envoy-filter.yaml

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: sample-lua
  namespace: default
spec:
  workloadSelector:
    labels:
      app: sample-app
  configPatches:
    - applyTo: HTTP_FILTER
      match:
        context: SIDECAR_INBOUND
        listener:
          filterChain:
            filter:
              name: "envoy.http_connection_manager"
              subFilter:
                name: "envoy.router"
      patch:
        operation: INSERT_BEFORE
        value:
          name: envoy.lua
          config:
            inlineCode: |
              function envoy_on_request(request_handle)
                    request_handle:headers():add("foo", "bar")
              end

              function envoy_on_response(response_handle)
                    response_handle:headers():add("foo", "bar")
              end