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 # check var is decimal.
 133 isdecimal() {
 134   var="$1"
 135   if [ "${var}" -eq "${var}" ] 2> /dev/null; then
 136     return 0
 137   else
 138     return 1
 139   fi
 140 }
 141
 142 # get uid, gid from oci image.
 143 getuidgid() {
 144   configpath="$1"
 145   rootpath="$2"
 146   passwdpath="${rootpath}/etc/passwd"
 147   grouppath="${rootpath}/etc/group"
 148
 149   usergroup=$(jq -c -r '.config.User' < "${configpath}")
 150   # shellcheck disable=SC2039
 151   usergroup=(${usergroup//:/ })
 152
 153   user=${usergroup[0]:-0}
 154   if ! isdecimal "${user}"; then
 155     if [ -f ${passwdpath} ]; then
 156       user=$(grep "^${user}:" "${passwdpath}" | awk -F: '{print $3}')
 157     else
 158       user=0
 159     fi
 160   fi
 161
 162   group=${usergroup[1]:-}
 163   if [ -z "${group}" ]; then
 164     if [ -f "${passwdpath}" ]; then
 165       group=$(grep "^[^:]*:[^:]*:${user}:" "${passwdpath}" | awk -F: '{print $4}')
 166     else
 167       group=0
 168     fi
 169   elif ! isdecimal "${group}"; then
 170     if [ -f "${grouppath}" ]; then
 171       group=$(grep "^${group}:" "${grouppath}" | awk -F: '{print $3}')
 172     else
 173       group=0
 174     fi
 175   fi
 176
 177   echo "${user:-0} ${group:-0}"
 178   return
 179 }
 180
 181 # get cwd from oci image.
 182 getcwd() {
 183   if [ "$#" -eq 0 ]; then
 184     echo "/"
 185     return
 186   fi
 187
 188   configpath="$1"
 189
 190   cwd=$(jq -c -r '.config.WorkingDir // "/"' < "${configpath}")
 191
 192   echo "${cwd}"
 193   return
 194 }
 195
 196 usage() {
 197   cat <<EOF
 198 LXC container template for OCI images
 199
 200 Special arguments:
 201 [ -h | --help ]: Print this help message and exit.
 202
 203 Required arguments:
 204 [ -u | --url <url> ]: The OCI image URL
 205
 206 Optional arguments:
 207 [ --username <username> ]: The username for the registry
 208 [ --password <password> ]: The password for the registry
 209
 210 LXC internal arguments (do not pass manually!):
 211 [ --name <name> ]: The container name
 212 [ --path <path> ]: The path to the container
 213 [ --rootfs <rootfs> ]: The path to the container's rootfs
 214 [ --mapped-uid <map> ]: A uid map (user namespaces)
 215 [ --mapped-gid <map> ]: A gid map (user namespaces)
 216 EOF
 217   return 0
 218 }
 219
 220 if ! options=$(getopt -o u:h -l help,url:,username:,password:,no-cache,dhcp,name:,path:,rootfs:,mapped-uid:,mapped-gid: -- "$@"); then
 221     usage
 222     exit 1
 223 fi
 224 eval set -- "$options"
 225
 226 OCI_URL=""
 227 OCI_USERNAME=
 228 OCI_PASSWORD=
 229 OCI_USE_CACHE="true"
 230 OCI_USE_DHCP="false"
 231
 232 LXC_MAPPED_GID=
 233 LXC_MAPPED_UID=
 234 LXC_NAME=
 235 LXC_PATH=
 236 LXC_ROOTFS=
 237
 238 while :; do
 239   case "$1" in
 240     -h|--help)    usage && exit 1;;
 241     -u|--url)     OCI_URL=$2; shift 2;;
 242     --username)   OCI_USERNAME=$2; shift 2;;
