Adding script to set up FlexVolume on a COS instance using mounting utility image in GCR.

cluster/gce/gci/flexvolume_node_setup.sh

+#!/bin/bash
+
+# Copyright 2017 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Sets up FlexVolume drivers on GCE COS instances using mounting utilities packaged in a Google
+# Container Registry image.
+# The user-provided FlexVolume driver(s) must be under /flexvolume of the image filesystem.
+# For example, the driver k8s/nfs must be located at /flexvolume/k8s~nfs/nfs .
+#
+# This script should be used on a clean instance, with no FlexVolume installed.
+# Should not be run on instances with an existing full or partial installation.
+# Upon failure, the script will clean up the partial installation automatically.
+#
+# Must be executed under /home/kubernetes/bin with sudo.
+# Warning: kubelet will be restarted upon successful execution.
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+MOUNTER_IMAGE=${1:-}
+MOUNTER_PATH=/home/kubernetes/flexvolume_mounter
+VOLUME_PLUGIN_DIR=/etc/srv/kubernetes/kubelet-plugins/volume/exec
+
+usage() {
+  echo "usage: $0 imagename[:tag]"
+  echo "    imagename  Name of a Container Registry image. By default the latest image is used."
+  echo "    :tag       Container Registry image tag."
+  exit 1
+}
+
+if [ -z ${MOUNTER_IMAGE} ]; then
+  echo "ERROR: No Container Registry mounter image is specified."
+  echo
+  usage
+fi
+
+# Unmounts a mount point lazily. If a mount point does not exist, continue silently,
+# and without error.
+umount_silent() {
+  umount -l $1 &> /dev/null || /bin/true
+}
+
+# Waits for kubelet to restart for 1 minute.
+kubelet_wait() {
+  timeout=60
+  kubelet_readonly_port=10255
+  until [[ $timeout -eq 0 ]]; do
+    printf "."
+    if [[ $( curl -s http://localhost:${kubelet_readonly_port}/healthz ) == "ok" ]]; then
+      return 0
+    fi
+    sleep 1
+    timeout=$(( timeout-1 ))
+  done
+
+  # Timed out waiting for kubelet to become healthy.
+  return 1
+}
+
+flex_clean() {
+  echo
+  echo "An error has occurred. Cleaning up..."
+  echo
+
+  umount_silent ${VOLUME_PLUGIN_DIR}
+  rm -rf ${VOLUME_PLUGIN_DIR}
+  umount_silent ${MOUNTER_PATH}/var/lib/kubelet
+  umount_silent ${MOUNTER_PATH}
+  rm -rf ${MOUNTER_PATH}
+  
+  if [ -n ${IMAGE_URL:-} ]; then
+    docker rmi -f ${IMAGE_URL} &> /dev/null || /bin/true
+  fi
+  if [ -n ${MOUNTER_DEFAULT_NAME:-} ]; then
+    docker rm -f ${MOUNTER_DEFAULT_NAME} &> /dev/null || /bin/true
+  fi
+}
+
+trap flex_clean ERR
+
+# Generates a bash script that wraps all calls to the actual driver inside mount utilities
+# in the chroot environment. Kubelet sees this script as the FlexVolume driver.
+generate_chroot_wrapper() {
+  if [ ! -d ${MOUNTER_PATH}/flexvolume ]; then
+    echo "Failed to set up FlexVolume driver: cannot find directory '/flexvolume' in the mount utility image."
+    exit 1
+  fi
+  
+  for driver_dir in ${MOUNTER_PATH}/flexvolume/*; do
+    if [ -d "$driver_dir" ]; then
+
+      filecount=$(ls -1 $driver_dir | wc -l)
+      if [ $filecount -gt 1 ]; then
+        echo "ERROR: Expected 1 file in the FlexVolume directory but found $filecount."
+        exit 1
+      fi
+      
+      driver_file=$( ls $driver_dir | head -n 1 )
+
+      # driver_path points to the actual driver inside the mount utility image,
+      # relative to image root.
+      # wrapper_path is the wrapper script location, which is known to kubelet.
+      driver_path=flexvolume/$( basename $driver_dir )/${driver_file}
+      wrapper_dir=${VOLUME_PLUGIN_DIR}/$( basename $driver_dir )
+      wrapper_path=${wrapper_dir}/${driver_file}
+
+      mkdir -p $wrapper_dir
+      cat >$wrapper_path <<EOF
+#!/bin/bash
+chroot ${MOUNTER_PATH} ${driver_path} "\$@"
+EOF
+
+      chmod 755 $wrapper_path
+      echo "FlexVolume driver installed at ${wrapper_path}"
+    fi
+  done
+}
+
+echo
+echo "Importing mount utility image from Container Registry..."
+echo
+
+METADATA=http://metadata.google.internal/computeMetadata/v1
+SVC_ACCT_ENDPOINT=$METADATA/instance/service-accounts/default
+ACCESS_TOKEN=$(curl -s -H 'Metadata-Flavor: Google' $SVC_ACCT_ENDPOINT/token | cut -d'"' -f 4)
+PROJECT_ID=$(curl -s -H 'Metadata-Flavor: Google' $METADATA/project/project-id)
+IMAGE_URL=gcr.io/${PROJECT_ID}/${MOUNTER_IMAGE}
+MOUNTER_DEFAULT_NAME=flexvolume_mounter
+sudo -u ${SUDO_USER} docker login -u _token -p $ACCESS_TOKEN https://gcr.io > /dev/null
+sudo -u ${SUDO_USER} docker run --name=${MOUNTER_DEFAULT_NAME} ${IMAGE_URL}
+docker export ${MOUNTER_DEFAULT_NAME} > /tmp/${MOUNTER_DEFAULT_NAME}.tar
+docker rm ${MOUNTER_DEFAULT_NAME} > /dev/null
+docker rmi ${IMAGE_URL} > /dev/null
+
+echo
+echo "Loading mount utilities onto this instance..."
+echo
+
+mkdir ${MOUNTER_PATH}
+tar xf /tmp/${MOUNTER_DEFAULT_NAME}.tar -C ${MOUNTER_PATH}
+
+# Bind the kubelet directory to one under flexvolume_mounter
+mkdir ${MOUNTER_PATH}/var/lib/kubelet
+mount --rbind /var/lib/kubelet/ ${MOUNTER_PATH}/var/lib/kubelet
+mount --make-rshared ${MOUNTER_PATH}/var/lib/kubelet
+
+# Remount the flexvolume_mounter environment with /dev enabled.
+mount --bind ${MOUNTER_PATH} ${MOUNTER_PATH}
+mount -o remount,dev,exec ${MOUNTER_PATH}
+
+echo
+echo "Setting up FlexVolume driver..."
+echo
+
+mkdir -p ${VOLUME_PLUGIN_DIR}
+mount --bind ${VOLUME_PLUGIN_DIR} ${VOLUME_PLUGIN_DIR}
+mount -o remount,exec ${VOLUME_PLUGIN_DIR}
+generate_chroot_wrapper
+
+echo
+echo "Restarting Kubelet..."
+echo
+
+systemctl restart kubelet.service
+kubelet_wait
+if [ $? -eq 0 ]; then
+  echo
+  echo "FlexVolume is ready."
+else
+  echo "ERROR: Timed out after 1 minute waiting for kubelet restart."
+fi