#!/bin/sh
set -e

### BEGIN INIT INFO
# Provides:           docker
# Required-Start:     $syslog $remote_fs
# Required-Stop:      $syslog $remote_fs
# Should-Start:       cgroupfs-mount cgroup-lite
# Should-Stop:        cgroupfs-mount cgroup-lite
# Default-Start:      2 3 4 5
# Default-Stop:       0 1 6
# Short-Description:  Create lightweight, portable, self-sufficient containers.
# Description:
#  Docker is an open-source project to easily create lightweight, portable,
#  self-sufficient containers from any application. The same container that a
#  developer builds and tests on a laptop can run at scale, in production, on
#  VMs, bare metal, OpenStack clusters, public clouds and more.
### END INIT INFO

export PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin

BASE=$(basename $0)

# modify these in /etc/default/$BASE (/etc/default/docker)
DOCKER=/usr/bin/$BASE
# This is the pid file managed by docker itself
DOCKER_PIDFILE=/var/run/$BASE.pid
# This is the pid file created/managed by start-stop-daemon
DOCKER_SSD_PIDFILE=/var/run/$BASE-ssd.pid
DOCKER_LOGFILE=/var/log/$BASE.log
DOCKER_OPTS=
DOCKER_DESC="Docker"

# Get lsb functions
. /lib/lsb/init-functions

if [ -f /etc/default/$BASE ]; then
        . /etc/default/$BASE
fi

# Check docker is present
if [ ! -x $DOCKER ]; then
        log_failure_msg "$DOCKER not present or not executable"
        exit 1
fi

check_init() {
         # see also init_is_upstart in /lib/lsb/init-functions (which isn't available in Ubuntu 12.04, or we'd use it directly)
         if [ -x /sbin/initctl ] && /sbin/initctl version 2>/dev/null | grep -q upstart; then
                log_failure_msg "$DOCKER_DESC is managed via upstart, try using service $BASE $1"
                exit 1
         fi
}

fail_unless_root() {
        if [ "$(id -u)" != '0' ]; then
                log_failure_msg "$DOCKER_DESC must be run as root"
                exit 1
        fi
}

cgroupfs_mount() {
        # see also https://github.com/tianon/cgroupfs-mount/blob/master/cgroupfs-mount
        if grep -v '^#' /etc/fstab | grep -q cgroup \
                || [ ! -e /proc/cgroups ] \
                || [ ! -d /sys/fs/cgroup ]; then
                return
        fi
        if ! mountpoint -q /sys/fs/cgroup; then
                mount -t tmpfs -o uid=0,gid=0,mode=0755 cgroup /sys/fs/cgroup
        fi
        (
                cd /sys/fs/cgroup
                for sys in $(awk '!/^#/ { if ($4 == 1) print $1 }' /proc/cgroups); do
                        mkdir -p $sys
                        if ! mountpoint -q $sys; then
                                if ! mount -n -t cgroup -o $sys cgroup $sys; then
                                        rmdir $sys || true
                                fi
                        fi
                done
        )
}

case "$1" in
        start)
                check_init

                fail_unless_root

                cgroupfs_mount

                touch "$DOCKER_LOGFILE"
                chgrp docker "$DOCKER_LOGFILE"

                ulimit -n 1048576
                if [ "$BASH" ]; then
                        ulimit -u 1048576
                else
                        ulimit -p 1048576
                fi

                log_begin_msg "Starting $DOCKER_DESC: $BASE"
                start-stop-daemon --start --background \
                        --no-close \
                        --exec "$DOCKER" \
                        --pidfile "$DOCKER_SSD_PIDFILE" \
                        --make-pidfile \
                        -- \
                                -d -p "$DOCKER_PIDFILE" \
                                $DOCKER_OPTS \
                                        >> "$DOCKER_LOGFILE" 2>&1
                log_end_msg $?
                ;;

        stop)
                check_init
                fail_unless_root
                log_begin_msg "Stopping $DOCKER_DESC: $BASE"
                start-stop-daemon --stop --pidfile "$DOCKER_SSD_PIDFILE"
                log_end_msg $?
                ;;

        restart)
                check_init
                fail_unless_root
                docker_pid=`cat "$DOCKER_SSD_PIDFILE" 2>/dev/null`
                [ -n "$docker_pid" ] \
                        && ps -p $docker_pid > /dev/null 2>&1 \
                        && $0 stop
                $0 start
                ;;

        force-reload)
                check_init
                fail_unless_root
                $0 restart
                ;;

        status)
                check_init
                status_of_proc -p "$DOCKER_SSD_PIDFILE" "$DOCKER" "$DOCKER_DESC"
                ;;

        *)
                echo "Usage: service docker {start|stop|restart|status}"
                exit 1
                ;;
esac
