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: $bin" 1>&2
  33         exit 1
  34     fi
  35 done
  36
  37 LXC_TEMPLATE_CONFIG="@LXCTEMPLATECONFIG@"
  38
  39 # Some useful functions
  40 cleanup() {
  41     if [ -d "$DOWNLOAD_TEMP" ]; then
  42         rm -Rf $DOWNLOAD_TEMP
  43     fi
  44 }
  45
  46 in_userns() {
  47     [ -e /proc/self/uid_map ] || { echo no; return; }
  48     while read line; do
  49         fields=$(echo $line | awk '{ print $1 " " $2 " " $3 }')
  50         [ "$fields" = "0 0 4294967295" ] && { echo no; return; } || true
  51         echo $fields | grep -q " 0 1$" && { echo userns-root; return; } || true
  52     done < /proc/self/uid_map
  53
  54     [ "$(cat /proc/self/uid_map)" = "$(cat /proc/1/uid_map)" ] && \
  55         { echo userns-root; return; }
  56     echo yes
  57 }
  58
  59 getconfigpath() {
  60         basedir="$1"
  61         q="$2"
  62
  63         digest=`cat "${basedir}/index.json" | jq --arg q "$q" '.manifests[] | if .annotations."org.opencontainers.image.ref.name" == $q then .digest else null end' | sed -e 's/"//g'`
  64         if [ -z "${digest}" ]; then
  65                 echo "$q not found in index.json" >&2
  66                 return
  67         fi
  68
  69         # Ok we have the image config digest, now get the config from that,
  70         d=${digest:7}
  71         cdigest=`cat "${basedir}/blobs/sha256/${d}" | jq '.config.digest' | sed -e 's/"//g'`
  72         if [ -z "${cdigest}" ]; then
  73                 echo "container config not found" >&2
  74                 return
  75         fi
  76
  77         d2=${cdigest:7}
  78         echo "${basedir}/blobs/sha256/${d2}"
  79         return
  80 }
  81
  82 # get entrypoint from oci image.  Use sh if unspecified
  83 getep() {
  84         if [ "$#" -eq 0 ]; then
  85                 echo "/bin/sh"
  86                 return
  87         fi
  88
  89         configpath="$1"
  90
  91         ep=`cat "${configpath}" | jq -c '.config.Entrypoint' | sed -e 's/^\[//; s/\]$//; s/","/" "/'`
  92         cmd=`cat "${configpath}" | jq -c '.config.Cmd' | sed -e 's/^\[//; s/\]$//; s/","/" "/'`
  93         if [ "${ep}" = "null" ]; then
  94                 ep="${cmd}"
  95                 if [ "${ep}" = "null" ]; then
  96                         ep="/bin/sh"
  97                 fi
  98         elif [ "${cmd}" != "null" ]; then
  99                 ep="${ep} ${cmd}"
 100         fi
 101
 102         if [ -z "${ep}" ]; then
 103                 echo "/bin/sh"
 104                 return
 105         fi
 106         echo "${ep}"
 107         return
 108 }
 109
 110 # get environment from oci image.
 111 getenv() {
 112         if [ "$#" -eq 0 ]; then
 113                 return
 114         fi
 115
 116         configpath="$1"
 117
 118         cat "${configpath}" > /tmp/config
 119         env=`cat "${configpath}" | jq -c '.config.Env[]'`
 120
 121         echo "${env}"
 122         return
 123 }
 124
 125 usage() {
 126     cat <<EOF
 127 LXC container template for OCI images
 128
 129 Special arguments:
 130 [ -h | --help ]: Print this help message and exit.
