nested-builds-2.patch

gistfile1.diff

diff --git a/builder/dispatchers.go b/builder/dispatchers.go
index 541a300..b2a2675 100644
--- a/builder/dispatchers.go
+++ b/builder/dispatchers.go
@@ -357,12 +357,17 @@ func build(b *Builder, args []string, attributes map[string]bool) error {
 
 	contextPath = filepath.Join(c.RootfsPath(), contextPath)
 
-	if _, err := os.Stat(contextPath); os.IsNotExist(err) {
-		return fmt.Errorf("no such directory: %s", contextPath)
+	dirInfo, err := os.Stat(contextPath)
+	if err != nil {
+		return err
+	}
+	if !dirInfo.IsDir() {
+		return fmt.Errorf("%s is not a directory", contextPath)
 	}
 
 	if len(dockerfile) > 1 {
-		f, err := os.Create(filepath.Join(contextPath, "Dockerfile"))
+		dockerfilePath := filepath.Join(contextPath, "Dockerfile")
+		f, err := os.Create(dockerfilePath)
 		if err != nil {
 			return err
 		}
@@ -371,6 +376,17 @@ func build(b *Builder, args []string, attributes map[string]bool) error {
 		if err != nil {
 			return err
 		}
+
+		// Reset the modified times so the Dockerfile can't invalidate cache.
+		err = os.Chtimes(dockerfilePath, dirInfo.ModTime(), dirInfo.ModTime())
+		if err != nil {
+			return err
+		}
+		err = os.Chtimes(contextPath, dirInfo.ModTime(), dirInfo.ModTime())
+		if err != nil {
+			return err
+		}
+
 	}
 
 	archive, err := archive.Tar(contextPath, archive.Uncompressed)
@@ -380,15 +396,15 @@ func build(b *Builder, args []string, attributes map[string]bool) error {
 	defer archive.Close()
 
 	copy := *b
-	builder := &copy
+	newBuilder := &copy
 
-	_, err = builder.Run(archive)
+	_, err = newBuilder.Run(archive)
 	if err != nil {
 		return err
 	}
 
 	if b.RepoName != "" {
-		b.RepoName += "-builder"
+		b.RepoName = newBuilder.RepoName + "-builder"
 	}
 
 	return nil