Add priority option for repo configuration

pkg/api/bazeldnf/repo.go

@@ -12,4 +12,5 @@ type Repository struct {
 	Arch     string   `json:"arch"`
 	Mirrors  []string `json:"mirrors,omitempty"`
 	GPGKey   string   `json:"gpgkey,omitempty"`
+	Priority int      `json:"priority,omitempty"`
 }

pkg/reducer/reducer.go

@@ -102,11 +102,16 @@ func (r *RepoReducer) Resolve(packages []string) (matched []string, involved []*
 		if !found {
 			return nil, nil, fmt.Errorf("Package %s does not exist", req)
 		}
-		for i, p := range candidates {
-			discovered[p.String()] = candidates[i]
-		}
 
 		if len(candidates) > 0 {
+			selected := candidates[0]
+			for _, p := range candidates {
+				if selected.Repository.Priority > p.Repository.Priority {
+					selected = p
+				}
+			}
+
+			discovered[selected.String()] = selected
 			matched = append(matched, candidates[0].Name)
 		}
 	}