Go helloweb

Simple helloweb in Go that does the same as Python and Ruby versions.

/cc @gabriel, @Camata

README.rst

@@ -11,5 +11,6 @@ The following languages are demonstrated:
 
 - Python
 - Ruby
+- Go
 
 .. _helloworld: https://lab.nexedi.com/nexedi/slapos/tree/master/software/helloworld

go/.gitignore

+/helloweb

go/helloweb.go

+// helloweb is a simple web-server that says "Hello World" for every path
+//
+// helloweb [--logfile <logfile>] <bind-ip> <bind-port> ...
+package main
+
+import (
+    "os"
+    "fmt"
+    "time"
+    "log"
+    "flag"
+    "strings"
+    "net"
+    "net/http"
+)
+
+
+func asctime() string {
+    return time.Now().Format(time.ANSIC)
+}
+
+
+// wrapper for http.Handler to log all requests
+func logit(handler http.Handler) http.Handler {
+    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+        log.Printf("%s %s %s", r.RemoteAddr, r.Method, r.URL)
+        handler.ServeHTTP(w, r)
+    })
+}
+
+
+
+var name string
+
+func webhello(w http.ResponseWriter, r *http.Request) {
+    fmt.Fprintf(w, "Hello %s at `%s`  ; %s  (go)", name,
+                    r.URL.Path, asctime())
+}
+
+func main() {
+    logfile := flag.String("logfile", "", "log output to file instead of stderr")
+    flag.Usage = func() {
+        fmt.Println("Usage: helloweb.go [options] bind_ip bind_port ...")
+        flag.PrintDefaults()
+    }
+    flag.Parse()
+
+    if flag.NArg() < 2 {
+        flag.Usage()
+        os.Exit(1)
+    }
+
+    bind_ip    := flag.Arg(0)
+    bind_port  := flag.Arg(1)
+    bind_addr  := net.JoinHostPort(bind_ip, bind_port)
+
+    name = strings.Join(flag.Args()[2:], " ")
+    if name == "" {
+        name = "world"
+    }
+
+    // redirect log to file, if requested
+    if *logfile != "" {
+        f, err := os.OpenFile(*logfile, os.O_RDWR | os.O_CREATE | os.O_APPEND, 0644)
+        if err != nil {
+            panic(err)
+        }
+        defer f.Close()
+        log.SetOutput(f)
+    }
+
+    log.Printf("* %s helloweb.go starting at %s", asctime(), bind_addr)
+
+    http.HandleFunc("/", webhello)
+    log.Fatal(
+        http.ListenAndServe(bind_addr, logit(http.DefaultServeMux)))
+}