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#!/bin/bash |
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# First, make sure that cgroups are mounted correctly. |
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CGROUP=/sys/fs/cgroup |
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: {LOG:=stdio} |
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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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if [ -d /sys/kernel/security ] && ! mountpoint -q /sys/kernel/security |
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then |
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mount -t securityfs none /sys/kernel/security || { |
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echo "Could not mount /sys/kernel/security." |
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echo "AppArmor detection and -privileged mode might break." |
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} |
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fi |
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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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# If a pidfile is still around (for example after a container restart), |
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# delete it so that docker can start. |
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rm -rf /var/run/docker.pid |
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nohup docker \ |
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-d $DOCKER_DAEMON_ARGS \ |
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-H tcp://0.0.0.0:2375 \ |
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-H unix:///var/run/docker.sock \ |
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&>/var/log/docker.log & |