 131
 132 Required arguments:
 133 [ -u | --url <url> ]: The OCI image URL
 134
 135 LXC internal arguments (do not pass manually!):
 136 [ --name <name> ]: The container name
 137 [ --path <path> ]: The path to the container
 138 [ --rootfs <rootfs> ]: The path to the container's rootfs
 139 [ --mapped-uid <map> ]: A uid map (user namespaces)
 140 [ --mapped-gid <map> ]: A gid map (user namespaces)
 141
 142 EOF
 143     return 0
 144 }
 145
 146 options=$(getopt -o u:h -l help,url:,name:,path:,\
 147 rootfs:,mapped-uid:,mapped-gid: -- "$@")
 148
 149 if [ $? -ne 0 ]; then
 150     usage
 151     exit 1
 152 fi
 153 eval set -- "$options"
 154
 155 OCI_URL=""
 156 LXC_MAPPED_GID=
 157 LXC_MAPPED_UID=
 158 LXC_NAME=
 159 LXC_PATH=
 160 LXC_ROOTFS=
 161
 162 while :; do
 163     case "$1" in
 164         -h|--help)          usage && exit 1;;
 165         -u|--url)           OCI_URL=$2; shift 2;;
 166         --name)             LXC_NAME=$2; shift 2;;
 167         --path)             LXC_PATH=$2; shift 2;;
 168         --rootfs)           LXC_ROOTFS=$2; shift 2;;
 169         --mapped-uid)       LXC_MAPPED_UID=$2; shift 2;;
 170         --mapped-gid)       LXC_MAPPED_GID=$2; shift 2;;
 171         *)                  break;;
 172     esac
 173 done
 174
 175 # Check that we have all variables we need
 176 if [ -z "$LXC_NAME" ] || [ -z "$LXC_PATH" ] || [ -z "$LXC_ROOTFS" ]; then
 177     echo "ERROR: Not running through LXC." 1>&2
 178     exit 1
 179 fi
 180
 181 if [ -z "$OCI_URL" ]; then
 182     echo "ERROR: no OCI URL given"
 183     exit 1
 184 fi
 185
 186 USERNS=$(in_userns)
 187
 188 if [ "$USERNS" != "no" ]; then
 189     if [ "$USERNS" = "yes" ]; then
 190         if [ -z "$LXC_MAPPED_UID" ] || [ "$LXC_MAPPED_UID" = "-1" ]; then
 191             echo "ERROR: In a user namespace without a map." 1>&2
 192             exit 1
 193         fi
 194         DOWNLOAD_MODE="user"
 195         DOWNLOAD_TARGET="user"
 196     else
 197         DOWNLOAD_MODE="user"
 198         DOWNLOAD_TARGET="system"
 199     fi
 200 fi
 201
 202 # Trap all exit signals
 203 trap cleanup EXIT HUP INT TERM
 204
 205 if ! type mktemp >/dev/null 2>&1; then
 206     DOWNLOAD_TEMP=/tmp/lxc-oci.$$
 207     mkdir -p $DOWNLOAD_TEMP
 208 else
 209     DOWNLOAD_TEMP=$(mktemp -d)
 210 fi
 211
 212 # Download the image - TODO - cache
 213 skopeo copy "${OCI_URL}" "oci:${DOWNLOAD_TEMP}:latest"
 214
 215 # Unpack the rootfs
 216 echo "Unpacking the rootfs"
 217
 218 umoci_args=("")
 219 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 220     umoci_args+=(--rootless)
 221 fi
 222 umoci unpack ${umoci_args[@]} --image "${DOWNLOAD_TEMP}:latest" "${LXC_ROOTFS}.tmp"
 223 rmdir "${LXC_ROOTFS}"
 224 mv "${LXC_ROOTFS}.tmp/rootfs" "${LXC_ROOTFS}"
 225 rm -rf "${LXC_ROOTFS}.tmp"
 226
 227 OCI_CONF_FILE=$(getconfigpath ${DOWNLOAD_TEMP} latest)
 228 LXC_CONF_FILE="${LXC_PATH}/config"
 229 entrypoint=$(getep ${OCI_CONF_FILE})
 230 echo "lxc.execute.cmd = '${entrypoint}'" >> "${LXC_CONF_FILE}"
 231 echo "lxc.mount.auto = proc:mixed sys:mixed cgroup:mixed" >> "${LXC_CONF_FILE}"
 232
 233 environment=$(getenv ${OCI_CONF_FILE})
 234 while read -r line; do
 235     echo "lxc.environment = ${line}" >> "${LXC_CONF_FILE}"
 236 done <<< "${environment}"
 237
 238 if [ -e "${LXC_TEMPLATE_CONFIG}/common.conf" ]; then
 239     echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/common.conf" >> "${LXC_CONF_FILE}"
 240 fi
 241
 242 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ] && [ -e "${LXC_TEMPLATE_CONFIG}/userns.conf" ]; then
 243     echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/userns.conf" >> "${LXC_CONF_FILE}"
 244 fi
 245
 246 echo "lxc.uts.name = ${LXC_NAME}" >> "${LXC_CONF_FILE}"
 247 # set the hostname
 248 cat <<EOF > ${LXC_ROOTFS}/etc/hostname
 249 ${LXC_NAME}
 250 EOF
 251
 252 # set minimal hosts
 253 cat <<EOF > ${LXC_ROOTFS}/etc/hosts
 254 127.0.0.1   localhost
 255 127.0.1.1   ${LXC_NAME}
 256 EOF
 257
 258 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 259     chown $LXC_MAPPED_UID $LXC_PATH/config $LXC_PATH/fstab >/dev/null 2>&1 || true
 260 fi
 261 if [ -n "$LXC_MAPPED_GID" ] && [ "$LXC_MAPPED_GID" != "-1" ]; then
 262     chgrp $LXC_MAPPED_GID $LXC_PATH/config $LXC_PATH/fstab >/dev/null 2>&1 || true
 263 fi
 264
 265 exit 0