Minor cleanups to atomic_helper and add unit tests.

Change atomic_helper.write_file to have same same signature as write_file.
Add some simple unit tests for atomic_helper.

3 files changed, 21 insertions, 15 deletions

diff --git a/cloudinit/atomic_helper.py b/cloudinit/atomic_helper.py
index 15319f71..a3cfd942 100644
--- a/cloudinit/atomic_helper.py
+++ b/cloudinit/atomic_helper.py
@@ -5,21 +5,27 @@ import json
 import os
 import tempfile
 
+_DEF_PERMS = 0o644
 
-def atomic_write_file(path, content, mode='w'):
+
+def write_file(filename, content, mode=_DEF_PERMS, omode="wb"):
+    # open filename in mode 'omode', write content, set permissions to 'mode'
     tf = None
     try:
-        tf = tempfile.NamedTemporaryFile(dir=os.path.dirname(path),
-                                         delete=False, mode=mode)
+        tf = tempfile.NamedTemporaryFile(dir=os.path.dirname(filename),
+                                         delete=False, mode=omode)
         tf.write(content)
         tf.close()
-        os.rename(tf.name, path)
+        os.chmod(tf.name, mode)
+        os.rename(tf.name, filename)
     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")
+def write_json(filename, data, mode=_DEF_PERMS):
+    # dump json representation of data to file filename.
+    return write_file(
+        filename, json.dumps(data, indent=1, sort_keys=True) + "\n",
+        omode="w", mode=mode)
diff --git a/cloudinit/cmd/main.py b/cloudinit/cmd/main.py
index ba22b168..83eb02c9 100644
--- a/cloudinit/cmd/main.py
+++ b/cloudinit/cmd/main.py
@@ -46,7 +46,7 @@ from cloudinit.reporting import events
 from cloudinit.settings import (PER_INSTANCE, PER_ALWAYS, PER_ONCE,
                                 CLOUD_CONFIG)
 
-from cloudinit.atomic_helper import atomic_write_json
+from cloudinit import atomic_helper
 
 from cloudinit.dhclient_hook import LogDhclient
 
@@ -513,7 +513,7 @@ def status_wrapper(name, args, data_d=None, link_d=None):
     v1['stage'] = mode
     v1[mode]['start'] = time.time()
 
-    atomic_write_json(status_path, status)
+    atomic_helper.write_json(status_path, status)
     util.sym_link(os.path.relpath(status_path, link_d), status_link,
                   force=True)
 
@@ -536,7 +536,7 @@ def status_wrapper(name, args, data_d=None, link_d=None):
     v1[mode]['finished'] = time.time()
     v1['stage'] = None
 
-    atomic_write_json(status_path, status)
+    atomic_helper.write_json(status_path, status)
 
     if mode == "modules-final":
         # write the 'finished' file
@@ -545,9 +545,9 @@ def status_wrapper(name, args, data_d=None, link_d=None):
             if v1[m]['errors']:
                 errors.extend(v1[m].get('errors', []))
 
-        atomic_write_json(result_path,
-                          {'v1': {'datasource': v1['datasource'],
-                                  'errors': errors}})
+        atomic_helper.write_json(
+            result_path, {'v1': {'datasource': v1['datasource'],
+                          'errors': errors}})
         util.sym_link(os.path.relpath(result_path, link_d), result_link,
                       force=True)
 
diff --git a/cloudinit/dhclient_hook.py b/cloudinit/dhclient_hook.py
index 9dcbe39c..82cb1855 100644
--- a/cloudinit/dhclient_hook.py
+++ b/cloudinit/dhclient_hook.py
@@ -3,7 +3,7 @@
 
 import os
 
-from cloudinit.atomic_helper import atomic_write_json
+from cloudinit import atomic_helper
 from cloudinit import log as logging
 from cloudinit import stages
 
@@ -46,5 +46,5 @@ class LogDhclient(object):
         envs = os.environ
         if self.hook_file is None:
             return
-        atomic_write_json(self.hook_file, self.get_vals(envs))
+        atomic_helper.write_json(self.hook_file, self.get_vals(envs))
         LOG.debug("Wrote dhclient options in %s", self.hook_file)