 243     --password)   OCI_PASSWORD=$2; shift 2;;
 244     --no-cache)   OCI_USE_CACHE="false"; shift 1;;
 245     --dhcp)       OCI_USE_DHCP="true"; shift 1;;
 246     --name)       LXC_NAME=$2; shift 2;;
 247     --path)       LXC_PATH=$2; shift 2;;
 248     --rootfs)     LXC_ROOTFS=$2; shift 2;;
 249     --mapped-uid) LXC_MAPPED_UID=$2; shift 2;;
 250     --mapped-gid) LXC_MAPPED_GID=$2; shift 2;;
 251     *)            break;;
 252   esac
 253 done
 254
 255 # Check that we have all variables we need
 256 if [ -z "$LXC_NAME" ] || [ -z "$LXC_PATH" ] || [ -z "$LXC_ROOTFS" ]; then
 257   echo "ERROR: Not running through LXC" 1>&2
 258   exit 1
 259 fi
 260
 261 if [ -z "$OCI_URL" ]; then
 262   echo "ERROR: no OCI URL given"
 263   exit 1
 264 fi
 265
 266 if [ -n "$OCI_PASSWORD" ] && [ -z "$OCI_USERNAME" ]; then
 267   echo "ERROR: password given but no username specified"
 268   exit 1
 269 fi
 270
 271 if [ "${OCI_USE_CACHE}" = "true" ]; then
 272   if ! skopeo copy --help | grep -q 'dest-shared-blob-dir'; then
 273     echo "INFO: skopeo doesn't support blob caching"
 274     OCI_USE_CACHE="false"
 275   fi
 276 fi
 277
 278 USERNS=$(in_userns)
 279
 280 if [ "$USERNS" = "yes" ]; then
 281   if [ -z "$LXC_MAPPED_UID" ] || [ "$LXC_MAPPED_UID" = "-1" ]; then
 282     echo "ERROR: In a user namespace without a map" 1>&2
 283     exit 1
 284   fi
 285 fi
 286
 287 if [ "${OCI_USE_CACHE}" = "true" ]; then
 288   if [ "$USERNS" = "yes" ]; then
 289     DOWNLOAD_BASE="${HOME}/.cache/lxc"
 290   else
 291     DOWNLOAD_BASE="${LOCALSTATEDIR}/cache/lxc"
 292   fi
 293 else
 294   DOWNLOAD_BASE=/tmp
 295 fi
 296 mkdir -p "${DOWNLOAD_BASE}"
 297
 298 # Trap all exit signals
 299 trap cleanup EXIT HUP INT TERM
 300
 301 if ! which mktemp >/dev/null 2>&1; then
 302   DOWNLOAD_TEMP="${DOWNLOAD_BASE}/lxc-oci.$$"
 303   mkdir -p "${DOWNLOAD_TEMP}"
 304 else
 305   DOWNLOAD_TEMP=$(mktemp -d -p "${DOWNLOAD_BASE}")
 306 fi
 307
 308 # Download the image
 309 # shellcheck disable=SC2039
 310 skopeo_args=("")
 311 if [ -n "$OCI_USERNAME" ]; then
 312   CREDENTIALS="${OCI_USERNAME}"
 313
 314   if [ -n "$OCI_PASSWORD" ]; then
 315     CREDENTIALS="${CREDENTIALS}:${OCI_PASSWORD}"
 316   fi
 317
 318   # shellcheck disable=SC2039
 319   skopeo_args+=(--src-creds "${CREDENTIALS}")
 320 fi
 321
 322 if [ "${OCI_USE_CACHE}" = "true" ]; then
 323   # shellcheck disable=SC2039
 324   # shellcheck disable=SC2068
 325   skopeo_args+=(--dest-shared-blob-dir "${DOWNLOAD_BASE}")
 326   # shellcheck disable=SC2039
 327   # shellcheck disable=SC2068
 328   skopeo copy ${skopeo_args[@]} "${OCI_URL}" "oci:${DOWNLOAD_TEMP}:latest"
 329   ln -s "${DOWNLOAD_BASE}/sha256" "${DOWNLOAD_TEMP}/blobs/sha256"
 330 else
 331   # shellcheck disable=SC2039
 332   # shellcheck disable=SC2068
 333   skopeo copy ${skopeo_args[@]} "${OCI_URL}" "oci:${DOWNLOAD_TEMP}:latest"
 334 fi
 335
 336 echo "Unpacking the rootfs"
