feat: remove preheat tag validate with required (#1363)

Signed-off-by: Gaius <gaius.qi@gmail.com>

internal/job/types.go

@@ -18,7 +18,7 @@ package job
 
 type PreheatRequest struct {
 	URL     string            `json:"url" validate:"required,url"`
-	Tag     string            `json:"tag" validate:"required"`
+	Tag     string            `json:"tag" validate:"omitempty"`
 	Digest  string            `json:"digest" validate:"omitempty"`
 	Filter  string            `json:"filter" validate:"omitempty"`
 	Headers map[string]string `json:"headers" validate:"omitempty"`

manager/job/preheat.go

@@ -47,11 +47,15 @@ var tracer = otel.Tracer("manager")
 type PreheatType string
 
 const (
+	// PreheatImageType is image type of preheat job.
 	PreheatImageType PreheatType = "image"
+
+	// PreheatFileType is file type of preheat job.
 	PreheatFileType PreheatType = "file"
 )
 
 const (
+	// Timeout is the default timeout of http client.
 	timeout = 1 * time.Minute
 )