Add http_pingpong

http_pingpong.go

@@ -0,0 +1,71 @@
+package main
+
+import (
+	"flag"
+	"net/http"
+)
+
+// Author: Ceyhun Uzunoglu <ceyhunuzngl [AT] gmail {DOT} com>
+// Reverse proxy to expose internal service response
+
+// Example:
+//   Serve: go run http_pingpong.go -port ":17000" -endpoint "/metrics" -uri "http://localhost:8270/crabserver/metrics"
+//   Get:   curl http://IP:17000/metrics
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"os"
+)
+
+var (
+	listeningPort   = flag.String("port", ":17000", "port to expose metrics and web interface.")
+	metricsEndpoint = flag.String("endpoint", "/metrics", "Path under which to expose metrics.")
+	scrapeURI       = flag.String("uri", "", "URI of server status page we're going to scrape")
+	verbose         = flag.Bool("verbose", false, "verbose output")
+)
+
+func getResult(w http.ResponseWriter, _ *http.Request) {
+	resp, err := http.Get(*scrapeURI)
+	if *verbose {
+		log.SetFlags(log.LstdFlags | log.Lshortfile)
+	} else {
+		log.SetFlags(log.LstdFlags)
+	}
+	if err != nil {
+		log.Println(err)
+		w.WriteHeader(http.StatusNotFound)
+		return
+	}
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		log.Println(err)
+		w.WriteHeader(http.StatusNotFound)
+		return
+	}
+	w.WriteHeader(http.StatusOK)
+	_, err = io.WriteString(w, string(body))
+	if err != nil {
+		w.WriteHeader(http.StatusUnprocessableEntity)
+		return
+	}
+}
+
+func main() {
+	flag.Parse()
+	if *verbose {
+		log.SetFlags(log.LstdFlags | log.Lshortfile)
+	} else {
+		log.SetFlags(log.LstdFlags)
+	}
+	http.HandleFunc(*metricsEndpoint, getResult)
+	err := http.ListenAndServe(*listeningPort, nil)
+	if errors.Is(err, http.ErrServerClosed) {
+		fmt.Printf("server closed\n")
+	} else if err != nil {
+		fmt.Printf("error starting server: %s\n", err)
+		os.Exit(1)
+	}
+}