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85 lines
2.8 KiB
Bash
Executable file
85 lines
2.8 KiB
Bash
Executable file
#!/bin/bash
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# DinD: a wrapper script which allows docker to be run inside a docker container.
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# Original version by Jerome Petazzoni <jerome@dotcloud.com>
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# See the blog post: http://blog.docker.io/2013/09/docker-can-now-run-within-docker/
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#
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# This script should be executed inside a docker container in privilieged mode
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# ('docker run -privileged', introduced in docker 0.6).
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# Usage: dind CMD [ARG...]
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# First, make sure that cgroups are mounted correctly.
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CGROUP=/sys/fs/cgroup
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[ -d $CGROUP ] ||
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mkdir $CGROUP
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mountpoint -q $CGROUP ||
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mount -n -t tmpfs -o uid=0,gid=0,mode=0755 cgroup $CGROUP || {
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echo "Could not make a tmpfs mount. Did you use -privileged?"
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exit 1
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}
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# Mount the cgroup hierarchies exactly as they are in the parent system.
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for SUBSYS in $(cut -d: -f2 /proc/1/cgroup)
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do
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[ -d $CGROUP/$SUBSYS ] || mkdir $CGROUP/$SUBSYS
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mountpoint -q $CGROUP/$SUBSYS ||
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mount -n -t cgroup -o $SUBSYS cgroup $CGROUP/$SUBSYS
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# The two following sections address a bug which manifests itself
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# by a cryptic "lxc-start: no ns_cgroup option specified" when
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# trying to start containers withina container.
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# The bug seems to appear when the cgroup hierarchies are not
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# mounted on the exact same directories in the host, and in the
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# container.
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# Named, control-less cgroups are mounted with "-o name=foo"
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# (and appear as such under /proc/<pid>/cgroup) but are usually
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# mounted on a directory named "foo" (without the "name=" prefix).
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# Systemd and OpenRC (and possibly others) both create such a
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# cgroup. To avoid the aforementioned bug, we symlink "foo" to
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# "name=foo". This shouldn't have any adverse effect.
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echo $SUBSYS | grep -q ^name= && {
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NAME=$(echo $SUBSYS | sed s/^name=//)
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ln -s $SUBSYS $CGROUP/$NAME
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}
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# Likewise, on at least one system, it has been reported that
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# systemd would mount the CPU and CPU accounting controllers
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# (respectively "cpu" and "cpuacct") with "-o cpuacct,cpu"
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# but on a directory called "cpu,cpuacct" (note the inversion
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# in the order of the groups). This tries to work around it.
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[ $SUBSYS = cpuacct,cpu ] && ln -s $SUBSYS $CGROUP/cpu,cpuacct
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done
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# Note: as I write those lines, the LXC userland tools cannot setup
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# a "sub-container" properly if the "devices" cgroup is not in its
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# own hierarchy. Let's detect this and issue a warning.
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grep -q :devices: /proc/1/cgroup ||
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echo "WARNING: the 'devices' cgroup should be in its own hierarchy."
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grep -qw devices /proc/1/cgroup ||
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echo "WARNING: it looks like the 'devices' cgroup is not mounted."
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# Now, close extraneous file descriptors.
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pushd /proc/self/fd >/dev/null
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for FD in *
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do
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case "$FD" in
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# Keep stdin/stdout/stderr
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[012])
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;;
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# Nuke everything else
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*)
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eval exec "$FD>&-"
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;;
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esac
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done
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popd >/dev/null
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# Mount /tmp
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mount -t tmpfs none /tmp
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[ "$1" ] && exec "$@"
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echo "You probably want to run hack/make.sh, or maybe a shell?"
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