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 ! command -v $bin >/dev/null 2>&1; then
  31     echo "ERROR: Missing required tool: $bin" 1>&2
  32     exit 1
  33   fi
  34 done
  35
  36 LOCALSTATEDIR=@LOCALSTATEDIR@
  37 LXC_TEMPLATE_CONFIG=@LXCTEMPLATECONFIG@
  38 LXC_HOOK_DIR=@LXCHOOKDIR@
  39 MOUNT_HELPER="atomfs"
  40 MOUNTED_WORKDIR=""
  41
  42 # Some useful functions
  43 cleanup() {
  44   if [ -d "${LXC_ROOTFS}.tmp" ]; then
  45     rm -Rf "${LXC_ROOTFS}.tmp"
  46   fi
  47   if [ -n "${MOUNTED_WORKDIR}" ]; then
  48     echo "${MOUNT_HELPER} unmount ${MOUNTED_WORKDIR}" >&2
  49     "${MOUNT_HELPER}" umount "${MOUNTED_WORKDIR}"
  50     MOUNTED_WORKDIR=""
  51   fi
  52 }
  53
  54 in_userns() {
  55   [ -e /proc/self/uid_map ] || { echo no; return; }
  56   while read -r line; do
  57     fields="$(echo "$line" | awk '{ print $1 " " $2 " " $3 }')"
  58     if [ "${fields}" = "0 0 4294967295" ]; then
  59       echo no;
  60       return;
  61     fi
  62     if echo "${fields}" | grep -q " 0 1$"; then
  63       echo userns-root;
  64       return;
  65     fi
  66   done < /proc/self/uid_map
  67
  68   if [ -e /proc/1/uid_map ]; then
  69     if [ "$(cat /proc/self/uid_map)" = "$(cat /proc/1/uid_map)" ]; then
  70       echo userns-root
  71       return
  72     fi
  73   fi
  74   echo yes
  75 }
  76
  77 getconfigpath() {
  78   local basedir="$1" mfpath="$2" cdigest=""
  79   # Ok we have the image config digest, now get the config ref from the manifest.
  80   # shellcheck disable=SC2039
  81   cdigest=$(jq -c -r '.config.digest' < "$mfpath")
  82   if [ -z "${cdigest}" ]; then
  83     echo "container config not found" >&2
  84     return
  85   fi
  86
  87   # cdigest is '<hashtype>:<hash>', so 'ht' gets type, hv gets value.
  88   local ht="${cdigest%%:*}" hv="${cdigest#*:}" p=""
  89   p="$basedir/blobs/$ht/$hv"
  90   if [ ! -f "$p" ]; then
  91     echo "config file did not exist for digest $cdigest" >&2
  92     return 1
  93   fi
  94   echo "$p"
  95 }
  96
  97 getmanifestpath() {
  98   local basedir="$1" ref="$2" p=""
  99   # if given 'sha256:<hash>' then return the blobs/sha256/hash
 100   case "$ref" in
 101     sha256:*)
 102       p="$basedir/blobs/sha256/${ref#sha256:}"
 103       [ -f "$p" ] && echo "$p" && return 0
 104       echo "could not find manifest path to blob $ref. file did not exist: $p" >&2
 105       return 1
 106       ;;
 107   esac
 108   # find the reference by annotation
 109   local blobref="" hashtype="" hashval=""
 110   blobref=$(jq -c -r --arg q "$ref" '.manifests[] | if .annotations."org.opencontainers.image.ref.name" == $q then .digest else empty end' < "${basedir}/index.json")
 111   # blobref is 'hashtype:hash'
 112   hashtype="${blobref%%:*}"
 113   hashval="${blobref#*:}"
 114   p="$basedir/blobs/$hashtype/$hashval"
 115   [ -f "$p" ] && echo "$p" && return 0
 116   echo "did not find manifest for $ref. file did not exist: $p" >&2
 117   return 1
 118 }
 119
 120 getlayermediatype() {
 121   jq -c -r '.layers[0].mediaType' <"$1"
 122 }
 123
 124 # Get entrypoint from oci image. Use sh if unspecified
 125 getep() {
 126   if [ "$#" -eq 0 ]; then
 127     echo "/bin/sh"
 128     return
 129   fi
 130
 131   configpath="$1"
 132
 133   ep=$(jq -c '.config.Entrypoint[]?'< "${configpath}" | tr '\n' ' ')
 134   cmd=$(jq -c '.config.Cmd[]?'< "${configpath}" | tr '\n' ' ')
 135   if [ -z "${ep}" ]; then
 136     ep="${cmd}"
 137     if [ -z "${ep}" ]; then
 138       ep="/bin/sh"
 139     fi
 140   elif [ -n "${cmd}" ]; then
 141     ep="${ep} ${cmd}"
 142   fi
 143
 144   echo "${ep}"
 145   return
 146 }
 147
 148 # get environment from oci image.
