Merge lp:~danilo/charms/trusty/glance-simplestreams-sync/next-lock-fix into lp:~openstack-charmers/charms/trusty/glance-simplestreams-sync/next

[Данило Шеган]

Only remove the lock file on exit if it was acquired in the first place. Stop it from hitting races and downloading same images multiple times.

See bug for details. Without this fix, the log had things like:

  http://paste.ubuntu.com/15789872/

which resulted in 2 xenial images and 1 trusty image.

With the fix, the result is a more reasonable

  http://paste.ubuntu.com/15789914/

[Данило Шеган (danilo)]

We've started off with next charm, and this issue does not seem to affect trunk :/

What's the current situation with this charm? What is the latest and greatest to use? Landscape Autopilot is using it, and we do need some changes on top of it for now.

=== modified file 'scripts/glance-simplestreams-sync.py'
--- scripts/glance-simplestreams-sync.py	2015-09-08 16:25:57 +0000
+++ scripts/glance-simplestreams-sync.py	2016-04-12 14:17:41 +0000
@@ -366,11 +366,10 @@
 
     log.info("glance-simplestreams-sync started.")
 
-    atexit.register(cleanup)
-
     lockfile = open(SYNC_RUNNING_FLAG_FILE_NAME, 'w')
     try:
         fcntl.flock(lockfile, fcntl.LOCK_EX | fcntl.LOCK_NB)
+        atexit.register(cleanup)
     except IOError:
         log.info("{} is locked, exiting".format(SYNC_RUNNING_FLAG_FILE_NAME))
         sys.exit(0)