bindMountDockerData.sh

#!/bin/sh
# Author: Nicolas Schneider
# Mounts all volumes that are mounted in a Docker container
# under a given root relative to their mount point in the container.
# Usage: bindMountDockerData.sh container /mnt/path
# 
# Example: Docker container 'demo' which has a volume mounted at /somedata and
#          another at /home/userdata.
# Running 'bindMountDockerData.sh demo /mnt/dockerdemo'
# will result in:
#     /mnt/dockerdemo/somedata      -> all data from '/somedata'
#     /mnt/dockerdemo/home/userdata -> all data from '/home/userdata'

container=$1
mountPath=$2

# Check that we are run as root.
if [[ $(/usr/bin/id -u) -ne 0 ]]; then
    echo "$0 must be run as root"
    exit 1
fi

# Retrieve all mounted directories for a given docker container.
# This will output a newline delimited list of host-dir:container-dir pairs.
mountPoints=`docker inspect --format='{{range $mount := .Mounts}}{{$mount.Source}}:{{$mount.Destination}}{{"\n"}}{{end}}' "$container"`

# Set the field separator to new line
IFS=$'\n'
# Loop through the mount points
for mount in $mountPoints
do
    # split the mount point at the ':'
    IFS=\: read -a directories <<< "$mount"
    hostDir=${directories[0]}
    mountDir=${mountPath}${directories[1]}

    # mount the directory
    mkdir -p "$mountDir"
    mount --bind "$hostDir" "$mountDir"
done