 149 getenv() {
 150   if [ "$#" -eq 0 ]; then
 151     return
 152   fi
 153
 154   configpath="$1"
 155
 156   env=$(jq -c -r '.config.Env[]'< "${configpath}")
 157
 158   echo "${env}"
 159   return
 160 }
 161
 162 # check var is decimal.
 163 isdecimal() {
 164   var="$1"
 165   if [ "${var}" -eq "${var}" ] 2> /dev/null; then
 166     return 0
 167   else
 168     return 1
 169   fi
 170 }
 171
 172 # get uid, gid from oci image.
 173 getuidgid() {
 174   configpath="$1"
 175   rootpath="$2"
 176   passwdpath="${rootpath}/etc/passwd"
 177   grouppath="${rootpath}/etc/group"
 178
 179   usergroup=$(jq -c -r '.config.User' < "${configpath}")
 180   # shellcheck disable=SC2039
 181   usergroup=(${usergroup//:/ })
 182
 183   user=${usergroup[0]:-0}
 184   if ! isdecimal "${user}"; then
 185     if [ -f ${passwdpath} ]; then
 186       user=$(grep "^${user}:" "${passwdpath}" | awk -F: '{print $3}')
 187     else
 188       user=0
 189     fi
 190   fi
 191
 192   group=${usergroup[1]:-}
 193   if [ -z "${group}" ]; then
 194     if [ -f "${passwdpath}" ]; then
 195       group=$(grep "^[^:]*:[^:]*:${user}:" "${passwdpath}" | awk -F: '{print $4}')
 196     else
 197       group=0
 198     fi
 199   elif ! isdecimal "${group}"; then
 200     if [ -f "${grouppath}" ]; then
 201       group=$(grep "^${group}:" "${grouppath}" | awk -F: '{print $3}')
 202     else
 203       group=0
 204     fi
 205   fi
 206
 207   echo "${user:-0} ${group:-0}"
 208   return
 209 }
 210
 211 # get cwd from oci image.
 212 getcwd() {
 213   if [ "$#" -eq 0 ]; then
 214     echo "/"
 215     return
 216   fi
 217
 218   configpath="$1"
 219
 220   cwd=$(jq -c -r '.config.WorkingDir // "/"' < "${configpath}")
 221
 222   echo "${cwd}"
 223   return
 224 }
 225
 226 usage() {
 227   cat <<EOF
 228 LXC container template for OCI images
 229
 230 Special arguments:
 231 [ -h | --help ]: Print this help message and exit.
