| 2017-06-16 07:08:28 |
Mark Kirkwood |
description |
This analysis was performed on Swift 2.7.0.
Suppose a container is quarantined. One of the fist things you want to do is check where it came from initially. So reach for swift-container-info. It turns out this is a bad idea:
$ cd /srv/node/vdc/quarantined/containers/3a7b4bae41a17d0f54b247c727b4f0cd/
$ ls -l
total 20
-rw------- 1 swift swift 18432 Aug 15 2016 3a7b4bae41a17d0f54b247c727b4f0cd.db
$ sudo swift-container-info ./3a7b4bae41a17d0f54b247c727b4f0cd.db
Traceback (most recent call last):
File "/usr/bin/swift-container-info", line 32, in <module>
print_info('container', *args, **vars(options))
File "/usr/lib/python2.7/dist-packages/swift/cli/info.py", line 327, in print_info
info = broker.get_info()
File "/usr/lib/python2.7/dist-packages/swift/container/backend.py", line 501, in get_info
with self.get() as conn:
File "/usr/lib/python2.7/contextlib.py", line 17, in __enter__
return self.gen.next()
File "/usr/lib/python2.7/dist-packages/swift/common/db.py", line 366, in get
self.possibly_quarantine(*sys.exc_info())
File "/usr/lib/python2.7/dist-packages/swift/common/db.py", line 347, in possibly_quarantine
renamer(self.db_dir, quar_path, fsync=False)
File "/usr/lib/python2.7/dist-packages/swift/common/utils.py", line 1094, in renamer
os.rename(old, new)
OSError: [Errno 16] Device or resource busy
ok that was bad - not only do we not get any useful info but it has tried to re-quarantine the container (and in the process mv the directory I am in...yikes, and hence the error):
$ ls -l
total 20
-rw------- 1 swift swift 18432 Aug 15 2016 3a7b4bae41a17d0f54b247c727b4f0cd.db
drwxr-xr-x 3 root root 24 Jun 16 06:55 quarantined
This comes about because swift-container-info:
- calls print_info which creates a ContainerBroker and...
- calls ContainerBroker.get_info using a self.get which resolves to DatabaseBroker.get
- DatabaseBroker.get calls self.possibly_quarantine
So the innocuous 'get_info' has dramatic side effects (possibly_quarantine)
We probably need to amend get_info e.g get_info(no_quarantine) to be side effect free for this type of use! |
This analysis was performed on Swift 2.7.0.
Suppose a container is quarantined. One of the fist things you want to do is check where it came from initially. So reach for swift-container-info. It turns out this is a bad idea:
$ cd /srv/node/vdc/quarantined/containers/3a7b4bae41a17d0f54b247c727b4f0cd/
$ ls -l
total 20
-rw------- 1 swift swift 18432 Aug 15 2016 3a7b4bae41a17d0f54b247c727b4f0cd.db
$ sudo swift-container-info ./3a7b4bae41a17d0f54b247c727b4f0cd.db
Traceback (most recent call last):
File "/usr/bin/swift-container-info", line 32, in <module>
print_info('container', *args, **vars(options))
File "/usr/lib/python2.7/dist-packages/swift/cli/info.py", line 327, in print_info
info = broker.get_info()
File "/usr/lib/python2.7/dist-packages/swift/container/backend.py", line 501, in get_info
with self.get() as conn:
File "/usr/lib/python2.7/contextlib.py", line 17, in __enter__
return self.gen.next()
File "/usr/lib/python2.7/dist-packages/swift/common/db.py", line 366, in get
self.possibly_quarantine(*sys.exc_info())
File "/usr/lib/python2.7/dist-packages/swift/common/db.py", line 347, in possibly_quarantine
renamer(self.db_dir, quar_path, fsync=False)
File "/usr/lib/python2.7/dist-packages/swift/common/utils.py", line 1094, in renamer
os.rename(old, new)
OSError: [Errno 16] Device or resource busy
ok that was bad - not only do we not get any useful info but it has tried to re-quarantine the container (and in the process mv the directory I am in...yikes, and hence the error):
$ ls -l
total 20
-rw------- 1 swift swift 18432 Aug 15 2016 3a7b4bae41a17d0f54b247c727b4f0cd.db
drwxr-xr-x 3 root root 24 Jun 16 06:55 quarantined
This comes about because swift-container-info:
- calls print_info which creates a ContainerBroker and...
- calls ContainerBroker.get_info which uses a self.get which resolves to DatabaseBroker.get
- DatabaseBroker.get calls self.possibly_quarantine
So the innocuous 'get_info' has dramatic side effects (possibly_quarantine)
We probably need to amend get_info e.g get_info(no_quarantine) to be side effect free for this type of use! |
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