default tag to 'latest'

cmd/check/main.go

@@ -31,7 +31,7 @@ func main() {
 		return
 	}
 
-	ref := req.Source.Repository + ":" + req.Source.Tag
+	ref := req.Source.Repository + ":" + req.Source.Tag()
 
 	n, err := name.ParseReference(ref, name.WeakValidation)
 	if err != nil {

types.go

@@ -1,12 +1,22 @@
 package resource
 
+const DefaultTag = "latest"
+
 type Source struct {
 	Repository string `json:"repository"`
-	Tag        string `json:"tag"`
+	RawTag     string `json:"tag"`
 
 	Debug bool `json:"debug"`
 }
 
+func (s Source) Tag() string {
+	if s.RawTag == "" {
+		return DefaultTag
+	}
+
+	return s.RawTag
+}
+
 type Version struct {
 	Digest string `json:"digest"`
 }