 232
 233 Required arguments:
 234 [ -u | --url <url> ]: The OCI image URL
 235
 236 Optional arguments:
 237 [ --username <username> ]: The username for the registry
 238 [ --password <password> ]: The password for the registry
 239 [ --mount-helper <command> ]: program that will be used to mount. default is 'atomfs'
 240
 241      mount-helper is expected to support being called with 'mount'
 242      and 'umount' subcommands as below:
 243
 244         mount-helper mount oci:<oci_dir>:<oci_name> <mountpoint>
 245         mount-helper umount <mountpoint>
 246
 247 LXC internal arguments (do not pass manually!):
 248 [ --name <name> ]: The container name
 249 [ --path <path> ]: The path to the container
 250 [ --rootfs <rootfs> ]: The path to the container's rootfs
 251 [ --mapped-uid <map> ]: A uid map (user namespaces)
 252 [ --mapped-gid <map> ]: A gid map (user namespaces)
 253 EOF
 254   return 0
 255 }
 256
 257 if ! options=$(getopt -o u:h -l help,url:,username:,password:,no-cache,dhcp,name:,path:,rootfs:,mapped-uid:,mapped-gid:,mount-helper: -- "$@"); then
 258     usage
 259     exit 1
 260 fi
 261 eval set -- "$options"
 262
 263 OCI_URL=""
 264 OCI_USERNAME=
 265 OCI_PASSWORD=
 266 OCI_USE_CACHE="true"
 267 OCI_USE_DHCP="false"
 268
 269 LXC_MAPPED_GID=
 270 LXC_MAPPED_UID=
 271 LXC_NAME=
 272 LXC_PATH=
 273 LXC_ROOTFS=
 274
 275 while :; do
 276   case "$1" in
 277     -h|--help)    usage && exit 1;;
 278     -u|--url)     OCI_URL=$2; shift 2;;
 279     --username)   OCI_USERNAME=$2; shift 2;;
 280     --password)   OCI_PASSWORD=$2; shift 2;;
 281     --no-cache)   OCI_USE_CACHE="false"; shift 1;;
 282     --dhcp)       OCI_USE_DHCP="true"; shift 1;;
 283     --name)       LXC_NAME=$2; shift 2;;
 284     --path)       LXC_PATH=$2; shift 2;;
 285     --rootfs)     LXC_ROOTFS=$2; shift 2;;
 286     --mapped-uid) LXC_MAPPED_UID=$2; shift 2;;
 287     --mapped-gid) LXC_MAPPED_GID=$2; shift 2;;
 288     --mount-helper) MOUNT_HELPER=$2; shift 2;;
 289     *)            break;;
 290   esac
 291 done
 292
 293 # Check that we have all variables we need
 294 if [ -z "$LXC_NAME" ] || [ -z "$LXC_PATH" ] || [ -z "$LXC_ROOTFS" ]; then
 295   echo "ERROR: Not running through LXC" 1>&2
 296   exit 1
 297 fi
 298
 299 if [ -z "$OCI_URL" ]; then
 300   echo "ERROR: no OCI URL given"
 301   exit 1
 302 fi
 303
 304 if [ -n "$OCI_PASSWORD" ] && [ -z "$OCI_USERNAME" ]; then
 305   echo "ERROR: password given but no username specified"
 306   exit 1
 307 fi
 308
 309 if [ "${OCI_USE_CACHE}" = "true" ]; then
 310   if ! skopeo copy --help | grep -q 'dest-shared-blob-dir'; then
 311     echo "INFO: skopeo doesn't support blob caching"
 312     OCI_USE_CACHE="false"
 313   fi
 314 fi
 315
 316 USERNS=$(in_userns)
 317
 318 if [ "$USERNS" = "yes" ]; then
