ZFS snapshot to Backblaze B2 rclone remote backup script. Work in progress code snapshot from self-hosted infrastructure development.

backup.sh

#!/bin/bash

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# Make sure running as root.
if [ "$(id -u)" != "0" ]; then
  echo "This script must be run as root." 1>&2
  exit 1
fi

# Set the working directory to the directory of the script.
# https://stackoverflow.com/a/3355423/2612383
cd "$(dirname "$0")" || exit

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# Set rclone configuration file path.
RCLONE_CONFIG_FILE="./rclone.conf"

# The number of file transfers to run in parallel.
# https://rclone.org/docs/#transfers-n
# https://rclone.org/b2/
# https://www.backblaze.com/blog/increasing-thread-count-useful-in-sheets-and-cloud-storage-speed/
RCLONE_PARALLEL_TRANSFERS=32

# Set rclone base sync command with config flag.
# https://rclone.org/docs/
# https://rclone.org/flags/
# https://rclone.org/commands/rclone_sync/
RCLONE_CMD="rclone --config $RCLONE_CONFIG_FILE sync"

# Set rclone base sync flags.
# https://rclone.org/crypt/
# https://rclone.org/flags/
RCLONE_SYNC_FLAGS="--copy-links --fast-list --transfers $RCLONE_PARALLEL_TRANSFERS"

# Define rclone sync function.
# Example usage:
# `rclone_sync "/path/to/source" "remote:/path/to/destination" "--filter-from filter-file"`
# or without optional flags
# `rclone_sync "/path/to/source" "remote:/path/to/destination"`
rclone_sync() {
    # Set source and destination paths.
    SOURCE_PATH="$1"
    DESTINATION_PATH="$2"

    # Set optional rclone sync flags.
    # https://rclone.org/filtering/
    RCLONE_SYNC_FLAGS_OPTIONAL="$3"

    # Create an array to hold the command and its flags.
    RCLONE_CMD_ARRAY=($RCLONE_CMD $RCLONE_SYNC_FLAGS)

    # Append optional flags if provided.
    if [ -n "$RCLONE_SYNC_FLAGS_OPTIONAL" ]; then
        RCLONE_CMD_ARRAY+=($RCLONE_SYNC_FLAGS_OPTIONAL)
    fi

    # Append source and destination paths.
    RCLONE_CMD_ARRAY+=("$SOURCE_PATH" "$DESTINATION_PATH")

    # Run the rclone sync command.
    "${RCLONE_CMD_ARRAY[@]}"

    # Check if the rclone command was successful.
    if [ $? -eq 0 ]; then
        echo "Rclone sync nominal for $SOURCE_PATH to $DESTINATION_PATH."
    else
        echo "Rclone sync failed for $SOURCE_PATH to $DESTINATION_PATH." 1>&2
    fi
}

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# Set ZFS snapshot read-only mount root directory.
SNAPSHOT_MOUNT_ROOT="/mnt/cloud_backup_snapshots"

# ZFS snapshot prefix.
SNAPSHOT_PREFIX="service_cloud_backup"

# ZFS snapshot creation function.
create_zfs_snapshot() {
    # The ZFS dataset path to snapshot.
    DATASET_PATH="$1"

    # Remove the leading slash from the dataset path, if present.
    DATASET_PATH="${DATASET_PATH#/}"

    # Generate a timestamp to uniquely identify the snapshot.
    TIMESTAMP=$(date +"%Y%m%d%H%M%S")

    # Construct the snapshot name using the dataset path and timestamp.
    SNAPSHOT_NAME="${DATASET_PATH}@${SNAPSHOT_PREFIX}_${TIMESTAMP}"

    # Create the ZFS snapshot.
    zfs snapshot "$SNAPSHOT_NAME"
    if [ $? -ne 0 ]; then
        echo "Failed to create ZFS snapshot for $DATASET_PATH" 1>&2
        return 1
    fi

    echo "$SNAPSHOT_NAME"
}

# ZFS snapshot read-only mount function.
mount_zfs_snapshot() {
    # The name of the snapshot to mount.
    SNAPSHOT_NAME="$1"

    # Construct the mount path using the snapshot name, replacing '@' with '/'.
    MOUNT_PATH="${SNAPSHOT_MOUNT_ROOT}/$(echo "$SNAPSHOT_NAME" | tr '@' '/')"

