lib/netext/httpext: set request context explicitly

Go 1.13 and below has a bug that client timeout will not be propagated
to http request context. That bug was fixed already and will be present
in go1.14 (golang/go#31657).

Currently, we set Timeout in our Client, but do not use it else where.
It will not affect the request context for now, but does when go1.14
release.

To make it compatible and works correctly with other go versions, we set
the request context explicitly with the timeout.

Update #1260

lib/netext/httpext/request.go

@@ -283,7 +283,6 @@ func MakeRequest(ctx context.Context, preq *ParsedHTTPRequest) (*Response, error
 	resp := &Response{ctx: ctx, URL: preq.URL.URL, Request: *respReq}
 	client := http.Client{
 		Transport: transport,
-		Timeout:   preq.Timeout,
 		CheckRedirect: func(req *http.Request, via []*http.Request) error {
 			resp.URL = req.URL.String()
 
@@ -312,7 +311,9 @@ func MakeRequest(ctx context.Context, preq *ParsedHTTPRequest) (*Response, error
 		},
 	}
 
-	mreq := preq.Req.WithContext(ctx)
+	reqCtx, cancelFunc := context.WithTimeout(ctx, preq.Timeout)
+	defer cancelFunc()
+	mreq := preq.Req.WithContext(reqCtx)
 	res, resErr := client.Do(mreq)
 
 	// TODO(imiric): It would be safer to check for a writeable
@@ -367,7 +368,7 @@ func MakeRequest(ctx context.Context, preq *ParsedHTTPRequest) (*Response, error
 	}
 
 	if resErr != nil {
-		// Do *not* log errors about the contex being cancelled.
+		// Do *not* log errors about the context being cancelled.
 		select {
 		case <-ctx.Done():
 		default:

lib/netext/httpext/request_test.go

@@ -98,13 +98,21 @@ func TestMakeRequestError(t *testing.T) {
 		defer srv.Close()
 		ctx, cancel := context.WithCancel(context.Background())
 		defer cancel()
+		logger := logrus.New()
+		logger.Level = logrus.DebugLevel
 		state := &lib.State{
 			Options:   lib.Options{RunTags: &stats.SampleTags{}},
 			Transport: srv.Client().Transport,
+			Logger:    logger,
 		}
 		ctx = lib.WithState(ctx, state)
 		req, _ := http.NewRequest("GET", srv.URL, nil)
-		var preq = &ParsedHTTPRequest{Req: req, URL: &URL{u: req.URL}, Body: new(bytes.Buffer)}
+		var preq = &ParsedHTTPRequest{
+			Req:     req,
+			URL:     &URL{u: req.URL},
+			Body:    new(bytes.Buffer),
+			Timeout: 10 * time.Second,
+		}
 
 		res, err := MakeRequest(ctx, preq)