Add support for UDP in kuryr/demo container

Update kuryr/demo container to support UDP server.
After this change, the kuryr/demo image runs both HTTP and UDP
servers.
The listeners ports values could be configured using pod's
environment variables.
And in addition, a simple udp client binary tool was added to
image, to use it, you should run :
udp_client <server's_ip> <server's port>

Change-Id: I9f2f2ad3273f947fecb776c0f56f6829df81aa67

test_container/Dockerfile.builder

@@ -156,6 +156,8 @@ RUN mkdir -p rootfs/usr/bin; \
 	cp /usr/local/bin/curl rootfs/usr/bin/curl
 
 ADD ./server.go .
+ADD ./udp_client.go .
 RUN go build -ldflags "-linkmode external -extldflags -static" -o rootfs/usr/bin/helloserver server.go
+RUN go build -ldflags "-linkmode external -extldflags -static" -o rootfs/usr/bin/udp_client  udp_client.go
 RUN mkdir -p rootfs/etc/ssl/certs \
 	&& cp /etc/ssl/certs/ca-certificates.crt rootfs/etc/ssl/certs/ca-certificates.crt

test_container/server.go

@@ -3,9 +3,13 @@ package main
 import (
 	"fmt"
 	"log"
+	"net"
 	"net/http"
 	"os"
+	"runtime"
+	"strconv"
 	"strings"
+	"sync"
 )
 
 func handler(w http.ResponseWriter, r *http.Request) {
@@ -16,22 +20,63 @@ func handler(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-func main() {
-	http.HandleFunc("/", handler)
+func send_udp_response(conn *net.UDPConn, addr *net.UDPAddr) {
+	hostname, err := os.Hostname()
+	if err == nil {
+		resp_str := fmt.Sprintf("%s: HELLO! I AM ALIVE!!!\n", hostname)
+		_, err := conn.WriteToUDP([]byte(resp_str), addr)
+		if err != nil {
+			log.Println("Failed to reply to client")
+		}
+	}
+}
 
+func run_udp_server(port int) {
+
+	p := make([]byte, 2048)
+
+	log.Println("Running UDP server")
+	ser, _ := net.ListenUDP("udp", &net.UDPAddr{IP: []byte{0, 0, 0, 0}, Port: port, Zone: ""})
+	defer ser.Close()
+
+	for {
+		_, remoteaddr, err := ser.ReadFromUDP(p)
+		if err != nil {
+			log.Println("We got an Error on reading")
+			continue
+		}
+		log.Println("Received UDP request")
+		send_udp_response(ser, remoteaddr)
+	}
+}
+
+func udp_handling(wg sync.WaitGroup) {
+	udpPort, udpPortPresent := os.LookupEnv("UDP_PORT")
+
+	var port_num int = 9090
+	if udpPortPresent {
+		port_num, _ = strconv.Atoi(strings.TrimSpace(udpPort))
+	}
+	run_udp_server(port_num)
+}
+
+func http_handling(wg sync.WaitGroup) {
+	defer wg.Done()
+
+	http.HandleFunc("/", handler)
 	httpsPort, httpsPortPresent := os.LookupEnv("HTTPS_PORT")
 
 	var port string
+
 	if httpsPortPresent {
 		port = ":" + strings.TrimSpace(httpsPort)
-
 		cert, certPresent := os.LookupEnv("HTTPS_CERT_PATH")
 		key, keyPresent := os.LookupEnv("HTTPS_KEY_PATH")
 
 		if !certPresent || !keyPresent {
 			log.Fatal("HTTPS_PORT configured but missing HTTPS_CERT_PATH and/or HTTPS_KEY_PATH")
 		}
-
+		log.Println("Running HTTPS server")
 		log.Fatal(http.ListenAndServeTLS(port, cert, key, nil))
 	} else {
 		httpPort, confPresent := os.LookupEnv("HTTP_PORT")
@@ -40,7 +85,20 @@ func main() {
 		} else {
 			port = ":8080"
 		}
-
+		log.Println("Running HTTP server")
 		log.Fatal(http.ListenAndServe(port, nil))
 	}
+	log.Println("Exit HTTP server...")
+
+}
+
+func main() {
+
+	runtime.GOMAXPROCS(2)
+	var wg sync.WaitGroup
+	wg.Add(2)
+
+	go http_handling(wg)
+	go udp_handling(wg)
+	wg.Wait()
 }

test_container/udp_client.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"net"
+	"os"
+)
+
+// udp_client.go syntax : udp_client <server_IP> <server_port>
+
+func main() {
+
+	server_ip_port := os.Args[1] + ":" + os.Args[2]
+
+	p := make([]byte, 2048)
+	conn, err := net.Dial("udp", server_ip_port)
+	if err != nil {
+		fmt.Printf("Some error %v", err)
+		return
+	}
+	fmt.Fprintf(conn, "Hi UDP Server, How are you?")
+	_, err = bufio.NewReader(conn).Read(p)
+	if err == nil {
+		fmt.Printf("%s\n", p)
+	} else {
+		fmt.Printf("Some error %v\n", err)
+	}
+	conn.Close()
+}