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
  25 # Make sure the usual locations are in PATH
  26 export PATH=$PATH:/usr/sbin:/usr/bin:/sbin:/bin
  27
  28 # Check for required binaries
  29 for bin in skopeo umoci jq; do
  30   if ! which $bin >/dev/null 2>&1; then
  31     echo "ERROR: Missing required tool: $bin" 1>&2
  32     exit 1
  33   fi
  34 done
  35
  36 LOCALSTATEDIR="@LOCALSTATEDIR@"
  37 LXC_TEMPLATE_CONFIG="@LXCTEMPLATECONFIG@"
  38 LXC_HOOK_DIR="@LXCHOOKDIR@"
  39
  40 # Some useful functions
  41 cleanup() {
  42   if [ -d "${DOWNLOAD_TEMP}" ]; then
  43     rm -Rf "${DOWNLOAD_TEMP}"
  44   fi
  45
  46   if [ -d "${LXC_ROOTFS}.tmp" ]; then
  47     rm -Rf "${LXC_ROOTFS}.tmp"
  48   fi
  49 }
  50
  51 in_userns() {
  52   [ -e /proc/self/uid_map ] || { echo no; return; }
  53   while read -r line; do
  54     fields="$(echo "$line" | awk '{ print $1 " " $2 " " $3 }')"
  55     if [ "${fields}" = "0 0 4294967295" ]; then
  56       echo no;
  57       return;
  58     fi
  59     if echo "${fields}" | grep -q " 0 1$"; then
  60       echo userns-root;
  61       return;
  62     fi
  63   done < /proc/self/uid_map
  64
  65   [ "$(cat /proc/self/uid_map)" = "$(cat /proc/1/uid_map)" ] && { echo userns-root; return; }
  66   echo yes
  67 }
  68
  69 getconfigpath() {
  70   basedir="$1"
  71   q="$2"
  72
  73   digest=$(jq -c -r --arg q "$q" '.manifests[] | if .annotations."org.opencontainers.image.ref.name" == $q then .digest else empty end' < "${basedir}/index.json")
  74   if [ -z "${digest}" ]; then
  75     echo "$q not found in index.json" >&2
  76     return
  77   fi
  78
  79   # Ok we have the image config digest, now get the config from that
  80   # shellcheck disable=SC2039
  81   d=${digest:7}
  82   cdigest=$(jq -c -r '.config.digest' < "${basedir}/blobs/sha256/${d}")
  83   if [ -z "${cdigest}" ]; then
  84     echo "container config not found" >&2
  85     return
  86   fi
  87
  88   # shellcheck disable=SC2039
  89   d2=${cdigest:7}
  90   echo "${basedir}/blobs/sha256/${d2}"
  91   return
  92 }
  93
  94 # Get entrypoint from oci image. Use sh if unspecified
  95 getep() {
  96   if [ "$#" -eq 0 ]; then
  97     echo "/bin/sh"
  98     return
  99   fi
 100
 101   configpath="$1"
 102
 103   ep=$(jq -c '.config.Entrypoint[]?'< "${configpath}" | tr '\n' ' ')
 104   cmd=$(jq -c '.config.Cmd[]?'< "${configpath}" | tr '\n' ' ')
 105   if [ -z "${ep}" ]; then
 106     ep="${cmd}"
 107     if [ -z "${ep}" ]; then
 108       ep="/bin/sh"
 109     fi
 110   elif [ -n "${cmd}" ]; then
 111     ep="${ep} ${cmd}"
 112   fi
 113
 114   echo "${ep}"
 115   return
 116 }
 117
 118 # get environment from oci image.
 119 getenv() {
 120   if [ "$#" -eq 0 ]; then
 121     return
 122   fi
 123
 124   configpath="$1"
 125
 126   env=$(jq -c -r '.config.Env[]'< "${configpath}")
 127
 128   echo "${env}"
 129   return
 130 }
 131
 132 # FIXME 1: only support numerical values in the configuration file.
