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 "${DOWNLOAD_TEMP}"
  43     fi
  44     if [ -d "${LXC_ROOTFS}.tmp" ]; then
  45         rm -Rf "${LXC_ROOTFS}.tmp"
  46     fi
  47 }
  48
  49 in_userns() {
  50     [ -e /proc/self/uid_map ] || { echo no; return; }
  51     while read line; do
  52         fields=$(echo $line | awk '{ print $1 " " $2 " " $3 }')
  53         [ "$fields" = "0 0 4294967295" ] && { echo no; return; } || true
  54         echo $fields | grep -q " 0 1$" && { echo userns-root; return; } || true
  55     done < /proc/self/uid_map
  56
  57     [ "$(cat /proc/self/uid_map)" = "$(cat /proc/1/uid_map)" ] && \
  58         { echo userns-root; return; }
  59     echo yes
  60 }
  61
  62 getconfigpath() {
  63         basedir="$1"
  64         q="$2"
  65
  66         digest=`cat "${basedir}/index.json" | jq -c -r --arg q "$q" '.manifests[] | if .annotations."org.opencontainers.image.ref.name" == $q then .digest else empty end'`
  67         if [ -z "${digest}" ]; then
  68                 echo "$q not found in index.json" >&2
  69                 return
  70         fi
  71
  72         # Ok we have the image config digest, now get the config from that,
  73         d=${digest:7}
  74         cdigest=`cat "${basedir}/blobs/sha256/${d}" | jq -c -r '.config.digest'`
  75         if [ -z "${cdigest}" ]; then
  76                 echo "container config not found" >&2
  77                 return
  78         fi
  79
  80         d2=${cdigest:7}
  81         echo "${basedir}/blobs/sha256/${d2}"
  82         return
  83 }
  84
  85 # get entrypoint from oci image.  Use sh if unspecified
  86 getep() {
  87         if [ "$#" -eq 0 ]; then
  88                 echo "/bin/sh"
  89                 return
  90         fi
  91
  92         configpath="$1"
  93
  94         ep=`cat "${configpath}" | jq -c -r '.config.Entrypoint[]?'`
  95         cmd=`cat "${configpath}" | jq -c -r '.config.Cmd[]?'`
  96         if [ -z "${ep}" ]; then
  97                 ep="${cmd}"
  98                 if [ -z "${ep}" ]; then
  99                         ep="/bin/sh"
 100                 fi
 101         elif [ -n "${cmd}" ]; then
 102                 ep="${ep} ${cmd}"
 103         fi
 104
 105         echo ${ep}
 106         return
 107 }
 108
 109 # get environment from oci image.
 110 getenv() {
 111         if [ "$#" -eq 0 ]; then
 112                 return
 113         fi
 114
 115         configpath="$1"
 116
 117         env=`cat "${configpath}" | jq -c -r '.config.Env[]'`
 118
 119         echo "${env}"
 120         return
 121 }
 122
 123 usage() {
 124     cat <<EOF
 125 LXC container template for OCI images
 126
 127 Special arguments:
 128 [ -h | --help ]: Print this help message and exit.
 129
 130 Required arguments:
 131 [ -u | --url <url> ]: The OCI image URL
 132
 133 Optional arguments:
 134 [ --username <username> ]: The username for the registry
 135 [ --password <password> ]: The password for the registry
 136
 137 LXC internal arguments (do not pass manually!):
 138 [ --name <name> ]: The container name
 139 [ --path <path> ]: The path to the container
 140 [ --rootfs <rootfs> ]: The path to the container's rootfs
 141 [ --mapped-uid <map> ]: A uid map (user namespaces)
 142 [ --mapped-gid <map> ]: A gid map (user namespaces)
 143
 144 EOF
 145     return 0
 146 }
 147
 148 options=$(getopt -o u:h -l help,url:,username:,password:,\
 149 name:,path:,rootfs:,mapped-uid:,mapped-gid: -- "$@")
 150
 151 if [ $? -ne 0 ]; then
 152     usage
 153     exit 1
 154 fi
 155 eval set -- "$options"
 156
 157 OCI_URL=""
 158 OCI_USERNAME=
 159 OCI_PASSWORD=
 160
 161 LXC_MAPPED_GID=
 162 LXC_MAPPED_UID=
 163 LXC_NAME=
 164 LXC_PATH=
 165 LXC_ROOTFS=
 166
 167 while :; do
 168     case "$1" in
 169         -h|--help)          usage && exit 1;;
 170         -u|--url)           OCI_URL=$2; shift 2;;