 319   if [ -z "$LXC_MAPPED_UID" ] || [ "$LXC_MAPPED_UID" = "-1" ]; then
 320     echo "ERROR: In a user namespace without a map" 1>&2
 321     exit 1
 322   fi
 323 fi
 324
 325 OCI_DIR="$LXC_PATH/oci"
 326 if [ "${OCI_USE_CACHE}" = "true" ]; then
 327   if [ "$USERNS" = "yes" ]; then
 328     DOWNLOAD_BASE="${HOME}/.cache/lxc"
 329   else
 330     DOWNLOAD_BASE="${LOCALSTATEDIR}/cache/lxc"
 331   fi
 332 else
 333   DOWNLOAD_BASE="$OCI_DIR"
 334 fi
 335 mkdir -p "${DOWNLOAD_BASE}"
 336
 337 # Trap all exit signals
 338 trap cleanup EXIT HUP INT TERM
 339
 340 # Download the image
 341 # shellcheck disable=SC2039
 342 skopeo_args=("--remove-signatures" "--insecure-policy")
 343 if [ -n "$OCI_USERNAME" ]; then
 344   CREDENTIALS="${OCI_USERNAME}"
 345
 346   if [ -n "$OCI_PASSWORD" ]; then
 347     CREDENTIALS="${CREDENTIALS}:${OCI_PASSWORD}"
 348   fi
 349
 350   # shellcheck disable=SC2039
 351   skopeo_args+=(--src-creds "${CREDENTIALS}")
 352 fi
 353
 354 OCI_NAME="$LXC_NAME"
 355 if [ "${OCI_USE_CACHE}" = "true" ]; then
 356   skopeo_args+=(--dest-shared-blob-dir "${DOWNLOAD_BASE}")
 357   mkdir -p "${OCI_DIR}/blobs/"
 358   ln -s "${DOWNLOAD_BASE}/sha256" "${OCI_DIR}/blobs/sha256"
 359 fi
 360
 361 skopeo copy "${skopeo_args[@]}" "${OCI_URL}" "oci:${OCI_DIR}:${OCI_NAME}"
 362
 363 mfpath=$(getmanifestpath "${OCI_DIR}" "${OCI_NAME}")
 364 OCI_CONF_FILE=$(getconfigpath "${OCI_DIR}" "$mfpath")
 365 mediatype=$(getlayermediatype "$mfpath")
 366 echo "mfpath=$mfpath conf=$OCI_CONF_FILE" 1>&2
 367 echo "mediatype=$mediatype" >&2
 368
 369 case "$mediatype" in
 370   #application/vnd.oci.image.layer.v1.tar+gzip
 371   application/vnd.oci.image.layer.v1.tar*)
 372     echo "Unpacking tar rootfs" 2>&1
 373     # shellcheck disable=SC2039
 374     umoci_args=("")
 375     if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 376       # shellcheck disable=SC2039
 377       umoci_args+=(--rootless)
 378     fi
 379     # shellcheck disable=SC2039
 380     # shellcheck disable=SC2068
 381     umoci --log=error unpack ${umoci_args[@]} --image "${OCI_DIR}:${OCI_NAME}" "${LXC_ROOTFS}.tmp"
 382     find "${LXC_ROOTFS}.tmp/rootfs" -mindepth 1 -maxdepth 1 -exec mv '{}' "${LXC_ROOTFS}/" \;
 383     ;;
 384   #application/vnd.stacker.image.layer.squashfs+zstd+verity
 385   application/vnd.*.image.layer.squashfs*)
 386     if ! command -v "${MOUNT_HELPER}" >/dev/null 2>&1; then
 387       echo "media type $mediatype requires $MOUNT_HELPER" >&2
 388       exit 1
 389     fi
 390     echo "$MOUNT_HELPER mount ${OCI_DIR}:${OCI_NAME} $LXC_ROOTFS" >&2
 391     "$MOUNT_HELPER" mount "${OCI_DIR}:${OCI_NAME}" "$LXC_ROOTFS"
 392     MOUNTED_WORKDIR="$LXC_ROOTFS"
 393     ;;
 394   *)
 395     echo "Unknown media type $mediatype" >&2
 396     exit 1
 397     ;;
 398 esac