 133 # FIXME 2: from the OCI image spec: "If group/gid is not specified,
 134 # the default group and supplementary groups of the given user/uid in
 135 # /etc/passwd from the container are applied."
 136 getuidgid() {
 137   if [ "$#" -eq 0 ]; then
 138     echo "0 0"
 139     return
 140   fi
 141
 142   configpath="$1"
 143
 144   uidgid=$(jq -c -r '.config.User // "0:0"' < "${configpath}")
 145   # shellcheck disable=SC2039
 146   uidgid=(${uidgid//:/ })
 147
 148   printf '%d %d' "${uidgid[0]:-0}" "${uidgid[1]:-0}" 2>/dev/null || true
 149   return
 150 }
 151
 152 # get cwd from oci image.
 153 getcwd() {
 154   if [ "$#" -eq 0 ]; then
 155     echo "/"
 156     return
 157   fi
 158
 159   configpath="$1"
 160
 161   cwd=$(jq -c -r '.config.WorkingDir // "/"' < "${configpath}")
 162
 163   echo "${cwd}"
 164   return
 165 }
 166
 167 usage() {
 168   cat <<EOF
 169 LXC container template for OCI images
 170
 171 Special arguments:
 172 [ -h | --help ]: Print this help message and exit.
 173
 174 Required arguments:
 175 [ -u | --url <url> ]: The OCI image URL
 176
 177 Optional arguments:
 178 [ --username <username> ]: The username for the registry
 179 [ --password <password> ]: The password for the registry
 180
 181 LXC internal arguments (do not pass manually!):
 182 [ --name <name> ]: The container name
 183 [ --path <path> ]: The path to the container
 184 [ --rootfs <rootfs> ]: The path to the container's rootfs
 185 [ --mapped-uid <map> ]: A uid map (user namespaces)
 186 [ --mapped-gid <map> ]: A gid map (user namespaces)
 187 EOF
 188   return 0
 189 }
 190
 191 if ! options=$(getopt -o u:h -l help,url:,username:,password:,no-cache,dhcp,name:,path:,rootfs:,mapped-uid:,mapped-gid: -- "$@"); then
 192     usage
 193     exit 1
 194 fi
 195 eval set -- "$options"
 196
 197 OCI_URL=""
 198 OCI_USERNAME=
 199 OCI_PASSWORD=
 200 OCI_USE_CACHE="true"
 201 OCI_USE_DHCP="false"
 202
 203 LXC_MAPPED_GID=
 204 LXC_MAPPED_UID=
 205 LXC_NAME=
 206 LXC_PATH=
 207 LXC_ROOTFS=
 208
 209 while :; do
 210   case "$1" in
 211     -h|--help)    usage && exit 1;;
 212     -u|--url)     OCI_URL=$2; shift 2;;
 213     --username)   OCI_USERNAME=$2; shift 2;;
 214     --password)   OCI_PASSWORD=$2; shift 2;;
 215     --no-cache)   OCI_USE_CACHE="false"; shift 1;;
 216     --dhcp)       OCI_USE_DHCP="true"; shift 1;;
 217     --name)       LXC_NAME=$2; shift 2;;
 218     --path)       LXC_PATH=$2; shift 2;;
 219     --rootfs)     LXC_ROOTFS=$2; shift 2;;
 220     --mapped-uid) LXC_MAPPED_UID=$2; shift 2;;
 221     --mapped-gid) LXC_MAPPED_GID=$2; shift 2;;
 222     *)            break;;
 223   esac
 224 done
 225
