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