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} ${uidgid[1]:-0} 2>/dev/null || true
 140         return
 141 }
 142
 143 usage() {
 144     cat <<EOF
 145 LXC container template for OCI images
 146
 147 Special arguments:
 148 [ -h | --help ]: Print this help message and exit.
 149
 150 Required arguments:
 151 [ -u | --url <url> ]: The OCI image URL
 152
 153 Optional arguments:
 154 [ --username <username> ]: The username for the registry
 155 [ --password <password> ]: The password for the registry
 156
 157 LXC internal arguments (do not pass manually!):
 158 [ --name <name> ]: The container name
 159 [ --path <path> ]: The path to the container
 160 [ --rootfs <rootfs> ]: The path to the container's rootfs
 161 [ --mapped-uid <map> ]: A uid map (user namespaces)
 162 [ --mapped-gid <map> ]: A gid map (user namespaces)
 163
 164 EOF
 165     return 0
 166 }
 167
 168 options=$(getopt -o u:h -l help,url:,username:,password:,no-cache,\
 169 name:,path:,rootfs:,mapped-uid:,mapped-gid: -- "$@")
 170
 171 if [ $? -ne 0 ]; then
 172     usage
 173     exit 1
 174 fi
 175 eval set -- "$options"
 176
 177 OCI_URL=""
 178 OCI_USERNAME=
 179 OCI_PASSWORD=
 180 OCI_USE_CACHE="true"
 181
 182 LXC_MAPPED_GID=
 183 LXC_MAPPED_UID=
 184 LXC_NAME=
 185 LXC_PATH=
 186 LXC_ROOTFS=
 187
 188 while :; do
 189     case "$1" in
 190         -h|--help)          usage && exit 1;;
 191         -u|--url)           OCI_URL=$2; shift 2;;
 192         --username)         OCI_USERNAME=$2; shift 2;;
 193         --password)         OCI_PASSWORD=$2; shift 2;;
 194         --no-cache)         OCI_USE_CACHE="false"; shift 1;;
 195         --name)             LXC_NAME=$2; shift 2;;
 196         --path)             LXC_PATH=$2; shift 2;;
 197         --rootfs)           LXC_ROOTFS=$2; shift 2;;
 198         --mapped-uid)       LXC_MAPPED_UID=$2; shift 2;;
 199         --mapped-gid)       LXC_MAPPED_GID=$2; shift 2;;
 200         *)                  break;;
 201     esac
 202 done
 203
 204 # Check that we have all variables we need
 205 if [ -z "$LXC_NAME" ] || [ -z "$LXC_PATH" ] || [ -z "$LXC_ROOTFS" ]; then
 206     echo "ERROR: Not running through LXC." 1>&2
 207     exit 1
 208 fi
 209
 210 if [ -z "$OCI_URL" ]; then
 211     echo "ERROR: no OCI URL given"
 212     exit 1
 213 fi
 214
 215 if [ -n "$OCI_PASSWORD" ] && [ -z "$OCI_USERNAME" ]; then
 216     echo "ERROR: password given but no username specified"
 217     exit 1
 218 fi
 219
 220 if [ "${OCI_USE_CACHE}" = "true" ]; then
 221     if ! skopeo copy --help | grep -q 'dest-shared-blob-dir'; then
 222         echo "INFO: skopeo doesn't support blob caching"
 223         OCI_USE_CACHE="false"
 224     fi
 225 fi
 226
 227 USERNS=$(in_userns)
 228
 229 if [ "$USERNS" = "yes" ]; then
 230     if [ -z "$LXC_MAPPED_UID" ] || [ "$LXC_MAPPED_UID" = "-1" ]; then
 231         echo "ERROR: In a user namespace without a map." 1>&2
 232         exit 1
 233     fi
 234 fi
 235
 236 if [ "${OCI_USE_CACHE}" = "true" ]; then
 237     if [ "$USERNS" = "yes" ]; then
 238         DOWNLOAD_BASE="${HOME}/.cache/lxc"
