamInfo():dynamicMetadata()
             -- Get Envoy's internal request ID
             local request_id = request:headers():get("x-request-id")

             if request_id ~= nil then
               -- Save the request ID for later and set it on the request
               -- for the application to conusme.
               metadata:set("envoy.filters.http.lua", "req.x-request-id", request_id)
               request:headers():add("x-vcap-request-id", request_id)
             end
           end

           function envoy_on_response(response)
             local metadata = response:streamInfo():dynamicMetadata():get("envoy.filters.http.lua")
             local request_id = metadata["req.x-request-id"]

             -- Set the value on the outbound response as well.
             if request_id ~= nil then
               response:headers():add("x-vcap-request-id", request_id)
             end
           end
Last modified November 18, 2024: Set version of php-buildpack to v4.6.23 to address git clone error in run-lifecycle task (#1081) (2ec6ee4)