Adds a workload name header to outbound requests in istio

x-workload-name-envoyfilter.yaml

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: add-x-workload-header
  namespace: istio-system
  annotations:
    name: Add Workload Header
    description: Adds an x-workload-header
spec:
  configPatches:
    - applyTo: HTTP_FILTER
      match:
        context: SIDECAR_OUTBOUND
        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_handle)
                local function isempty(s)
                  return s == nil or s == ''
                end

                local request_headers = request_handle:headers()
                local workload_name = os.getenv("ISTIO_META_WORKLOAD_NAME")
                if isempty(workload_name) then
                  workload_name = os.getenv("CANONICAL_SERVICE")
                end
                if isempty(workload_name) then
                  workload_name = os.getenv("POD_NAMESPACE")
                end
                if not isempty(workload_name) then
                  request_handle:headers():replace("x-workload-name", workload_name)
                end
              end