migrate volumes from inside wsl to docker desktop on windows..

migrate_volumes.sh

#!/usr/bin/env bash
set -euo pipefail

SRC_VOLUMES_DIR="${SRC_VOLUMES_DIR:-/var/lib/docker/volumes}"
WORK_DIR="${WORK_DIR:-/tmp/volume-migrate}"
ALPINE_IMAGE="${ALPINE_IMAGE:-alpine:3.20}"

# Skip internal docker volume dirs and anything you don't want
SKIP_NAMES_REGEX='^(backingFsBlockDev|metadata\.db|tmp|builder|buildx|containerd|overlay2|aufs|btrfs|zfs|fuse-overlayfs)$'

log() { printf "\n[%s] %s\n" "$(date +'%F %T')" "$*"; }

need_root_for_src() {
  if [[ $EUID -ne 0 ]]; then
    log "ERROR: run as root (or via sudo) so we can read $SRC_VOLUMES_DIR"
    exit 1
  fi
}

ensure_docker_cli() {
  if ! command -v docker >/dev/null 2>&1; then
    log "ERROR: docker CLI not found in PATH."
    exit 1
  fi
  # We want to be talking to Docker Desktop engine
  local name
  name="$(docker info --format '{{.Name}}' 2>/dev/null || true)"
  if [[ -z "$name" ]]; then
    log "ERROR: docker daemon not reachable from this shell."
    exit 1
  fi
  log "docker engine: $name"
}

migrate_one() {
  local vol="$1"
  local src_data="${SRC_VOLUMES_DIR}/${vol}/_data"
  local tarball="${WORK_DIR}/${vol}.tar"

  if [[ ! -d "$src_data" ]]; then
    log "SKIP (no _data): $vol"
    return 0
  fi

  if [[ "$vol" =~ $SKIP_NAMES_REGEX ]]; then
    log "SKIP (internal): $vol"
    return 0
  fi

  log "Migrating: $vol"

  # Create tarball from old data
  rm -f "$tarball"
  tar -C "$src_data" -cf "$tarball" .

  # Create volume in Docker Desktop if it doesn't exist
  if ! docker volume inspect "$vol" >/dev/null 2>&1; then
    docker volume create "$vol" >/dev/null
  fi

  # Restore into Docker Desktop volume (wipe destination first to avoid duplicates)
  docker run --rm \
    -v "${vol}:/to" \
    -v "${WORK_DIR}:/from:ro" \
    "$ALPINE_IMAGE" sh -c "rm -rf /to/* /to/.[!.]* /to/..?* 2>/dev/null || true; cd /to && tar -xf /from/${vol}.tar"

  log "Done: $vol"
}

main() {
  need_root_for_src
  ensure_docker_cli

  mkdir -p "$WORK_DIR"

  log "Source volumes dir: $SRC_VOLUMES_DIR"
  log "Work dir: $WORK_DIR"
  log "Enumerating volumes..."

  local vols=()
  while IFS= read -r name; do
    vols+=("$name")
  done < <(find "$SRC_VOLUMES_DIR" -mindepth 1 -maxdepth 1 -type d -printf '%f\n' | sort)

  log "Found ${#vols[@]} volume dirs. Starting migration..."

  local ok=0
  local fail=0

  for v in "${vols[@]}"; do
    if migrate_one "$v"; then
      ok=$((ok+1))
    else
      log "FAILED: $v"
      fail=$((fail+1))
    fi
  done

  log "Migration finished. OK=$ok FAIL=$fail"
  log "Tarballs left in: $WORK_DIR (delete when you're satisfied)."
  log "Next: verify your compose stacks with Docker Desktop volumes, then you can delete $SRC_VOLUMES_DIR to reclaim space."
}

main "$@"