envoy-local-reply-not-working

readme.md

• curl -> envoy(8000) -> app.go (9000)
• envoy has local reply, when response is 400, change to 550
• config is from official sample
• responses are supposed to be rewriten as 550, but not happening.

go run app.go

# new terminal start envoy, using func-e, but should be the same.
# envoy listening on port 8000.
func-e run -c ./bootstrap.yaml --component-log-level "http:trace"

# curl envoy, which routes back to the app.
curl -Htest-header:exact-match-value localhost:8000/code/400 -v
*   Trying 127.0.0.1:8000...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 8000 (#0)
> GET /code/400 HTTP/1.1
> Host: localhost:8000
> User-Agent: curl/7.68.0
> Accept: */*
> test-header:exact-match-value
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 400 Bad Request
< date: Thu, 28 Apr 2022 20:22:09 GMT
< content-length: 0
< x-envoy-upstream-service-time: 0
< server: incfly-envoy
<

app.go

// +build ignore

package main

import (
	"flag"
	"fmt"
	"net"
	"net/http"
	"strconv"
	"strings"
	"time"
)

var (
	httpPort string
)

func init() {
	flag.StringVar(&httpPort, "http", "9000", "the http port to listen on")
}

func handleByCode(w http.ResponseWriter, r *http.Request) {
	o := strings.Split(r.URL.Path, "/")
	code := 503
	if len(o) >= 3 {
		c, err := strconv.Atoi(o[2])
		if err == nil {
			code = c
		}
	}
	fmt.Printf("handleByCode: %v\n", code)
	w.WriteHeader(code)
}

func handleHTTP(w http.ResponseWriter, r *http.Request) {
	fmt.Printf("[%v] request path: %v\n", time.Now(), r.URL.Path)
	if strings.HasPrefix(r.URL.Path, "/code/") {
		handleByCode(w, r)
		return
	}
}

func handleTCP(conn net.Conn) {
	// Make a buffer to hold incoming data.
	buf := make([]byte, 1024)
	// Read the incoming connection into the buffer.
	len, err := conn.Read(buf)
	if err != nil {
		fmt.Println("Error reading:", err.Error())
	}
	payload := string(buf[:len])
	fmt.Printf("received tcp conn\nremote address %v\nlocal address: %v\ndata\n%v",
		conn.RemoteAddr(), conn.LocalAddr(), string(payload))
	lines := strings.Split(payload, "\n")
	cmd := "reset"
	for _, i := range lines {
		if strings.Contains(i, "cmd") {
			cmd = strings.TrimSpace(strings.Split(i, " ")[1])
			break
		}
	}
	fmt.Printf("execute command:%v\n", cmd)
	switch cmd {
	case "hang":
		time.Sleep(3600 * time.Second)
		break
	default:
		conn.Close()
	}
}

func main() {
	flag.Parse()
	fmt.Printf("hello world, starting the server at port %v\n", httpPort)
	http.HandleFunc("/", handleHTTP)
	if err := http.ListenAndServe(fmt.Sprintf("localhost:%v", httpPort), nil); err != nil {
		panic(fmt.Sprintf("failed to listen http server: %v", err))
	}
}

bootstrap.yaml

static_resources:
  clusters:
  - name: app
    type: STATIC
    load_assignment:
      cluster_name: app
      endpoints:
      - lb_endpoints:
        - endpoint:
            address:
              socket_address:
                address: 127.0.0.1
                port_value: 9000
  listeners:
  - address:
      socket_address:
        address: 0.0.0.0
        port_value: 8000
    filter_chains:
    - filters:
      - name: envoy.filters.network.http_connection_manager
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
          codec_type: AUTO
          server_name: incfly-envoy
          local_reply_config:
            mappers:
            - filter:
                status_code_filter:
                  comparison:
                    op: EQ
                    value:
                      default_value: 400
                      runtime_key: key_b
              status_code: 550
            body_format:
              text_format_source:
                inline_string: "%RESPONSE_CODE% - %LOCAL_REPLY_BODY%"
          stat_prefix: ingress_http
          route_config:
            name: local_route
            virtual_hosts:
            - name: backend
              domains:
              - "*"
              routes:
              # no retry!
              - match:
                  prefix: "/"
                route:
                  cluster: app
          http_filters:
          - name: envoy.filters.http.router
admin:
  address:
    socket_address:
      address: 0.0.0.0
      port_value: 15001