add export volume script

docker_export_volume.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+
+# Author: Alexey Ukhov <alex@ukhov.ru>
+
+SCRIPTSRC=`readlink -f "$0" || echo "$0"`
+SCRIPT_PATH=`dirname "$SCRIPTSRC" || echo .`
+
+#First check if the user provided all needed arguments
+if [ "$1" = "" ]
+then
+        echo "Please provide a source volume name"
+        exit
+fi
+
+#Check if the source volume name does exist
+docker volume inspect $1 > /dev/null 2>&1
+if [ "$?" != "0" ]
+then
+        echo "The source volume \"$1\" does not exist"
+        exit
+fi
+
+BACKUP_FOLDER=${2:-backup}
+if [ ! -d "${BACKUP_FOLDER}" ]
+then
+        echo "Create backup folder '${BACKUP_FOLDER}'"
+        mkdir -p ${BACKUP_FOLDER}
+fi
+
+NOW=$(date +"%Y-%m-%d-%H-%M-%S")
+BACKUP_FILE=${BACKUP_FOLDER}/$1_${NOW}.tar.gz
+
+echo "Export volume '$1' into file '${BACKUP_FILE}'"
+docker run --rm -v $1:/from alpine ash -c 'cd /from && tar -cOzf - .' > ${BACKUP_FILE}