pkg/util: Check errors (#19832)

* pkg/util: Check errors
* pkg/services: DRY up code

pkg/components/imguploader/azureblobuploader.go

@@ -51,7 +51,12 @@ func (az *AzureBlobUploader) Upload(ctx context.Context, imageDiskPath string) (
 	}
 	defer file.Close()
 
-	randomFileName := util.GetRandomString(30) + ".png"
+	randomFileName, err := util.GetRandomString(30)
+	if err != nil {
+		return "", err
+	}
+
+	randomFileName += pngExt
 	// upload image
 	az.log.Debug("Uploading image to azure_blob", "container_name", az.container_name, "blob_name", randomFileName)
 	resp, err := blob.FileUpload(az.container_name, randomFileName, file)

pkg/components/imguploader/gcsuploader.go

@@ -35,7 +35,12 @@ func NewGCSUploader(keyFile, bucket, path string) *GCSUploader {
 }
 
 func (u *GCSUploader) Upload(ctx context.Context, imageDiskPath string) (string, error) {
-	fileName := util.GetRandomString(20) + ".png"
+	fileName, err := util.GetRandomString(20)
+	if err != nil {
+		return "", err
+	}
+
+	fileName += pngExt
 	key := path.Join(u.path, fileName)
 
 	u.log.Debug("Opening key file ", u.keyFile)

pkg/components/imguploader/imguploader.go

@@ -9,6 +9,8 @@ import (
 	"github.com/grafana/grafana/pkg/setting"
 )
 
+const pngExt = ".png"
+
 type ImageUploader interface {
 	Upload(ctx context.Context, path string) (string, error)
 }

pkg/components/imguploader/s3uploader.go

@@ -61,7 +61,11 @@ func (u *S3Uploader) Upload(ctx context.Context, imageDiskPath string) (string,
 	}
 
 	s3_endpoint, _ := endpoints.DefaultResolver().EndpointFor("s3", u.region)
-	key := u.path + util.GetRandomString(20) + ".png"
+	rand, err := util.GetRandomString(20)
+	if err != nil {
+		return "", err
+	}
+	key := u.path + rand + pngExt
 	image_url := s3_endpoint.URL + "/" + u.bucket + "/" + key
 	log.Debug("Uploading image to s3. url = %s", image_url)
 

pkg/components/imguploader/webdavuploader.go

@@ -47,7 +47,12 @@ func (u *WebdavUploader) PublicURL(filename string) string {
 
 func (u *WebdavUploader) Upload(ctx context.Context, pa string) (string, error) {
 	url, _ := url.Parse(u.url)
-	filename := util.GetRandomString(20) + ".png"
+	filename, err := util.GetRandomString(20)
+	if err != nil {
+		return "", err
+	}
+
+	filename += pngExt
 	url.Path = path.Join(url.Path, filename)
 
 	imgData, err := ioutil.ReadFile(pa)