Since we now have several exceptions to the assumption that the
result of the pull would be on the last status line returned by
docker-py's pull(), I've changed the function so that it looks
through the status lines and returns what if finds on it.
Despite the repeated `break`s, the code seems simpler and a little
more coherent like this. From what I've checked using
`https://github.com/jlafon/ansible-profile`, the execution time is
mostly the same.
When pulling an image using Docker 1.8, it seems the output
JSON stream has an empty dict at the very end. This causes
ansible to fail when pulling an image, as it's expecting a
status message in that dict which it uses to determine whether
it had to download the image or not. As a bit of an ugly hack
for that which remains backward compatible, try the last item
in the stream, and if it's an empty dict, take the last-but-one
item instead.
The strip() is needed as the exact value appears to be '{}/r/n';
we could just match that, but it seems like the kind of thing
where maybe it'd happen to just be '{}/n' or '{}' or something
in some cases, so let's just use strip() in case.
A recent change [1] in docker between v1.8.2 and v1.8.3 changed what
is returned in the json when inspecting an image. Five variables which
could have been expected before will now be omited when empty. Only
one of those variables is being addressed in the docker, ExposedPorts.
Unfortunately there was also no API version change on this so this
can't be easily corrected with pinning the API to the older version.
This does a get() which will return None if the variable is not in the
dict formed from the json that was returned. Everything else works the
same way.
[1] 9098628b29
Before this patch:
- Command was matched if 'Command' field of docker-py
representation of Docker container ends with 'command' passed
to Ansible docker module by user.
- That can give false positives and false negatives.
- For example:
a) If 'command' was set up with more than one spaces,
like 'command=sleep 123', it would be never matched again
with a container(s) launched by this task.
Because after launching, command would be normalized and
appear, in docker-py API call, just as 'sleep 123' - with one
space. This is false negative case.
b) If 'entrypoint + command = command', for example
'sleep + 123 = sleep 123', module would give false positive
match.
This patch fixes it, by making matching more explicit - against
'Config'->Cmd' field of 'docker inspect' output, provided by docker-py
API and with proper normalization of user input by splitting it to
tokens with 'shlex.split()'.
