Rendering: Check timeout error when the request failed (#57654)

* Check timeout error when the request failed

* Update error and check

* Uses errors.As to fix the lint

pkg/services/rendering/http_mode.go

@@ -137,8 +137,8 @@ func (rs *RenderingService) renderCSVViaHTTP(ctx context.Context, renderKey stri
 	return &RenderCSVResult{FilePath: filePath, FileName: downloadFileName}, nil
 }
 
-func (rs *RenderingService) doRequest(ctx context.Context, url *url.URL, headers map[string][]string) (*http.Response, error) {
-	req, err := http.NewRequestWithContext(ctx, "GET", url.String(), nil)
+func (rs *RenderingService) doRequest(ctx context.Context, u *url.URL, headers map[string][]string) (*http.Response, error) {
+	req, err := http.NewRequestWithContext(ctx, "GET", u.String(), nil)
 	if err != nil {
 		return nil, err
 	}
@@ -149,12 +149,18 @@ func (rs *RenderingService) doRequest(ctx context.Context, url *url.URL, headers
 		req.Header[k] = v
 	}
 
-	rs.log.Debug("calling remote rendering service", "url", url)
+	rs.log.Debug("calling remote rendering service", "url", u)
 
 	// make request to renderer server
 	resp, err := netClient.Do(req)
 	if err != nil {
 		rs.log.Error("Failed to send request to remote rendering service", "error", err)
+		var urlErr *url.Error
+		if errors.As(err, &urlErr) {
+			if urlErr.Timeout() {
+				return nil, ErrServerTimeout
+			}
+		}
 		return nil, fmt.Errorf("failed to send request to remote rendering service: %w", err)
 	}
 

pkg/services/rendering/interface.go

@@ -7,11 +7,13 @@ import (
 
 	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/services/org"
+	"github.com/grafana/grafana/pkg/util/errutil"
 )
 
 var ErrTimeout = errors.New("timeout error - you can set timeout in seconds with &timeout url parameter")
 var ErrConcurrentLimitReached = errors.New("rendering concurrent limit reached")
 var ErrRenderUnavailable = errors.New("rendering plugin not available")
+var ErrServerTimeout = errutil.NewBase(errutil.StatusUnknown, "rendering.serverTimeout", errutil.WithPublicMessage("error trying to connect to image-renderer service"))
 
 type RenderType string