Docker-py: Container.status returns 'created' for 'exited' container

[waynr]

pip freeze output:

appdirs==1.4.3
argh==0.26.2
click==6.7
coverage==4.1
discover==0.4.0
docker==2.1.0
docker-pycreds==0.2.1
extras==1.0.0
fixtures==3.0.0
flake8==3.3.0
-e git+http://github.com/waynr/jankman@ac6c6d26e88b424e92e328c4da4040f43a4e11e5#egg=jankman
-e git+http://github.com/openstack-infra/jenkins-job-builder@161473d1b731b0fd84abf99f8f158383d21c83a0#egg=jenkins_job_builder
Jinja2==2.9.5
linecache2==1.0.0
MarkupSafe==1.0
mccabe==0.6.1
multi-key-dict==2.0.3
nose==1.3.7
packaging==16.8
pathtools==0.1.2
pbr==2.0.0
pluggy==0.3.1
py==1.4.33
pycodestyle==2.3.1
pyflakes==1.5.0
pyparsing==2.2.0
python-jenkins==0.4.14
python-mimeparse==1.6.0
PyYAML==3.12
requests==2.13.0
six==1.10.0
stevedore==1.20.0
testtools==2.2.0
tox==2.3.1
traceback2==1.4.0
unittest2==1.1.0
virtualenv==15.1.0
watchdog==0.8.3
websocket-client==0.40.0

Python version

Python 3.5.2

docker version

Client:
 Version:      17.03.0-ce
 API version:  1.24 (downgraded from 1.26)
 Go version:   go1.7.5
 Git commit:   3a232c8
 Built:        Tue Feb 28 07:59:18 2017
 OS/Arch:      linux/amd64

Server:
 Version:      1.12.3
 API version:  1.24 (minimum version )
 Go version:   go1.6.3
 Git commit:   6b644ec
 Built:        
 OS/Arch:      linux/amd64
 Experimental: false

docker info

Containers: 26
 Running: 10
 Paused: 0
 Stopped: 16
Images: 27
Server Version: 1.12.3
Storage Driver: devicemapper
 Pool Name: docker-253:2-67128345-pool
 Pool Blocksize: 65.54 kB
 Base Device Size: 10.74 GB
 Backing Filesystem: xfs
 Data file: /dev/loop0
 Metadata file: /dev/loop1
 Data Space Used: 40.55 GB
 Data Space Total: 107.4 GB
 Data Space Available: 66.82 GB
 Metadata Space Used: 59.68 MB
 Metadata Space Total: 2.147 GB
 Metadata Space Available: 2.088 GB
 Thin Pool Minimum Free Space: 10.74 GB
 Udev Sync Supported: true
 Deferred Removal Enabled: false
 Deferred Deletion Enabled: false
 Deferred Deleted Device Count: 0
 Data loop file: /var/lib/docker/devicemapper/devicemapper/data
 WARNING: Usage of loopback devices is strongly discouraged for production use. Use `--storage-opt dm.thinpooldev` to specify a custom block storage device.
 Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata
 Library Version: 1.02.107-RHEL7 (2015-12-01)
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins: 
 Volume: local
 Network: overlay null host bridge
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: 
containerd version: 
runc version: 
init version: 
Security Options:
 seccomp
Kernel Version: 3.10.0-327.10.1.el7.x86_64
Operating System: CentOS Linux 7 (Core)
OSType: linux
Architecture: x86_64
CPUs: 8
Total Memory: 251.7 GiB
Name: meow
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false

the problem

I am writing some test fixtures using docker-py. The docker image I am running is exiting within seconds of starting because the command fails. In my test fixture I have a loop that attempts to wait until the service running in the container is ready to begin accepting queries. One of the things this loop does on each pass is to check the Container.status property of the container. No matter what, it always returns created. In my logic, created is an acceptable state for the Container object to be in since the created state seems to always precede the running state. I know the container is actually in exited state because I ran docker inspect -f '{{.State.Status}}' which returns exited.

My short term work around is going to be to simply call docker inspect -f '{{.State.Status}}' in my loop, but I thought it would be a good idea to file an issue here also. Actually, in retrospect I probably should have attempted docker 2.2.0 before filing this issue...

[waynr]

I've verified the same problem is showing up when I pin docker==2.2.0 in my test requirements file.

[shin-]

The value is cached. Call container.reload() to retrieve the updated status.

[waynr]

@shin- hmm, I don't see Container.reload() documented in https://docker-py.readthedocs.io/en/stable/containers.html

Also, if the values are cached--and it's not clear to me what the value of a cached status is since the reason someone would I want to check it more than once is to see if it changed since the last time--that fact should probably be documented.

[shin-]

Yes, the reload method was missing in our docs, that's now been fixed: http://docker-py.readthedocs.io/en/stable/containers.html#docker.models.containers.Container.reload

As to the rationale for caching, not all environments are low-latency, and server requests can be expensive, which is why it makes sense to me to give the developer control over when they want to retrieve new data from the remote with an explicit call. I hope that makes sense!

[waynr]

@shin- sure, that makes sense--thanks for updating the docs. I wonder if it would make sense to create a subclass of Container for the cache (or non-cache) use case. (just thinking out loud)