Why would `docker stop` kill the docker service? - jenkins

Question

Our CI infrastructure (Jenkins) builds and tests docker containers. We have found that stopping a container used during test takes the docker service offline, disconnecting the slave from our Jenkins master. Why would stopping the memcached container kill and restart the docker service?
What we see in the job:
+ docker stop memcached55c7e2ab363be9425039412edc81be1e8601c196
FATAL: java.io.IOException: Unexpected termination of the channel
hudson.remoting.RequestAbortedException: java.io.IOException: Unexpected termination of the channel
at hudson.remoting.Request.abort(Request.java:295)
at hudson.remoting.Channel.terminate(Channel.java:814)
/var/log/docker:
time="2015-07-29T11:43:07-04:00" level=info msg="POST /v1.18/containers/memcached55c7e2ab363be9425039412edc81be1e8601c196/stop?t=10"
time="2015-07-29T11:43:07-04:00" level=info msg="+job stop(memcached55c7e2ab363be9425039412edc81be1e8601c196)"
\nWed Jul 29 11:43:52 EDT 2015\n
time="2015-07-29T11:43:53-04:00" level=warning msg="You are running linux kernel version 2.6.32-504.30.3.el6.x86_64, which might be unstable running docker. Please upgrade your kernel to 3.8.0."
time="2015-07-29T11:43:53-04:00" level=info msg="+job serveapi(unix:///var/run/docker.sock)"
time="2015-07-29T11:43:53-04:00" level=info msg="Listening for HTTP on unix (/var/run/docker.sock)"
time="2015-07-29T11:43:53-04:00" level=info msg="+job init_networkdriver()"
time="2015-07-29T11:43:53-04:00" level=info msg="-job init_networkdriver() = OK (0)"
time="2015-07-29T11:43:53-04:00" level=info msg="Loading containers: start."
...time="2015-07-29T11:43:53-04:00" level=error msg="Error unmounting device 23607b95df9a186d80bb346c914cd01e7631c4fec3968bde29df7bc327f0b820: UnmountDevice: device not-mounted id 23607b95df9a186d80bb346c914cd01e7631c4fec3968bde29df7bc327f0b820"
.time="2015-07-29T11:43:53-04:00" level=error msg="Error unmounting device d01f73b589a9d598cc97752ce554b5c5dcf1b51d3991c1dee54880bb7d718fb7: UnmountDevice: device not-mounted id d01f73b589a9d598cc97752ce554b5c5dcf1b51d3991c1dee54880bb7d718fb7"
time="2015-07-29T11:43:53-04:00" level=info msg="Loading containers: done."
time="2015-07-29T11:43:53-04:00" level=info msg="docker daemon: 1.6.2 7c8fca2/1.6.2; execdriver: native-0.2; graphdriver: devicemapper"
time="2015-07-29T11:43:53-04:00" level=info msg="+job acceptconnections()"
time="2015-07-29T11:43:53-04:00" level=info msg="-job acceptconnections() = OK (0)"
time="2015-07-29T11:43:53-04:00" level=info msg="Daemon has completed initialization"
Versions:
-bash-4.1$ uname -a
Linux ip-172-17-70-142.ec2.internal 2.6.32-504.30.3.el6.x86_64 #1 SMP Wed Jul 15 10:13:09 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
-bash-4.1$ docker --version
Docker version 1.6.2, build 7c8fca2/1.6.2
-bash-4.1$ docker version
Client version: 1.6.2
Client API version: 1.18
Go version (client): go1.4.2
Git commit (client): 7c8fca2/1.6.2
OS/Arch (client): linux/amd64
Server version: 1.6.2
Server API version: 1.18
Go version (server): go1.4.2
Git commit (server): 7c8fca2/1.6.2
OS/Arch (server): linux/amd64
-bash-4.1$ docker info
Containers: 2
Images: 65
Storage Driver: devicemapper
Pool Name: docker-202:64-936887-pool
Pool Blocksize: 65.54 kB
Backing Filesystem: extfs
Data file: /dev/loop0
Metadata file: /dev/loop1
Data Space Used: 1.597 GB
Data Space Total: 107.4 GB
Data Space Available: 12.44 GB
Metadata Space Used: 3.584 MB
Metadata Space Total: 2.147 GB
Metadata Space Available: 2.144 GB
Udev Sync Supported: true
Data loop file: /var/lib/docker/devicemapper/devicemapper/data
Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata
Library Version: 1.02.89-RHEL6 (2014-09-01)
Execution Driver: native-0.2
Kernel Version: 2.6.32-504.30.3.el6.x86_64
Operating System: <unknown>
CPUs: 2
Total Memory: 7.166 GiB
Name: ip-172-17-70-142.ec2.internal
ID: X4UG:BKKW:5ZQX:VXRV:3GYP:FU3J:7FJC:4FFM:CK4D:SWSH:KIHW:IPNE
Username: dxbuildmaster
Registry: [https://index.docker.io/v1/]

Answer 1

Are you sure that this is caused by docker? We were using a Jenkins version in our environment that does not deal with docker at all and had the same error message. There is a known Jenkins bug about that which has been fixed in version 1.532.1. So which Jenkins version are you using?