EnvoyFilter for auth and header to metadata for rate limit override

envoyfilterauth.yml

---

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: core-authz-filter
spec:
  workloadSelector:
    labels:
      app: python-api
  configPatches:
    - applyTo: HTTP_FILTER
      match:
        context: SIDECAR_INBOUND
        listener:
          filterChain:
            filter:
              name: "envoy.filters.network.http_connection_manager"
              subFilter:
                # name: "envoy.router"
                name: envoy.filters.http.router
      patch:
        operation: INSERT_BEFORE
        value:
          name: envoy.ext_authz
          # connect_timeout: 1.0s
          typed_config:
            "@type": type.googleapis.com/envoy.extensions.filters.http.ext_authz.v3.ExtAuthz            
            grpc_service:
              envoy_grpc:
                cluster_name: external.authz.mystuff.svc.cluster.local
              timeout: 1.0s
            transport_api_version: V3
    - applyTo: HTTP_FILTER
      match:
        context: SIDECAR_INBOUND
        listener:
          filterChain:
            filter:
              name: "envoy.filters.network.http_connection_manager"
              subFilter:
                name: envoy.ext_authz
      patch:
        operation: INSERT_AFTER
        value:
          name: envoy.filters.http.header_to_metadata
          typed_config: 
            "@type": type.googleapis.com/envoy.extensions.filters.http.header_to_metadata.v3.Config
            request_rules:
              - header: x-ext-auth-ratelimit
                on_header_present:
                  key: rate.requests_per_unit
                  type: NUMBER
                on_header_missing:
                  key: rate.requests_per_unit
                  value: "1"
                  type: STRING
                remove: false
              - header: x-ext-auth-ratelimit-unit
                on_header_present:
                  key: rate.unit
                  type: STRING
                on_header_missing:
                  key: rate.unit
                  value: 'HOUR'
                  type: STRING
                remove: false
    - applyTo: HTTP_FILTER
      match:
        context: SIDECAR_INBOUND
        listener:
          filterChain:
            filter:
              name: "envoy.filters.network.http_connection_manager"
              subFilter:
                name: "envoy.filters.http.header_to_metadata"
      patch:
        operation: INSERT_AFTER
        value:
          name: envoy.filters.http.lua
          typed_config:
            "@type": type.googleapis.com/envoy.extensions.filters.http.lua.v3.Lua
            inline_code: |

              function PrintTable(tbl, depth, n)
                n = n or 0;
                depth = depth or 5;

                if (depth == 0) then
                    print(string.rep(' ', n).."...");
                    return;
                end

                if (n == 0) then
                    print(" ");
                end

                for key, value in pairs(tbl) do
                    if (key and type(key) == "number" or type(key) == "string") then
                        key = string.format("[\"%s\"]", key);

                        if (type(value) == "table") then
                            if (next(value)) then
                                print(string.rep(' ', n)..key.." = {");
                                PrintTable(value, depth - 1, n + 4);
                                print(string.rep(' ', n).."},");
                            else
                                print(string.rep(' ', n)..key.." = {},");
                            end
                        else
                            if (type(value) == "string") then
                                value = string.format("\"%s\"", value);
                            else
                                value = tostring(value);
                            end

                            print(string.rep(' ', n)..key.." = "..value..",");
                        end
                    end
                end

                if (n == 0) then
                    print(" ");
                end
              end

              function envoy_on_request(request_handle)

                  local reqs_per_unit = request_handle:streamInfo():dynamicMetadata():get("envoy.filters.http.header_to_metadata")["rate.requests_per_unit"]
                  local reqs_unit = request_handle:streamInfo():dynamicMetadata():get("envoy.filters.http.header_to_metadata")["rate.unit"]
                  request_handle:logWarn("requests_per_unit value: " .. reqs_per_unit)
                  request_handle:logWarn("unit value: " .. reqs_unit) 

                  local rate_limits = { requests_per_unit = reqs_per_unit, unit = reqs_unit}

                  request_handle:streamInfo():dynamicMetadata():set("envoy.filters.http.ratelimit.override", "limit", rate_limits)

                  local all_of_it = request_handle:streamInfo():dynamicMetadata()

                  request_handle:logWarn("DATA IN METADATA")
                  PrintTable(all_of_it)

              end