blob: 78107156753f07ae7a0feccd8ec38f4dbd8188c6 [file] [log] [blame]
# DinD: a wrapper script which allows docker to be run inside a docker container.
# Original version by Jerome Petazzoni <>
# See the blog post:
# This script should be executed inside a docker container in privilieged mode
# ('docker run -privileged', introduced in docker 0.6).
# Usage: dind CMD [ARG...]
# First, make sure that cgroups are mounted correctly.
[ -d $CGROUP ] ||
mkdir $CGROUP
mountpoint -q $CGROUP ||
mount -n -t tmpfs -o uid=0,gid=0,mode=0755 cgroup $CGROUP || {
echo "Could not make a tmpfs mount. Did you use -privileged?"
exit 1
# Mount the cgroup hierarchies exactly as they are in the parent system.
for SUBSYS in $(cut -d: -f2 /proc/1/cgroup)
mountpoint -q $CGROUP/$SUBSYS ||
mount -n -t cgroup -o $SUBSYS cgroup $CGROUP/$SUBSYS
# Note: as I write those lines, the LXC userland tools cannot setup
# a "sub-container" properly if the "devices" cgroup is not in its
# own hierarchy. Let's detect this and issue a warning.
grep -q :devices: /proc/1/cgroup ||
echo "WARNING: the 'devices' cgroup should be in its own hierarchy."
grep -qw devices /proc/1/cgroup ||
echo "WARNING: it looks like the 'devices' cgroup is not mounted."
# Now, close extraneous file descriptors.
pushd /proc/self/fd
for FD in *
case "$FD" in
# Keep stdin/stdout/stderr
# Nuke everything else
eval exec "$FD>&-"
# Mount /tmp
mount -t tmpfs none /tmp
exec $*