Goal

You have docker volume on one host and want to move that volume to another host. For example, you want to transfer PostgreSQL container with it's volume to another host.

Solution

Actually, there is no in-a-box solution from Docker, so we need to:

• attach our volume to another container
• copy and archive all files
• copy archive to another host
• create volume

Script

To be honest, original script was posted on Medium, by @funkyfisch. Original gist - https://gist.github.com/funkyfisch/0372475f82639cbba0fbc55df7eff648#file-migrate-docker-volume-sh.

#!/bin/bash

# Environment check

SOURCE_HOST_ADDRESS=localhost
SOURCE_HOST_USER=$USER
TARGET_HOST_ADDRESS=192.168.126.168
TARGET_HOST_USER=targetuser

# If migrating from localhost, set this to localhost
if [[ ! $SOURCE_HOST_ADDRESS ]]
then
  echo "Please set the current host address in SOURCE_HOST_ADDRESS"
  exit 1
fi

# If migrating from localhost, set this to $USER
if [[ ! $SOURCE_HOST_USER ]]
then
  echo "Please set the current host user in SOURCE_HOST"
  exit 1
fi

# If migrating to localhost, set this to localhost
if [[ ! $TARGET_HOST_ADDRESS ]]
then
  echo "Please set the new host address in TARGET_HOST_ADDRESS"
  exit 1
fi

# If migrating to localhost, set this to $USER
if [[ ! $TARGET_HOST_USER ]]
then
  echo "Please set the new host user in TARGET_HOST_USER"
  exit 1
fi

# Argument check

if [[ ! $1 ]]
then
  echo "Please supply a docker volume name, as displayed by the command 'docker volume ls'"
  exit 1
fi
volume_name=$1

# Export the volume from the current instance

echo "Exporting volume $volume_name on $SOURCE_HOST_ADDRESS"
ssh "$SOURCE_HOST_USER"@"$SOURCE_HOST_ADDRESS" "\
mkdir -p \$HOME/docker-volume-backup
docker run \
  --rm \
  -v $volume_name:/volume-backup-source \
  -v \$HOME/docker-volume-backup:/volume-backup-target \
  busybox \
  sh -c 'cd /volume-backup-source && tar cf /volume-backup-target/backup.tar .' \
"


# Transfer the exported volume to the new address

echo "Transferring exported volume $volume_name from $SOURCE_HOST_ADDRESS to $TARGET_HOST_ADDRESS"
ssh "$TARGET_HOST_USER"@"$TARGET_HOST_ADDRESS" "mkdir -p \$HOME/docker-volume-backup"
scp -3 "$SOURCE_HOST_USER"@"$SOURCE_HOST_ADDRESS":./docker-volume-backup/backup.tar \
  "$TARGET_HOST_USER"@"$TARGET_HOST_ADDRESS":./docker-volume-backup/backup.tar


# Restore the backup

echo "Creating volume $volume_name on $TARGET_HOST_ADDRESS"
ssh "$TARGET_HOST_USER"@"$TARGET_HOST_ADDRESS" "\
docker volume create $volume_name \
&& docker run \
  --rm \
  -v $volume_name:/volume-backup-target \
  -v \$HOME/docker-volume-backup/:/volume-backup-source \
  busybox \
  sh -c 'cd /volume-backup-target && tar xf /volume-backup-source/backup.tar .' \
"

# Clean up residual files

echo "Cleaning up unnecessary files"
ssh "$SOURCE_HOST_USER"@"$SOURCE_HOST_ADDRESS" "rm -rf \$HOME/docker-volume-backup"
ssh "$TARGET_HOST_USER"@"$TARGET_HOST_ADDRESS" "rm -rf \$HOME/docker-volume-backup"

echo "Successfully migrated docker volume $volume_name from $SOURCE_HOST_ADDRESS to $TARGET_HOST_ADDRESS"

Run

./script.sh sentry-postgres