sockets - /var/run/docker.sock unaccessible in container running on centos 7 -

i'm launching container runs bash script docker build internally using docker 1.3.2 on centos 7.0.1406 . files/commands @ https://gist.github.com/wrabbit-revisited/1d70d0f1805be1848c08 .

the docker build needs access docker socket use common trick, per http://nathanleclaire.com/blog/2014/07/12/10-docker-tips-and-tricks-that-will-make-you-sing-a-whale-song-of-joy/ :

-v /var/run/docker.sock:/var/run/docker.sock 

prior build run check in script:

if [ -e "/var/run/docker.sock" ];   echo "docker.sock found" else   echo "docker.sock not found" fi 

and "echo" shows docker.sock not found. found if check done outside container using sudo.

i tried adding "--permissive=true" "docker run" command line, no apparent change.

there reference similar problem here: https://github.com/dpw/selinux-dockersock . targets fedora/rhel, doesn't resolve issue, either. if use "setenforce permissive" , sestatus ensure selinux in permissive mode issue remains unresolved.

i've tried adding "--security-opt=label:type:docker_t" docker command line, per https://github.com/jwilder/nginx-proxy/issues/40 . no apparent effect.

the selinux policy docker described here: http://www.unix.com/man-page/centos/8/docker_selinux/ .

lots of information, i'm not sure if selinux contributing problem. if edit /etc/selinux/config disable selinux reboot , run sestatus says selinux disabled, issue remains.

looking about, may related this: https://github.com/docker/compose/issues/983 . using trick run docker inside container quite common perhaps there better way or workaround. considered dind, that's work , widely-used, simple (on surface), approach running docker build inside container. there simple solution.

any appreciated! thanks

i think problem might due misunderstanding of -v option docker run. did

-v /var/run/docker:/var/run/docker 

this creates bind mount in container file or directory /var/run/docker. in case, there no such file or directory. want file /var/run/docker.sock. need do

-v /var/run/docker.sock:/var/run/docker.sock 

to bind mount file container.

as /var/run/docker didn't exist, might wonder why docker didn't tell error. -v option has surprising behaviour if path not exist on host, docker create directory. end useless empty /var/run/docker directory on host , container.

in principle, -v /var/run:/var/run bind mount containing directory. it's bad idea give container access host's /var/run directory tree.

and on centos, need use https://github.com/dpw/selinux-dockersock access /var/run/docker.sock work selinux in enforcing mode.