From 255b6aadfacfd346ef413a1ffd945360276cbcf6 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Petazzoni?= Date: Thu, 17 Oct 2013 20:32:23 -0700 Subject: [PATCH] Work around an exotic bug affecting Docker-in-Docker + systemd. --- hack/dind | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/hack/dind b/hack/dind index 7810715675..e8b715cc9c 100755 --- a/hack/dind +++ b/hack/dind @@ -27,6 +27,31 @@ do [ -d $CGROUP/$SUBSYS ] || mkdir $CGROUP/$SUBSYS mountpoint -q $CGROUP/$SUBSYS || mount -n -t cgroup -o $SUBSYS cgroup $CGROUP/$SUBSYS + + # The two following sections address a bug which manifests itself + # by a cryptic "lxc-start: no ns_cgroup option specified" when + # trying to start containers withina container. + # The bug seems to appear when the cgroup hierarchies are not + # mounted on the exact same directories in the host, and in the + # container. + + # Named, control-less cgroups are mounted with "-o name=foo" + # (and appear as such under /proc//cgroup) but are usually + # mounted on a directory named "foo" (without the "name=" prefix). + # Systemd and OpenRC (and possibly others) both create such a + # cgroup. To avoid the aforementioned bug, we symlink "foo" to + # "name=foo". This shouldn't have any adverse effect. + echo $SUBSYS | grep -q ^name= && { + NAME=$(echo $SUBSYS | sed s/^name=//) + ln -s $SUBSYS $CGROUP/$NAME + } + + # Likewise, on at least one system, it has been reported that + # systemd would mount the CPU and CPU accounting controllers + # (respectively "cpu" and "cpuacct") with "-o cpuacct,cpu" + # but on a directory called "cpu,cpuacct" (note the inversion + # in the order of the groups). This tries to work around it. + [ $SUBSYS = cpuacct,cpu ] && ln -s $SUBSYS $CGROUP/cpu,cpuacct done # Note: as I write those lines, the LXC userland tools cannot setup