cluster: add DirFS() using hackpadfs/os

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/cluster/cluster_fs.go

@@ -0,0 +1,25 @@
+package cluster
+
+import (
+	"io/fs"
+	"path/filepath"
+
+	"github.com/hack-pad/hackpadfs/os"
+)
+
+// DirFS returns a file system (an [fs.FS]) for the tree
+// of files rooted at the directory dir.
+func DirFS(dir string) (fs.FS, error) {
+	dir = filepath.Clean(dir)
+	fullPath, err := filepath.Abs(dir)
+	if err != nil {
+		return nil, err
+	}
+
+	sub, err := os.NewFS().Sub(fullPath[1:])
+	if err != nil {
+		return nil, err
+	}
+
+	return sub, nil
+}