output-ws (#1136)

* add websocket output

* add tests

* update mod

output_ws_test.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"github.com/gorilla/websocket"
+	"log"
+	"net/http"
+	"sync"
+	"testing"
+)
+
+func TestWebSocketOutput(t *testing.T) {
+	wg := new(sync.WaitGroup)
+
+	wsAddr := startWebsocket(func(data []byte) {
+		wg.Done()
+	})
+	input := NewTestInput()
+	output := NewWebSocketOutput(wsAddr, &WebSocketOutputConfig{Workers: 1})
+
+	plugins := &InOutPlugins{
+		Inputs:  []PluginReader{input},
+		Outputs: []PluginWriter{output},
+	}
+
+	emitter := NewEmitter()
+	go emitter.Start(plugins, Settings.Middleware)
+
+	for i := 0; i < 10; i++ {
+		wg.Add(1)
+		input.EmitGET()
+	}
+
+	wg.Wait()
+	emitter.Close()
+}
+
+func startWebsocket(cb func([]byte)) string {
+	upgrader := websocket.Upgrader{}
+
+	http.HandleFunc("/test", func(w http.ResponseWriter, r *http.Request) {
+		c, err := upgrader.Upgrade(w, r, nil)
+		if err != nil {
+			log.Print("upgrade:", err)
+			return
+		}
+
+		go func(conn *websocket.Conn) {
+			defer conn.Close()
+			for {
+				_, msg, _ := conn.ReadMessage()
+				cb(msg)
+			}
+		}(c)
+	})
+
+	go func() {
+		err := http.ListenAndServe("localhost:8081", nil)
+		if err != nil {
+			log.Fatal("Can't start:", err)
+		}
+	}()
+
+	return "ws://localhost:8081/test"
+}