Don't delete the image that we're currently running, for safety.

client/client.py

@@ -86,7 +86,7 @@ class Client(threadedclient.WebSocketClient):
       return int(float(fh.readline().split(' ', 1)[0]))
 
   def _NextTimestamp(self):
-    next_image = os.path.basename(os.readlink('/isodevice/iconograph/current'))
+    next_image = lib.GetCurrentImage()
     return int(next_image.split('.', 1)[0])
 
   def _OnImageTypes(self, data):
@@ -106,7 +106,7 @@ class Client(threadedclient.WebSocketClient):
         FLAGS.https_client_cert,
         FLAGS.https_client_key)
     fetch.Fetch()
-    fetch.DeleteOldImages()
+    fetch.DeleteOldImages(skip={'%d.iso' % self._config['timestamp']})
 
     update = update_grub.GrubUpdater(
         FLAGS.image_dir,

client/fetcher.py

@@ -166,9 +166,10 @@ class Fetcher(object):
     self._FetchImage(image)
     self._SetCurrent(image)
 
-  def DeleteOldImages(self, max_images=5):
+  def DeleteOldImages(self, max_images=5, skip=None):
     if not max_images:
       return
+    skip = skip or set()
     images = []
     for filename in os.listdir(self._image_dir):
       match = self._FILE_REGEX.match(filename)
@@ -177,6 +178,8 @@ class Fetcher(object):
       images.append((int(match.group('timestamp')), filename))
     images.sort(reverse=True)
     for timestamp, filename in images[max_images:]:
+      if filename in skip:
+        continue
       print('Deleting old image:', filename, flush=True)
       path = os.path.join(self._image_dir, filename)
       os.unlink(path)

client/lib.py

@@ -1,3 +1,4 @@
+import os
 import re
 import subprocess
 
@@ -13,3 +14,8 @@ def GetVolumeID(path):
   ])
   match = _VOLUME_ID_REGEX.search(isoinfo)
   return match.group('volume_id').decode('ascii')
+
+
+def GetCurrentImage(image_dir='/isodevice/iconograph'):
+  current_path = os.path.join(image_dir, 'current')
+  return os.path.basename(os.readlink(current_path))

client/update_grub.py

@@ -23,13 +23,13 @@ class GrubUpdater(object):
 
     with tempfile.NamedTemporaryFile('w', dir=grub_dir, delete=False) as fh:
       try:
-        current = os.readlink(os.path.join(self._image_dir, 'current'))
+        current = lib.GetCurrentImage(self._image_dir)
 
         fh.write("""
 set timeout=5
 set default=%(default_image_filename)s
 """ % {
-          'default_image_filename': os.path.basename(current),
+          'default_image_filename': current,
         })
 
         files = []