    # Create the mount directory.
    mkdir -p "$MOUNT_PATH"
    if [ $? -ne 0 ]; then
        echo "Failed to create mount directory $MOUNT_PATH" 1>&2
        return 1
    fi

    # Mount the ZFS snapshot as read-only.
    mount -t zfs -o ro "$SNAPSHOT_NAME" "$MOUNT_PATH"
    if [ $? -ne 0 ]; then
        echo "Failed to mount ZFS snapshot $SNAPSHOT_NAME to $MOUNT_PATH" 1>&2
        return 1
    fi

    echo "$MOUNT_PATH"
}

# ZFS cleanup function.
# Unmount ZFS snapshot, remove nested mount directory, and destroy snapshots with the ZFS snapshot prefix.
zfs_cleanup() {
    # The mount path to unmount.
    MOUNT_PATH="$1"
    # The ZFS dataset path to snapshot.
    DATASET_PATH="$2"

    # Unmount the ZFS snapshot.
    umount "$MOUNT_PATH"
    if [ $? -ne 0 ]; then
        echo "Failed to unmount $MOUNT_PATH" 1>&2
        return 1
    fi

    # Remove the leading slash from the dataset path, if present.
    DATASET_PATH="${DATASET_PATH#/}"

    # Identify the first directory in the dataset path.
    DATASET_FIRST_DIR=$(echo "$DATASET_PATH" | cut -d'/' -f1)

    # Construct the path to the root mount directory.
    MOUNT_PATH_ROOT="${SNAPSHOT_MOUNT_ROOT}/${DATASET_FIRST_DIR}"

    # Remove the nested mount directory.
    rm -rf "$MOUNT_PATH_ROOT"
    if [ $? -ne 0 ]; then
        echo "Failed to remove mount directory $MOUNT_PATH_ROOT" 1>&2
        return 1
    fi

    # Check if there are any snapshots to delete.
    SNAPSHOTS=$(zfs list -H -t snapshot -o name -r "$DATASET_PATH" | grep "@$SNAPSHOT_PREFIX")
    if [ -n "$SNAPSHOTS" ]; then
        # Destroy snapshots with the ZFS snapshot prefix for the specific dataset path.
        echo "$SNAPSHOTS" | xargs -n 1 zfs destroy -r
        if [ $? -ne 0 ]; then
            echo "Failed to destroy ZFS snapshots with prefix $SNAPSHOT_PREFIX for dataset $DATASET_PATH" 1>&2
            return 1
        fi
    else
        echo "No snapshots found with prefix $SNAPSHOT_PREFIX for dataset $DATASET_PATH" 1>&2
    fi
}

# Example usage of the above functions:
# ```
# DATASET_PATH="/path/to/dataset"
# DEST_PATH="my-service:/"

# SNAPSHOT_NAME=$(create_zfs_snapshot "$DATASET_PATH")
# if [ $? -eq 0 ]; then
#     MOUNT_PATH=$(mount_zfs_snapshot "$SNAPSHOT_NAME")
#     if [ $? -eq 0 ]; then
#         rclone_sync "$MOUNT_PATH" "$DEST_PATH"
#         zfs_cleanup "$MOUNT_PATH" "$DATASET_PATH"
#     fi
# fi
# ```
# Where `my-service` is the name of the rclone remote as defined in the rclone.conf file.

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# Backup "/tank/b2_backup_test" to "test-remote" rclone remote.
DATASET_PATH="/tank/b2_backup_test"
DEST_PATH="test-remote:/"

SNAPSHOT_NAME=$(create_zfs_snapshot "$DATASET_PATH")
if [ $? -eq 0 ]; then
    MOUNT_PATH=$(mount_zfs_snapshot "$SNAPSHOT_NAME")
    if [ $? -eq 0 ]; then
        rclone_sync "$MOUNT_PATH" "$DEST_PATH"
        zfs_cleanup "$MOUNT_PATH" "$DATASET_PATH"
    fi
fi

cloud_backup.service

[Unit]
Description=Service for Cloud Backup using ZFS snapshots and rclone
After=network.target

[Service]
Type=oneshot
ExecStart=/opt/cloud_backup_service/backup.sh
User=root
Group=root

cloud_backup.timer

[Unit]
Description=Timer for Cloud Backup Service

[Timer]
OnCalendar=00:15
AccuracySec=15m
RandomizedDelaySec=15m
Persistent=true

[Install]
WantedBy=timers.target