Creates an extra Docker volume and mounts it to /va/lib/docker

create-docker-volume.sh

#!/bin/bash

# Check disksize with `parted /dev/sda print` before

STARTING_SIZE=$1
DISK_SIZE=$2
RESTART_DOCKER=false

if [ -z "${STARTING_SIZE}" ]; then
  echo "Please enter the starting size in GB from where the new partition should be created"

  parted /dev/sda print
  
  exit 1
fi

if [ -z "${DISK_SIZE}" ]; then
  echo "Please enter the total size of the disk /dev/sda in GB as argument"

  parted /dev/sda print

  exit 1
fi

echo "Creating new Docker volume starting from ${STARTING_SIZE}GB to ${DISK_SIZE}GB"

parted /dev/sda mkpart extended ${STARTING_SIZE}GB ${DISK_SIZE}GB
parted /dev/sda mkpart logical ${STARTING_SIZE}GB ${DISK_SIZE}GB

vgextend host-vg /dev/sda5

lvcreate --name docker --extents 100%FREE host-vg
mkfs.ext4 /dev/host-vg/docker -N 6500000

if [ -d "/var/lib/docker" ]; then
  echo "Stop service Docker and move all folders and files under /var/lib/docker to the new volume"
  mount /dev/mapper/host--vg-docker /mnt

  systemctl stop docker

  echo "Now move all files from /var/lib/docker to /mnt. This could take a while, be patient..."
  cp -rp /var/lib/docker/* /mnt/ && rm /var/lib/docker/* -rf
  exit_status=$?
  if [ $exit_status -ne 0 ]; then
    echo "Copying data to the new volume failed, please check why. Script will stop now..."
    exit 1
  fi

  umount /mnt
  RESTART_DOCKER=true
fi

mkdir -p /var/lib/docker

echo "/dev/mapper/host--vg-docker /var/lib/docker ext4 defaults 0 2" >> /etc/fstab

echo "Now the new volume will be mounted as /var/lib/docker"
mount -a

if [ $RESTART_DOCKER ]; then
  echo "Restarting service Docker..."
  systemctl start docker
  systemctl status docker
fi