fix(examples): convert httpserver to Listeners

move to the activation.Listeners API and cleanup the README

Author: Brandon Philips

examples/activation/httpserver/README.md

@@ -1 +1,19 @@
-Example of using socket activation with systemd to serve a simple HTTP server on http://127.0.0.1:8076
+## socket activated http server
+
+This is a simple example of using socket activation with systemd to serve a
+simple HTTP server on http://127.0.0.1:8076
+
+To try it out `go get` the httpserver and run it under the systemd-activate helper
+
+```
+export GOPATH=`pwd`
+go get github.com/coreos/go-systemd/examples/activation/httpserver
+sudo /usr/lib/systemd/systemd-activate -l 127.0.0.1:8076 ./bin/httpserver
+```
+
+Then curl the URL and you will notice that it starts up:
+
+```
+curl 127.0.0.1:8076
+hello socket activated world!
+```

examples/activation/httpserver/httpserver.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"io"
-	"net"
 	"net/http"
 
 	"github.com/coreos/go-systemd/activation"
@@ -13,17 +12,15 @@ func HelloServer(w http.ResponseWriter, req *http.Request) {
 }
 
 func main() {
-	files := activation.Files(true)
-
-	if len(files) != 1 {
-		panic("Unexpected number of socket activation fds")
-	}
-
-	l, err := net.FileListener(files[0])
+	listeners, err := activation.Listeners(true)
 	if err != nil {
 		panic(err)
 	}
 
+	if len(listeners) != 1 {
+		panic("Unexpected number of socket activation fds")
+	}
+
 	http.HandleFunc("/", HelloServer)
-	http.Serve(l, nil)
+	http.Serve(listeners[0], nil)
 }