 171         --username)         OCI_USERNAME=$2; shift 2;;
 172         --password)         OCI_PASSWORD=$2; shift 2;;
 173         --name)             LXC_NAME=$2; shift 2;;
 174         --path)             LXC_PATH=$2; shift 2;;
 175         --rootfs)           LXC_ROOTFS=$2; shift 2;;
 176         --mapped-uid)       LXC_MAPPED_UID=$2; shift 2;;
 177         --mapped-gid)       LXC_MAPPED_GID=$2; shift 2;;
 178         *)                  break;;
 179     esac
 180 done
 181
 182 # Check that we have all variables we need
 183 if [ -z "$LXC_NAME" ] || [ -z "$LXC_PATH" ] || [ -z "$LXC_ROOTFS" ]; then
 184     echo "ERROR: Not running through LXC." 1>&2
 185     exit 1
 186 fi
 187
 188 if [ -z "$OCI_URL" ]; then
 189     echo "ERROR: no OCI URL given"
 190     exit 1
 191 fi
 192
 193 if [ -n "$OCI_PASSWORD" ] && [ -z "$OCI_USERNAME" ]; then
 194     echo "ERROR: password given but no username specified"
 195     exit 1
 196 fi
 197
 198 USERNS=$(in_userns)
 199
 200 if [ "$USERNS" != "no" ]; then
 201     if [ "$USERNS" = "yes" ]; then
 202         if [ -z "$LXC_MAPPED_UID" ] || [ "$LXC_MAPPED_UID" = "-1" ]; then
 203             echo "ERROR: In a user namespace without a map." 1>&2
 204             exit 1
 205         fi
 206         DOWNLOAD_MODE="user"
 207         DOWNLOAD_TARGET="user"
 208     else
 209         DOWNLOAD_MODE="user"
 210         DOWNLOAD_TARGET="system"
 211     fi
 212 fi
 213
 214 # Trap all exit signals
 215 trap cleanup EXIT HUP INT TERM
 216
 217 if ! type mktemp >/dev/null 2>&1; then
 218     DOWNLOAD_TEMP=/tmp/lxc-oci.$$
 219     mkdir -p $DOWNLOAD_TEMP
 220 else
 221     DOWNLOAD_TEMP=$(mktemp -d)
 222 fi
 223
 224 # Download the image - TODO - cache
 225 skopeo_args=("")
 226 if [ -n "$OCI_USERNAME" ]; then
 227     CREDENTIALS="${OCI_USERNAME}"
 228     if [ -n "$OCI_PASSWORD" ]; then
 229         CREDENTIALS="${CREDENTIALS}:${OCI_PASSWORD}"
 230     fi
 231     skopeo_args+=(--src-creds "${CREDENTIALS}")
 232 fi
 233 skopeo copy ${skopeo_args[@]} "${OCI_URL}" "oci:${DOWNLOAD_TEMP}:latest"
 234
 235 echo "Unpacking the rootfs"
 236 umoci_args=("")
 237 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 238     umoci_args+=(--rootless)
 239 fi
 240 umoci unpack ${umoci_args[@]} --image "${DOWNLOAD_TEMP}:latest" "${LXC_ROOTFS}.tmp"
 241 rmdir "${LXC_ROOTFS}"
 242 mv "${LXC_ROOTFS}.tmp/rootfs" "${LXC_ROOTFS}"
 243
 244 OCI_CONF_FILE=$(getconfigpath ${DOWNLOAD_TEMP} latest)
 245 LXC_CONF_FILE="${LXC_PATH}/config"
 246 entrypoint=$(getep ${OCI_CONF_FILE})
 247 echo "lxc.execute.cmd = '${entrypoint}'" >> "${LXC_CONF_FILE}"
 248 echo "lxc.mount.auto = proc:mixed sys:mixed cgroup:mixed" >> "${LXC_CONF_FILE}"
 249
 250 environment=$(getenv ${OCI_CONF_FILE})
 251 while read -r line; do
 252     echo "lxc.environment = ${line}" >> "${LXC_CONF_FILE}"
 253 done <<< "${environment}"
 254
 255 if [ -e "${LXC_TEMPLATE_CONFIG}/common.conf" ]; then
 256     echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/common.conf" >> "${LXC_CONF_FILE}"
 257 fi
 258
 259 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ] && [ -e "${LXC_TEMPLATE_CONFIG}/userns.conf" ]; then
 260     echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/userns.conf" >> "${LXC_CONF_FILE}"
 261 fi
 262
 263 echo "lxc.uts.name = ${LXC_NAME}" >> "${LXC_CONF_FILE}"
 264 # set the hostname
 265 cat <<EOF > ${LXC_ROOTFS}/etc/hostname
 266 ${LXC_NAME}
 267 EOF
 268
 269 # set minimal hosts
 270 cat <<EOF > ${LXC_ROOTFS}/etc/hosts
 271 127.0.0.1   localhost
 272 127.0.1.1   ${LXC_NAME}
 273 EOF
 274
 275 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 276     chown $LXC_MAPPED_UID $LXC_PATH/config $LXC_PATH/fstab >/dev/null 2>&1 || true
 277 fi
 278 if [ -n "$LXC_MAPPED_GID" ] && [ "$LXC_MAPPED_GID" != "-1" ]; then
 279     chgrp $LXC_MAPPED_GID $LXC_PATH/config $LXC_PATH/fstab >/dev/null 2>&1 || true
 280 fi
 281
 282 exit 0