Add directory check to ensure the directory exists

Signed-off-by: Vu Dinh <vdinh@redhat.com>

Author: dinhxuanvu

docs/design/operator-bundle.md

@@ -159,7 +159,7 @@ The `--package` or `-p` is the name of package fo the operator such as `etcd` wh
 
 All information in `annotations.yaml` is also existed in `LABEL` section of `Dockerfile`.
 
-The `Dockerfile` can used to manually build bundle image using container image tools such as Docker, Podman or Buildah. For example, the Docker build command would be:
+The `Dockerfile` can be used manually to build the bundle image using container image tools such as Docker, Podman or Buildah. For example, the Docker build command would be:
 
 ```bash
 $ docker build -f /path/to/Dockerfile -t quay.io/test/test-operator:latest /path/to/manifests/

pkg/lib/bundle/build.go

@@ -54,8 +54,13 @@ func ExecuteCommand(cmd *exec.Cmd) error {
 // @channelDefault: The default channel for the bundle image
 // @overwrite: Boolean flag to enable overwriting annotations.yaml locally if existed
 func BuildFunc(directory, imageTag, imageBuilder, packageName, channels, channelDefault string, overwrite bool) error {
+	_, err := os.Stat(directory)
+	if os.IsNotExist(err) {
+		return err
+	}
+
 	// Generate annotations.yaml and Dockerfile
-	err := GenerateFunc(directory, packageName, channels, channelDefault, overwrite)
+	err = GenerateFunc(directory, packageName, channels, channelDefault, overwrite)
 	if err != nil {
 		return err
 	}

pkg/lib/bundle/generate.go

@@ -43,7 +43,10 @@ type AnnotationMetadata struct {
 // @channelDefault: The default channel for the bundle image
 // @overwrite: Boolean flag to enable overwriting annotations.yaml locally if existed
 func GenerateFunc(directory, packageName, channels, channelDefault string, overwrite bool) error {
-	var mediaType string
+	_, err := os.Stat(directory)
+	if os.IsNotExist(err) {
+		return err
+	}
 
 	// Determine mediaType
 	mediaType, err := GetMediaType(directory)