 239     else
 240         DOWNLOAD_BASE="${LOCALSTATEDIR}/cache/lxc"
 241     fi
 242 else
 243     DOWNLOAD_BASE=/tmp
 244 fi
 245
 246 # Trap all exit signals
 247 trap cleanup EXIT HUP INT TERM
 248
 249 if ! type mktemp >/dev/null 2>&1; then
 250     DOWNLOAD_TEMP="${DOWNLOAD_BASE}/lxc-oci.$$"
 251     mkdir -p $DOWNLOAD_TEMP
 252 else
 253     DOWNLOAD_TEMP=$(mktemp -d -p "${DOWNLOAD_BASE}")
 254 fi
 255
 256 # Download the image
 257 skopeo_args=("")
 258 if [ -n "$OCI_USERNAME" ]; then
 259     CREDENTIALS="${OCI_USERNAME}"
 260     if [ -n "$OCI_PASSWORD" ]; then
 261         CREDENTIALS="${CREDENTIALS}:${OCI_PASSWORD}"
 262     fi
 263     skopeo_args+=(--src-creds "${CREDENTIALS}")
 264 fi
 265 if [ "${OCI_USE_CACHE}" = "true" ]; then
 266     skopeo_args+=(--dest-shared-blob-dir "${DOWNLOAD_BASE}")
 267     skopeo copy ${skopeo_args[@]} "${OCI_URL}" "oci:${DOWNLOAD_TEMP}:latest"
 268     ln -s "${DOWNLOAD_BASE}/sha256" "${DOWNLOAD_TEMP}/blobs/sha256"
 269 else
 270     skopeo copy ${skopeo_args[@]} "${OCI_URL}" "oci:${DOWNLOAD_TEMP}:latest"
 271 fi
 272
 273 echo "Unpacking the rootfs"
 274 umoci_args=("")
 275 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 276     umoci_args+=(--rootless)
 277 fi
 278 umoci unpack ${umoci_args[@]} --image "${DOWNLOAD_TEMP}:latest" "${LXC_ROOTFS}.tmp"
 279 rmdir "${LXC_ROOTFS}"
 280 mv "${LXC_ROOTFS}.tmp/rootfs" "${LXC_ROOTFS}"
 281
 282 OCI_CONF_FILE=$(getconfigpath ${DOWNLOAD_TEMP} latest)
 283 LXC_CONF_FILE="${LXC_PATH}/config"
 284 entrypoint=$(getep ${OCI_CONF_FILE})
 285 echo "lxc.execute.cmd = '${entrypoint}'" >> "${LXC_CONF_FILE}"
 286 echo "lxc.mount.auto = proc:mixed sys:mixed cgroup:mixed" >> "${LXC_CONF_FILE}"
 287
 288 environment=$(getenv ${OCI_CONF_FILE})
 289 while read -r line; do
 290     echo "lxc.environment = ${line}" >> "${LXC_CONF_FILE}"
 291 done <<< "${environment}"
 292
 293 if [ -e "${LXC_TEMPLATE_CONFIG}/common.conf" ]; then
 294     echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/common.conf" >> "${LXC_CONF_FILE}"
 295 fi
 296
 297 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ] && [ -e "${LXC_TEMPLATE_CONFIG}/userns.conf" ]; then
 298     echo "lxc.include = ${LXC_TEMPLATE_CONFIG}/userns.conf" >> "${LXC_CONF_FILE}"
 299 fi
 300
 301 echo "lxc.uts.name = ${LXC_NAME}" >> "${LXC_CONF_FILE}"
 302 # set the hostname
 303 cat <<EOF > ${LXC_ROOTFS}/etc/hostname
 304 ${LXC_NAME}
 305 EOF
 306
 307 # set minimal hosts
 308 cat <<EOF > ${LXC_ROOTFS}/etc/hosts
 309 127.0.0.1   localhost
 310 127.0.1.1   ${LXC_NAME}
 311 EOF
 312
 313 uidgid=($(getuidgid ${OCI_CONF_FILE}))
 314 echo "lxc.init.uid = ${uidgid[0]}" >> "${LXC_CONF_FILE}"
 315 echo "lxc.init.gid = ${uidgid[1]}" >> "${LXC_CONF_FILE}"
 316
 317 if [ -n "$LXC_MAPPED_UID" ] && [ "$LXC_MAPPED_UID" != "-1" ]; then
 318     chown $LXC_MAPPED_UID $LXC_PATH/config $LXC_PATH/fstab >/dev/null 2>&1 || true
 319 fi
 320 if [ -n "$LXC_MAPPED_GID" ] && [ "$LXC_MAPPED_GID" != "-1" ]; then
 321     chgrp $LXC_MAPPED_GID $LXC_PATH/config $LXC_PATH/fstab >/dev/null 2>&1 || true
 322 fi
 323
 324 exit 0