Docker daemon do not respond for images, containers is OK

General Discussions
1

–> docker --version
Docker version 1.8.2-el7, build a01dc02/1.8.2
–>docker info
Containers: 1
Images: 201
Storage Driver: devicemapper
Pool Name: docker-8:5-265450-pool
Pool Blocksize: 65.54 kB
Backing Filesystem: extfs
Data file: /dev/loop0
Metadata file: /dev/loop1
Data Space Used: 7.784 GB
Data Space Total: 107.4 GB
Data Space Available: 55.18 GB
Metadata Space Used: 12.53 MB
Metadata Space Total: 2.147 GB
Metadata Space Available: 2.135 GB
Udev Sync Supported: true
Deferred Removal Enabled: false
Data loop file: /var/lib/docker/devicemapper/devicemapper/data
Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata
Library Version: 1.02.107-RHEL7 (2015-10-14)
Execution Driver: native-0.2
Logging Driver: json-file
Kernel Version: 3.10.0-327.3.1.el7.x86_64
Operating System: Red Hat Enterprise Linux Server 7.2 (Maipo)
CPUs: 48
Total Memory: 125.7 GiB
Name: koj1-mc1
ID: WL4T:JYCM:5N7J:WAQ2:RLKT:JFWV:LIM6:LP7V:AXM3:UHPS:WXT7:QPSR
Debug mode (server): true
File Descriptors: 90
Goroutines: 94
System Time: 2016-08-01T04:03:23.694711445Z
EventsListeners: 0
Init SHA1: f7bb40c7220474256047ddbd63b447496387e4d2
Init Path: /usr/libexec/docker/dockerinit
Docker Root Dir: /var/lib/docker

  1. “docker ps/docker info” works OK
  2. “docker images” responds too slow, say about 2-4 minutes. Sometimes it do not responds at all.

Note: after restarting docker daemon, “docker images” works correctly for some time.
Then problem "2): occurs

2

Found the reason for slow response:-
We were using pacemaker with docker resource agent. The resource agent uses “docker inspect” while monitoring docker resources. “docker inspect” hits both containers and images api to look for the name provided. In case of images, it also tries to look the registry specified in docker configuration.

The default registry provided in our environment was of “redhat” and there was no net connectivity in our environment so it took time. If too many wrong hits are done in the specified case, docker stops responding, may be some socket issue, but i am not sure.