There are good explanations on how to resolve this issue. SOF Q1, SOF Q2 and many more related questions on SOF and internet.
My worry is, what causes this issue and why docker ends up in this state. (/var/run contains run time data of an application i.e docker. Why is docker not able to connect/ or write here. If this point is not relevant... leave it.).
My concern is, our docker system was well working and stable for several days and suddenly we see this issue. I can not always ask the sys admins to restart docker or the linux server (process issues.. and of course I wan't to prevent it by having better understanding of docker ). So i got to prevent this issue from happening.
We are using fedora based linux and the docker version info is:
Server Version: 17.12.0-ce
Storage Driver: overlay2 Backing
Filesystem: extfs
Supports d_type: true
Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Can provide more docker info if require.