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