Add basic websocket structure and request upgrader

api/websocket.go

@@ -0,0 +1,46 @@
+package api
+
+import (
+	"errors"
+	"github.com/gorilla/websocket"
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/api/dto"
+	"gitlab.hpi.de/codeocean/codemoon/poseidon/runner"
+	"net/http"
+)
+
+var connUpgrade = websocket.Upgrader{
+	ReadBufferSize:  1024,
+	WriteBufferSize: 1024,
+}
+
+// connectToRunner is a placeholder for now and will become the endpoint for websocket connections.
+func connectToRunner(writer http.ResponseWriter, request *http.Request) {
+	r, ok := runner.FromContext(request.Context())
+	if !ok {
+		log.Error("Runner not set in request context.")
+		writeInternalServerError(writer, errors.New("findRunnerMiddleware failure"), dto.ErrorUnknown)
+		return
+	}
+	executionId := request.URL.Query().Get(ExecutionIdKey)
+	connClient, err := connUpgrade.Upgrade(writer, request, nil)
+	if err != nil {
+		writeInternalServerError(writer, err, dto.ErrorUnknown)
+		return
+	}
+	defer func(connClient *websocket.Conn) {
+		err := connClient.Close()
+		if err != nil {
+			writeInternalServerError(writer, err, dto.ErrorUnknown)
+		}
+	}(connClient)
+
+	// ToDo: Implement communication forwarding
+	err, ok = r.Execute(runner.ExecutionId(executionId))
+	if !ok {
+		writeBadRequest(writer, errors.New("invalid Execution Id"))
+		return
+	} else if err != nil {
+		writeInternalServerError(writer, err, dto.ErrorUnknown)
+		return
+	}
+}