 337 # shellcheck disable=SC2039
 338 umoci_args=("")
 339 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 340   # shellcheck disable=SC2039
 341   umoci_args+=(--rootless)
 342 fi
 343 # shellcheck disable=SC2039
 344 # shellcheck disable=SC2068
 345 umoci --log=error unpack ${umoci_args[@]} --image "${DOWNLOAD_TEMP}:latest" "${LXC_ROOTFS}.tmp"
 346 rmdir "${LXC_ROOTFS}"
 347 mv "${LXC_ROOTFS}.tmp/rootfs" "${LXC_ROOTFS}"
 348
 349 OCI_CONF_FILE=$(getconfigpath "${DOWNLOAD_TEMP}" latest)
 350 LXC_CONF_FILE="${LXC_PATH}/config"
 351 entrypoint=$(getep "${OCI_CONF_FILE}")
 352 echo "lxc.execute.cmd = '${entrypoint}'" >> "${LXC_CONF_FILE}"
 353 echo "lxc.mount.auto = proc:mixed sys:mixed cgroup:mixed" >> "${LXC_CONF_FILE}"
 354
 355 environment=$(getenv "${OCI_CONF_FILE}")
 356 # shellcheck disable=SC2039
 357 while read -r line; do
 358   echo "lxc.environment = ${line}" >> "${LXC_CONF_FILE}"
 359 done <<< "${environment}"
 360
 361 if [ -e "${LXC_TEMPLATE_CONFIG}/common.conf" ]; then
 362   echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/common.conf" >> "${LXC_CONF_FILE}"
 363 fi
 364
 365 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ] && [ -e "${LXC_TEMPLATE_CONFIG}/userns.conf" ]; then
 366   echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/userns.conf" >> "${LXC_CONF_FILE}"
 367 fi
 368
 369 if [ -e "${LXC_TEMPLATE_CONFIG}/oci.common.conf" ]; then
 370   echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/oci.common.conf" >> "${LXC_CONF_FILE}"
 371 fi
 372
 373 if [ "${OCI_USE_DHCP}" = "true" ]; then
 374   echo "lxc.hook.start-host = ${LXC_HOOK_DIR}/dhclient" >> "${LXC_CONF_FILE}"
 375   echo "lxc.hook.stop = ${LXC_HOOK_DIR}/dhclient" >> "${LXC_CONF_FILE}"
 376 fi
 377
 378 echo "lxc.uts.name = ${LXC_NAME}" >> "${LXC_CONF_FILE}"
 379 # set the hostname
 380 cat <<EOF > "${LXC_ROOTFS}/etc/hostname"
 381 ${LXC_NAME}
 382 EOF
 383
 384 # set minimal hosts
 385 cat <<EOF > "${LXC_ROOTFS}/etc/hosts"
 386 127.0.0.1   localhost
 387 127.0.1.1   ${LXC_NAME}
 388 ::1     localhost ip6-localhost ip6-loopback
 389 fe00::0 ip6-localnet
 390 ff00::0 ip6-mcastprefix
 391 ff02::1 ip6-allnodes
 392 ff02::2 ip6-allrouters
 393 EOF
 394
 395 # shellcheck disable=SC2039
 396 uidgid=($(getuidgid "${OCI_CONF_FILE}" "${LXC_ROOTFS}" ))
 397 # shellcheck disable=SC2039
 398 echo "lxc.init.uid = ${uidgid[0]}" >> "${LXC_CONF_FILE}"
 399 # shellcheck disable=SC2039
 400 echo "lxc.init.gid = ${uidgid[1]}" >> "${LXC_CONF_FILE}"
 401
 402 cwd=$(getcwd "${OCI_CONF_FILE}")
 403 echo "lxc.init.cwd = ${cwd}" >> "${LXC_CONF_FILE}"
 404
 405 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 406   chown "$LXC_MAPPED_UID" "$LXC_PATH/config" "$LXC_PATH/fstab" > /dev/null 2>&1 || true
 407 fi
 408 if [ -n "$LXC_MAPPED_GID" ] && [ "$LXC_MAPPED_GID" != "-1" ]; then
 409   chgrp "$LXC_MAPPED_GID" "$LXC_PATH/config" "$LXC_PATH/fstab" > /dev/null 2>&1 || true
 410 fi
 411
 412 exit 0