templates/lxc-oci.in

   1 #!/bin/bash
   2
   3 # Create application containers from OCI images
   4
   5 # Copyright © 2014 Stéphane Graber <stgraber@ubuntu.com>
   6 # Copyright © 2017 Serge Hallyn <serge@hallyn.com>
   7 #
   8 #  This library is free software; you can redistribute it and/or
   9 #  modify it under the terms of the GNU Lesser General Public
  10 #  License as published by the Free Software Foundation; either
  11 #  version 2.1 of the License, or (at your option) any later version.
  12
  13 #  This library is distributed in the hope that it will be useful,
  14 #  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 #  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 #  Lesser General Public License for more details.
  17
  18 #  You should have received a copy of the GNU Lesser General Public
  19 #  License along with this library; if not, write to the Free Software
  20 #  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
  21 #  USA
  22
  23 set -eu
  24 # set -x  # debug
  25
  26 # Make sure the usual locations are in PATH
  27 export PATH=$PATH:/usr/sbin:/usr/bin:/sbin:/bin
  28
  29 # Check for required binaries
  30 for bin in skopeo umoci jq; do
  31     if ! type $bin >/dev/null 2>&1; then
  32         echo "ERROR: Missing required tool: $bin" 1>&2
  33         exit 1
  34     fi
  35 done
  36
  37 # Some useful functions
  38 cleanup() {
  39     if [ -d "$DOWNLOAD_TEMP" ]; then
  40         rm -Rf $DOWNLOAD_TEMP
  41     fi
  42 }
  43
  44 in_userns() {
  45     [ -e /proc/self/uid_map ] || { echo no; return; }
  46     while read line; do
  47         fields=$(echo $line | awk '{ print $1 " " $2 " " $3 }')
  48         [ "$fields" = "0 0 4294967295" ] && { echo no; return; } || true
  49         echo $fields | grep -q " 0 1$" && { echo userns-root; return; } || true
  50     done < /proc/self/uid_map
  51
  52     [ "$(cat /proc/self/uid_map)" = "$(cat /proc/1/uid_map)" ] && \
  53         { echo userns-root; return; }
  54     echo yes
  55 }
  56
  57 # get entrypoint from oci image.  Use sh if unspecified
  58 # TODO - we can get other things like resource limits here
  59 getep() {
  60         basedir="$1"
  61         q="$2"
  62
  63
  64         digest=`cat "${basedir}/index.json" | jq --arg q "$q" '.manifests[] | if .annotations."org.opencontainers.image.ref.name" == $q then .digest else null end' | sed -e 's/"//g'`
  65         if [ -z "${digest}" ]; then
  66                 echo "$q not found in index.json" >&2
  67                 echo "/bin/sh"
  68                 return
  69         fi
  70
  71         # Ok we have the image config digest, now get the config from that,
  72         d=${digest:7}
  73         cdigest=`cat "${basedir}/blobs/sha256/${d}" | jq '.config.digest' | sed -e 's/"//g'`
  74         if [ -z "${cdigest}" ]; then
  75                 echo "container config not found" >&2
  76                 echo "/bin/sh"
  77                 return
  78         fi
  79
  80         d2=${cdigest:7}
  81         ep=`cat "${basedir}/blobs/sha256/${d2}" | jq -c '.config.Entrypoint' | sed -e 's/^\[//; s/\]$//; s/","/" "/'`
  82         cmd=`cat "${basedir}/blobs/sha256/${d2}" | jq -c '.config.Cmd' | sed -e 's/^\[//; s/\]$//; s/","/" "/'`
  83         if [ "${ep}" = "null" ]; then
  84                 ep="${cmd}"
  85                 if [ "${ep}" = "null" ]; then
  86                         ep="/bin/sh"
  87                 fi
  88         elif [ "${cmd}" != "null" ]; then
  89                 ep="${ep} ${cmd}"
  90         fi
  91
  92         if [ -z "${ep}" ]; then
  93                 echo "/bin/sh"
  94                 return
  95         fi
  96         echo "${ep}"
  97         return
  98 }
  99
 100 usage() {
 101     cat <<EOF
 102 LXC container template for OCI images
 103
 104 Special arguments:
 105 [ -h | --help ]: Print this help message and exit.
