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