client.networks.containers() is always empty

[neilconway]

>>> import docker
>>> d = docker.from_env()
>>> [n.name for n in d.networks.list()]
['pedlintegrationtests_default', 'bridge', 'host', 'none']
>>> [n.containers for n in d.networks.list()]
[[], [], [], []]

$ docker network inspect pedlintegrationtests_default | jq '.[0].Containers | length'
4

$ pip freeze | grep docker && python --version && docker version
docker==2.5.1
docker-compose==1.16.1
docker-pycreds==0.2.1
dockerpty==0.4.1
nvidia-docker-compose==0.1.4
Python 3.5.2
Client:
 Version:      17.09.0-ce
 API version:  1.32
 Go version:   go1.8.3
 Git commit:   afdb6d4
 Built:        Tue Sep 26 22:42:18 2017
 OS/Arch:      linux/amd64

Server:
 Version:      17.09.0-ce
 API version:  1.32 (minimum version 1.12)
 Go version:   go1.8.3
 Git commit:   afdb6d4
 Built:        Tue Sep 26 22:40:56 2017
 OS/Arch:      linux/amd64
 Experimental: false

[shin-]

Does it work if you call reload() on the Network object?

[neilconway]

@shin- Yep, seems like that works:

$ python
Python 3.5.2 (default, Nov 17 2016, 17:05:23)
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import docker
>>> d = docker.from_env()
>>> networks = d.networks.list()
>>> [n.name for n in networks]
['bridge', 'host', 'none', 'pedlintegrationtests_default']
>>> [n.containers for n in networks]
[[], [], [], []]
>>> target = networks[3]
>>> target.containers
[]
>>> target.reload()
>>> target.containers
[<Container: b82bb19d44>, <Container: a6256ad04f>]
>>> [c.id for c in target.containers]
['b82bb19d44f18577ff7629e2bf9f350f3c3c581640e2a238ae710d84cb51d2ca', 'a6256ad04ff04f2ae4ab7d5e67398824a1eb7eba7baf6622519049e67629545c']
>>>
$ docker network inspect pedlintegrationtests_default | jq '.[0].Containers | length'
2

[shin-]

Yeah, what is happening is that the list() method generates the network objects from the /networks endpoint, which isn't as exhaustive as the /networks/<id> endpoint, resulting in some fields not being populated until you call reload. Obviously there's a speed tradeoff here, but maybe we could add a greedy parameter to the list method to indicate whether we want to load the complete object or not.

[neilconway]

Right, makes sense. FWIW, the current behavior is very confusing, because silently returning [] makes it hard to distinguish this situation (incomplete object) from "complete object but network has no connected containers". e.g., if containers was None (or there was a containers() method that threw an exception in this situation), that would at least make it more obvious.

[terminalmage]

@shin- How does one perform the same reload when using the APIClient? I'm seeing something similar when running docker.client.APIClient.networks(). Each network's containers key is an empty dict.

[terminalmage]

@shin- It looks, like you said, that hitting the endpoint for a specific ID (via docker.client.APIClient.inspect_network()) will get you the details for the containers.

Just adding a friendly reminder here to give the APIClient a little love if/when this enhancement is implemented.

[ChrsMark]

Hey guys,

I could not reproduce this behavior though.

>>> import docker
>>> d = docker.from_env()
>>> [n.name for n in d.networks.list()]
[u'none', u'host', u'apptest_default', u'ansibleplayground_default', u'bridge']
>>> [n.containers for n in d.networks.list()]
[[], [], [], [], [<Container: 62d7e7819d>]]

pip freeze | grep docker && python --version && docker version

-e git+https://github.com/ChrsMark/docker-py.git@bb148380e1ea92e26c8e4dc783dd18b8a39506c0#egg=docker
docker-pycreds==0.2.1
Python 2.7.6
Client:
 Version:      17.03.1-ce
 API version:  1.27
 Go version:   go1.7.5
 Git commit:   c6d412e
 Built:        Mon Mar 27 17:10:36 2017
 OS/Arch:      linux/amd64

Server:
 Version:      17.03.1-ce
 API version:  1.27 (minimum version 1.12)
 Go version:   go1.7.5
 Git commit:   c6d412e
 Built:        Mon Mar 27 17:10:36 2017
 OS/Arch:      linux/amd64
 Experimental: false