feat: wrapdocker script

containers/dind/containers/dind/wrapdocker

+#!/bin/bash
+
+# Ensure that all nodes in /dev/mapper correspond to mapped devices currently loaded by the device-mapper kernel driver
+dmsetup mknodes
+
+# First, make sure that cgroups are mounted correctly.
+CGROUP=/sys/fs/cgroup
+: {LOG:=stdio}
+
+[ -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
+	}
+
+if [ -d /sys/kernel/security ] && ! mountpoint -q /sys/kernel/security
+then
+    mount -t securityfs none /sys/kernel/security || {
+        echo "Could not mount /sys/kernel/security."
+        echo "AppArmor detection and --privileged mode might break."
+    }
+fi
+
+# Mount the cgroup hierarchies exactly as they are in the parent system.
+for SUBSYS in $(cut -d: -f2 /proc/1/cgroup)
+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/<pid>/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 $CGROUP/cpu,cpuacct
+done
+
+# Note: as I write those lines, the LXC userland tools cannot setup
+# a "sub-container" properly if the "devices" cgroup is not in its
+# own hierarchy. Let's detect this and issue a warning.
+grep -q :devices: /proc/1/cgroup ||
+	echo "WARNING: the 'devices' cgroup should be in its own hierarchy."
+grep -qw devices /proc/1/cgroup ||
+	echo "WARNING: it looks like the 'devices' cgroup is not mounted."
+
+# Now, close extraneous file descriptors.
+pushd /proc/self/fd >/dev/null
+for FD in *
+do
+	case "$FD" in
+	# Keep stdin/stdout/stderr
+	[012])
+		;;
+	# Nuke everything else
+	*)
+		eval exec "$FD>&-"
+		;;
+	esac
+done
+popd >/dev/null
+
+
+# If a pidfile is still around (for example after a container restart),
+# delete it so that docker can start.
+rm -rf /var/run/docker.pid
+
+# If we were given a PORT environment variable, start as a simple daemon;
+# otherwise, spawn a shell as well
+if [ "$PORT" ]
+then
+	exec dockerd -H 0.0.0.0:$PORT -H unix:///var/run/docker.sock \
+		$DOCKER_DAEMON_ARGS
+else
+	if [ "$LOG" == "file" ]
+	then
+		dockerd $DOCKER_DAEMON_ARGS &>/var/log/docker.log &
+	else
+		dockerd $DOCKER_DAEMON_ARGS &
+	fi
+	(( timeout = 60 + SECONDS ))
+	until docker info >/dev/null 2>&1
+	do
+		if (( SECONDS >= timeout )); then
+			echo 'Timed out trying to connect to internal docker host.' >&2
+			break
+		fi
+		sleep 1
+	done
+	[[ $1 ]] && exec "$@"
+	exec bash --login
+fi