1 files changed, 25 insertions, 0 deletions
diff --git a/cloudinit/atomic_helper.py b/cloudinit/atomic_helper.py
new file mode 100644
index 00000000..15319f71
--- /dev/null
+++ b/cloudinit/atomic_helper.py
@@ -0,0 +1,25 @@
+#!/usr/bin/python
+# vi: ts=4 expandtab
+
+import json
+import os
+import tempfile
+
+
+def atomic_write_file(path, content, mode='w'):
+    tf = None
+    try:
+        tf = tempfile.NamedTemporaryFile(dir=os.path.dirname(path),
+                                         delete=False, mode=mode)
+        tf.write(content)
+        tf.close()
+        os.rename(tf.name, path)
+    except Exception as e:
+        if tf is not None:
+            os.unlink(tf.name)
+        raise e
+
+
+def atomic_write_json(path, data):
+    return atomic_write_file(path, json.dumps(data, indent=1,
+                                              sort_keys=True) + "\n")