 226 # Check that we have all variables we need
 227 if [ -z "$LXC_NAME" ] || [ -z "$LXC_PATH" ] || [ -z "$LXC_ROOTFS" ]; then
 228   echo "ERROR: Not running through LXC" 1>&2
 229   exit 1
 230 fi
 231
 232 if [ -z "$OCI_URL" ]; then
 233   echo "ERROR: no OCI URL given"
 234   exit 1
 235 fi
 236
 237 if [ -n "$OCI_PASSWORD" ] && [ -z "$OCI_USERNAME" ]; then
 238   echo "ERROR: password given but no username specified"
 239   exit 1
 240 fi
 241
 242 if [ "${OCI_USE_CACHE}" = "true" ]; then
 243   if ! skopeo copy --help | grep -q 'dest-shared-blob-dir'; then
 244     echo "INFO: skopeo doesn't support blob caching"
 245     OCI_USE_CACHE="false"
 246   fi
 247 fi
 248
 249 USERNS=$(in_userns)
 250
 251 if [ "$USERNS" = "yes" ]; then
 252   if [ -z "$LXC_MAPPED_UID" ] || [ "$LXC_MAPPED_UID" = "-1" ]; then
 253     echo "ERROR: In a user namespace without a map" 1>&2
 254     exit 1
 255   fi
 256 fi
 257
 258 if [ "${OCI_USE_CACHE}" = "true" ]; then
 259   if [ "$USERNS" = "yes" ]; then
 260     DOWNLOAD_BASE="${HOME}/.cache/lxc"
 261   else
 262     DOWNLOAD_BASE="${LOCALSTATEDIR}/cache/lxc"
 263   fi
 264 else
 265   DOWNLOAD_BASE=/tmp
 266 fi
 267 mkdir -p "${DOWNLOAD_BASE}"
 268
 269 # Trap all exit signals
 270 trap cleanup EXIT HUP INT TERM
 271
 272 if ! which mktemp >/dev/null 2>&1; then
 273   DOWNLOAD_TEMP="${DOWNLOAD_BASE}/lxc-oci.$$"
 274   mkdir -p "${DOWNLOAD_TEMP}"
 275 else
 276   DOWNLOAD_TEMP=$(mktemp -d -p "${DOWNLOAD_BASE}")
 277 fi
 278
 279 # Download the image
 280 # shellcheck disable=SC2039
 281 skopeo_args=("")
 282 if [ -n "$OCI_USERNAME" ]; then
 283   CREDENTIALS="${OCI_USERNAME}"
 284
 285   if [ -n "$OCI_PASSWORD" ]; then
 286     CREDENTIALS="${CREDENTIALS}:${OCI_PASSWORD}"
 287   fi
 288
 289   # shellcheck disable=SC2039
 290   skopeo_args+=(--src-creds "${CREDENTIALS}")
 291 fi
 292
 293 if [ "${OCI_USE_CACHE}" = "true" ]; then
 294   # shellcheck disable=SC2039
 295   # shellcheck disable=SC2068
 296   skopeo_args+=(--dest-shared-blob-dir "${DOWNLOAD_BASE}")
 297   # shellcheck disable=SC2039
 298   # shellcheck disable=SC2068
 299   skopeo copy ${skopeo_args[@]} "${OCI_URL}" "oci:${DOWNLOAD_TEMP}:latest"
 300   ln -s "${DOWNLOAD_BASE}/sha256" "${DOWNLOAD_TEMP}/blobs/sha256"
 301 else
 302   # shellcheck disable=SC2039
 303   # shellcheck disable=SC2068
 304   skopeo copy ${skopeo_args[@]} "${OCI_URL}" "oci:${DOWNLOAD_TEMP}:latest"
 305 fi
 306
 307 echo "Unpacking the rootfs"
 308 # shellcheck disable=SC2039
 309 umoci_args=("")
 310 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 311   # shellcheck disable=SC2039
 312   umoci_args+=(--rootless)
 313 fi
 314 # shellcheck disable=SC2039
 315 # shellcheck disable=SC2068