 106
 107 Required arguments:
 108 [ -u | --url <url> ]: The OCI image URL
 109
 110 LXC internal arguments (do not pass manually!):
 111 [ --name <name> ]: The container name
 112 [ --path <path> ]: The path to the container
 113 [ --rootfs <rootfs> ]: The path to the container's rootfs
 114 [ --mapped-uid <map> ]: A uid map (user namespaces)
 115 [ --mapped-gid <map> ]: A gid map (user namespaces)
 116
 117 EOF
 118     return 0
 119 }
 120
 121 options=$(getopt -o u:h -l help,url:,name:,path:,\
 122 rootfs:,mapped-uid:,mapped-gid: -- "$@")
 123
 124 if [ $? -ne 0 ]; then
 125     usage
 126     exit 1
 127 fi
 128 eval set -- "$options"
 129
 130 OCI_URL=""
 131 LXC_MAPPED_GID=
 132 LXC_MAPPED_UID=
 133 LXC_NAME=
 134 LXC_PATH=
 135 LXC_ROOTFS=
 136
 137 while :; do
 138     case "$1" in
 139         -h|--help)          usage && exit 1;;
 140         -u|--url)           OCI_URL=$2; shift 2;;
 141         --name)             LXC_NAME=$2; shift 2;;
 142         --path)             LXC_PATH=$2; shift 2;;
 143         --rootfs)           LXC_ROOTFS=$2; shift 2;;
 144         --mapped-uid)       LXC_MAPPED_UID=$2; shift 2;;
 145         --mapped-gid)       LXC_MAPPED_GID=$2; shift 2;;
 146         *)                  break;;
 147     esac
 148 done
 149
 150 # Check that we have all variables we need
 151 if [ -z "$LXC_NAME" ] || [ -z "$LXC_PATH" ] || [ -z "$LXC_ROOTFS" ]; then
 152     echo "ERROR: Not running through LXC." 1>&2
 153     exit 1
 154 fi
 155
 156 if [ -z "$OCI_URL" ]; then
 157     echo "ERROR: no OCI URL given"
 158     exit 1
 159 fi
 160
 161 USERNS=$(in_userns)
 162
 163 if [ "$USERNS" != "no" ]; then
 164     if [ "$USERNS" = "yes" ]; then
 165         if [ -z "$LXC_MAPPED_UID" ] || [ "$LXC_MAPPED_UID" = "-1" ]; then
 166             echo "ERROR: In a user namespace without a map." 1>&2
 167             exit 1
 168         fi
 169         DOWNLOAD_MODE="user"
 170         DOWNLOAD_TARGET="user"
 171     else
 172         DOWNLOAD_MODE="user"
 173         DOWNLOAD_TARGET="system"
 174     fi
 175 fi
 176
 177 # Trap all exit signals
 178 trap cleanup EXIT HUP INT TERM
 179
 180 if ! type mktemp >/dev/null 2>&1; then
 181     DOWNLOAD_TEMP=/tmp/lxc-oci.$$
 182     mkdir -p $DOWNLOAD_TEMP
 183 else
 184     DOWNLOAD_TEMP=$(mktemp -d)
 185 fi
 186
 187 # Download the image - TODO - cache
 188 skopeo copy "${OCI_URL}" "oci:${DOWNLOAD_TEMP}:latest"
 189
 190 # Unpack the rootfs
 191 echo "Unpacking the rootfs"
 192
 193 umoci unpack --image "${DOWNLOAD_TEMP}:latest" "${LXC_ROOTFS}.tmp"
 194 rmdir "${LXC_ROOTFS}"
 195 mv "${LXC_ROOTFS}.tmp/rootfs" "${LXC_ROOTFS}"
 196 entrypoint=$(getep ${DOWNLOAD_TEMP} latest)
 197 rm -rf "${LXC_ROOTFS}.tmp"
 198
 199 LXC_CONF_FILE="${LXC_PATH}/config"
 200 echo "lxc.execute.cmd = '${entrypoint}'" >> "${LXC_CONF_FILE}"
 201 echo "lxc.mount.auto = proc:mixed sys:mixed cgroup:mixed" >> "${LXC_CONF_FILE}"
 202
 203 echo "lxc.uts.name = ${LXC_NAME}" >> ${LXC_PATH}/config
 204
 205 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 206     chown $LXC_MAPPED_UID $LXC_PATH/config $LXC_PATH/fstab >/dev/null 2>&1 || true
 207 fi
 208 if [ -n "$LXC_MAPPED_GID" ] && [ "$LXC_MAPPED_GID" != "-1" ]; then
 209     chgrp $LXC_MAPPED_GID $LXC_PATH/config $LXC_PATH/fstab >/dev/null 2>&1 || true
 210 fi
 211
 212 exit 0