refactory the code and add CreateTargetTarfile in fs_util.go

pkg/buildcontext/azureblob.go

@@ -54,18 +54,15 @@ func (b *AzureBlob) UnpackTarFromBuildContext() (string, error) {
 		return parts.Host, err
 	}
 
-	//Create directory and file for downloading context file
+	// Create directory and target file for downloading the context file
 	directory := constants.BuildContextDir
 	tarPath := filepath.Join(directory, constants.ContextTar)
-	if err := os.MkdirAll(directory, 0750); err != nil {
-		return directory, err
-	}
-	file, err := os.Create(tarPath)
+	file, err := util.CreateTargetTarfile(tarPath)
 	if err != nil {
-		return directory, err
+		return tarPath, err
 	}
 
-	//Downloading contextfile from Azure Blob Storage
+	// Downloading contextfile from Azure Blob Storage
 	p := azblob.NewPipeline(credential, azblob.PipelineOptions{})
 	blobURL := azblob.NewBlobURL(*u, p)
 	ctx := context.Background()

pkg/util/fs_util.go

@@ -640,3 +640,17 @@ func setFilePermissions(path string, mode os.FileMode, uid, gid int) error {
 	// Must chmod after chown because chown resets the file mode.
 	return os.Chmod(path, mode)
 }
+
+// CreateTargetTarfile creates target tar file for downloading the context file. 
+// Make directory if directory does not exist
+func CreateTargetTarfile(tarpath string) (*os.File, error) {
+	baseDir := filepath.Dir(tarpath)
+	if _, err := os.Lstat(baseDir); os.IsNotExist(err) {
+		logrus.Debugf("baseDir %s for file %s does not exist. Creating.", baseDir, tarpath)
+		if err := os.MkdirAll(baseDir, 0755); err != nil {
+			return nil, err
+		}
+	}
+	return os.Create(tarpath)
+
+}