 316 umoci --log=error unpack ${umoci_args[@]} --image "${DOWNLOAD_TEMP}:latest" "${LXC_ROOTFS}.tmp"
 317 rmdir "${LXC_ROOTFS}"
 318 mv "${LXC_ROOTFS}.tmp/rootfs" "${LXC_ROOTFS}"
 319
 320 OCI_CONF_FILE=$(getconfigpath "${DOWNLOAD_TEMP}" latest)
 321 LXC_CONF_FILE="${LXC_PATH}/config"
 322 entrypoint=$(getep "${OCI_CONF_FILE}")
 323 echo "lxc.execute.cmd = '${entrypoint}'" >> "${LXC_CONF_FILE}"
 324 echo "lxc.mount.auto = proc:mixed sys:mixed cgroup:mixed" >> "${LXC_CONF_FILE}"
 325
 326 environment=$(getenv "${OCI_CONF_FILE}")
 327 # shellcheck disable=SC2039
 328 while read -r line; do
 329   echo "lxc.environment = ${line}" >> "${LXC_CONF_FILE}"
 330 done <<< "${environment}"
 331
 332 if [ -e "${LXC_TEMPLATE_CONFIG}/common.conf" ]; then
 333   echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/common.conf" >> "${LXC_CONF_FILE}"
 334 fi
 335
 336 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ] && [ -e "${LXC_TEMPLATE_CONFIG}/userns.conf" ]; then
 337   echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/userns.conf" >> "${LXC_CONF_FILE}"
 338 fi
 339
 340 if [ -e "${LXC_TEMPLATE_CONFIG}/oci.common.conf" ]; then
 341   echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/oci.common.conf" >> "${LXC_CONF_FILE}"
 342 fi
 343
 344 if [ "${OCI_USE_DHCP}" = "true" ]; then
 345   echo "lxc.hook.start-host = ${LXC_HOOK_DIR}/dhclient" >> "${LXC_CONF_FILE}"
 346   echo "lxc.hook.stop = ${LXC_HOOK_DIR}/dhclient" >> "${LXC_CONF_FILE}"
 347 fi
 348
 349 echo "lxc.uts.name = ${LXC_NAME}" >> "${LXC_CONF_FILE}"
 350 # set the hostname
 351 cat <<EOF > "${LXC_ROOTFS}/etc/hostname"
 352 ${LXC_NAME}
 353 EOF
 354
 355 # set minimal hosts
 356 cat <<EOF > "${LXC_ROOTFS}/etc/hosts"
 357 127.0.0.1   localhost
 358 127.0.1.1   ${LXC_NAME}
 359 ::1     localhost ip6-localhost ip6-loopback
 360 fe00::0 ip6-localnet
 361 ff00::0 ip6-mcastprefix
 362 ff02::1 ip6-allnodes
 363 ff02::2 ip6-allrouters
 364 EOF
 365
 366 # shellcheck disable=SC2039
 367 uidgid=($(getuidgid "${OCI_CONF_FILE}"))
 368 # shellcheck disable=SC2039
 369 echo "lxc.init.uid = ${uidgid[0]}" >> "${LXC_CONF_FILE}"
 370 # shellcheck disable=SC2039
 371 echo "lxc.init.gid = ${uidgid[1]}" >> "${LXC_CONF_FILE}"
 372
 373 cwd=$(getcwd "${OCI_CONF_FILE}")
 374 echo "lxc.init.cwd = ${cwd}" >> "${LXC_CONF_FILE}"
 375
 376 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 377   chown "$LXC_MAPPED_UID" "$LXC_PATH/config" "$LXC_PATH/fstab" > /dev/null 2>&1 || true
 378 fi
 379 if [ -n "$LXC_MAPPED_GID" ] && [ "$LXC_MAPPED_GID" != "-1" ]; then
 380   chgrp "$LXC_MAPPED_GID" "$LXC_PATH/config" "$LXC_PATH/fstab" > /dev/null 2>&1 || true
 381 fi
 382
 383 exit 0