 399
 400 LXC_CONF_FILE="${LXC_PATH}/config"
 401 entrypoint=$(getep "${OCI_CONF_FILE}")
 402 echo "lxc.execute.cmd = '${entrypoint}'" >> "${LXC_CONF_FILE}"
 403 echo "lxc.mount.auto = proc:mixed sys:mixed cgroup:mixed" >> "${LXC_CONF_FILE}"
 404
 405 case "$mediatype" in
 406   application/vnd.*.image.layer.squashfs*)
 407     echo "lxc.hook.version = 1" >> "${LXC_CONF_FILE}"
 408     # shellcheck disable=SC2016
 409     echo "lxc.hook.pre-mount = $MOUNT_HELPER mount" \
 410         '${LXC_ROOTFS_PATH}/../oci:${LXC_NAME} ${LXC_ROOTFS_PATH}' \
 411         >> "${LXC_CONF_FILE}";;
 412 esac
 413
 414 environment=$(getenv "${OCI_CONF_FILE}")
 415 # shellcheck disable=SC2039
 416 while read -r line; do
 417   echo "lxc.environment = ${line}" >> "${LXC_CONF_FILE}"
 418 done <<< "${environment}"
 419
 420 if [ -e "${LXC_TEMPLATE_CONFIG}/common.conf" ]; then
 421   echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/common.conf" >> "${LXC_CONF_FILE}"
 422 fi
 423
 424 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ] && [ -e "${LXC_TEMPLATE_CONFIG}/userns.conf" ]; then
 425   echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/userns.conf" >> "${LXC_CONF_FILE}"
 426 fi
 427
 428 if [ -e "${LXC_TEMPLATE_CONFIG}/oci.common.conf" ]; then
 429   echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/oci.common.conf" >> "${LXC_CONF_FILE}"
 430 fi
 431
 432 if [ "${OCI_USE_DHCP}" = "true" ]; then
 433   echo "lxc.hook.start-host = ${LXC_HOOK_DIR}/dhclient" >> "${LXC_CONF_FILE}"
 434   echo "lxc.hook.stop = ${LXC_HOOK_DIR}/dhclient" >> "${LXC_CONF_FILE}"
 435 fi
 436
 437 echo "lxc.uts.name = ${LXC_NAME}" >> "${LXC_CONF_FILE}"
 438 # set the hostname
 439 cat <<EOF > "${LXC_ROOTFS}/etc/hostname"
 440 ${LXC_NAME}
 441 EOF
 442
 443 # set minimal hosts
 444 cat <<EOF > "${LXC_ROOTFS}/etc/hosts"
 445 127.0.0.1   localhost
 446 127.0.1.1   ${LXC_NAME}
 447 ::1     localhost ip6-localhost ip6-loopback
 448 fe00::0 ip6-localnet
 449 ff00::0 ip6-mcastprefix
 450 ff02::1 ip6-allnodes
 451 ff02::2 ip6-allrouters
 452 EOF
 453
 454 # shellcheck disable=SC2039
 455 uidgid=($(getuidgid "${OCI_CONF_FILE}" "${LXC_ROOTFS}" ))
 456 # shellcheck disable=SC2039
 457 echo "lxc.init.uid = ${uidgid[0]}" >> "${LXC_CONF_FILE}"
 458 # shellcheck disable=SC2039
 459 echo "lxc.init.gid = ${uidgid[1]}" >> "${LXC_CONF_FILE}"
 460
 461 cwd=$(getcwd "${OCI_CONF_FILE}")
 462 echo "lxc.init.cwd = ${cwd}" >> "${LXC_CONF_FILE}"
 463
 464 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 465   chown "$LXC_MAPPED_UID" "$LXC_PATH/config" "$LXC_PATH/fstab" > /dev/null 2>&1 || true
 466 fi
 467 if [ -n "$LXC_MAPPED_GID" ] && [ "$LXC_MAPPED_GID" != "-1" ]; then
 468   chgrp "$LXC_MAPPED_GID" "$LXC_PATH/config" "$LXC_PATH/fstab" > /dev/null 2>&1 || true
 469 fi
 470
 471 exit 0