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moby--moby/hack/dind
Akihiro Suda 42b1175eda
hack/dind: fix cgroup v2 evacuation with docker run --init
Evacuate all the processes in `/sys/fs/cgroup/cgroup.procs`, not just PID 1.

Before:
```console
$ docker run --rm --privileged --init $(docker build -q .) cat /sys/fs/cgroup/cgroup.subtree_control
sed: couldn't flush stdout: Device or resource busy
```

After:
```console
$ docker run --rm --privileged --init $(docker build -q .) cat /sys/fs/cgroup/cgroup.subtree_control
cpuset cpu io memory hugetlb pids rdma
```

Fix docker-library/docker issue 308

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
2021-04-28 13:30:10 +09:00

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#!/bin/sh
set -e
# DinD: a wrapper script which allows docker to be run inside a docker container.
# Original version by Jerome Petazzoni <jerome@docker.com>
# See the blog post: https://blog.docker.com/2013/09/docker-can-now-run-within-docker/
#
# This script should be executed inside a docker container in privileged mode
# ('docker run --privileged', introduced in docker 0.6).
# Usage: dind CMD [ARG...]
# apparmor sucks and Docker needs to know that it's in a container (c) @tianon
export container=docker
if [ -d /sys/kernel/security ] && ! mountpoint -q /sys/kernel/security; then
mount -t securityfs none /sys/kernel/security || {
echo >&2 'Could not mount /sys/kernel/security.'
echo >&2 'AppArmor detection and --privileged mode might break.'
}
fi
# Mount /tmp (conditionally)
if ! mountpoint -q /tmp; then
mount -t tmpfs none /tmp
fi
# cgroup v2: enable nesting
if [ -f /sys/fs/cgroup/cgroup.controllers ]; then
# move the processes from the root group to the /init group,
# otherwise writing subtree_control fails with EBUSY.
# An error during moving non-existent process (i.e., "cat") is ignored.
mkdir -p /sys/fs/cgroup/init
xargs -rn1 < /sys/fs/cgroup/cgroup.procs > /sys/fs/cgroup/init/cgroup.procs || :
# enable controllers
sed -e 's/ / +/g' -e 's/^/+/' < /sys/fs/cgroup/cgroup.controllers \
> /sys/fs/cgroup/cgroup.subtree_control
fi
if [ $# -gt 0 ]; then
exec "$@"
fi
echo >&2 'ERROR: No command specified.'
echo >&2 'You probably want to run hack/make.sh, or maybe a shell?'