Arq Restore

A program to restore Arq 6 and 7 compatible backups.

I am using Arq 7 for remote backup of some important files on my Mac for many years now. The software works quite well for me, but there aren't as many updates recently as there used to be in the past. Since the data format is documented and I wanted to look into Rust, I created this project to learn the language and to also have an insurance plan in case the company behind Arq goes bust.

Installation

cargo install arq-restore

Status

The basics do work, but there are various sharp edges. Be careful if you consider relying on this!

You can currently only restore backups that are in the local file system. S3-compatible storage locations planned (maybe more with opendal). In the meantime, you can use rclone serve to mount your remote storage location as an NFS volume.

The code is not at all optimized for performance, but in my testing I was able to get close to restore speed of about 75 MB/sec, which I would consider "good enough" for now.

Arq Concepts

• Repository: Actually not a concept by Arq. arq-restore calls the storage location "repository".
• Backup Plan: Configures a backup, consisting of a storage location, one or more folders, a schedule etc
• Backup Folder: A plan can have one or more configured folders to be backed up.
• Backup Record: A backup at a specific point in time for a "Backup Folder"

Usage

Usage is definitely subject to change. Check out arq-restore --help.

All operations require to provide the encryption password for the backup. It can be provided in three ways:

• --password: directly provide (not recommended)

• --password-file: read password from file, whitespace will be truncated

• --password-command: run command and use output as password, whitespace will be truncated

  You can use this to get a password from the macOS keychain:

  arq-restore --password-command="security find-generic-password -w -s 'my-arq-backup'" […]
  

List Backup Folders, Backup Records and Files in Backup

• List backup folders

  arq-restore -PASSWORD- list --repository=arq/backup/D7E09473-74BF-4E6D-86C3-43A033570D80
  

• List backup records for given backup folder

  arq-restore -PASSWORD- list --repository=arq/backup/D7E09473-74BF-4E6D-86C3-43A033570D80 --folder=DD994AEF-F9CB-4D39-B12D-1EF5305103C8
  

• List all directories and files for this backup record and folder

  arq-restore -PASSWORD- list --repository=arq/backup/D7E09473-74BF-4E6D-86C3-43A033570D80 --folder=DD994AEF-F9CB-4D39-B12D-1EF5305103C8 --record=1763107319
  

• …which can be limited to a specific subfolder

  arq-restore -PASSWORD- list --repository=arq/backup/D7E09473-74BF-4E6D-86C3-43A033570D80 --folder=DD994AEF-F9CB-4D39-B12D-1EF5305103C8 --record=1763107319 --subtree=/path/somewhere/into/the/backup/
  

Restore

arq-restore -PASSWORD- restore --repository=arq/backup/D7E09473-74BF-4E6D-86C3-43A033570D80 --record=1763107319 --folder=DD994AEF-F9CB-4D39-B12D-1EF5305103C8 tmp/restore/path/

• if a file exists, it won't be overwritten
• file ownership, mode and extendend attributes are currently not restored

Inspect

arq-resore -PASSWORD- inspect [--raw] FILE

inspect can be used to decrypt (and parse, depending on the detected file type) various metadata files. This is mostly a debugging tool for the arq-restore development itself.

TODOs

High Level

• better error messages all around
• continue if there is an error restoring a file
  • currently, for various errors, restoring will just abort
• add support to read backup data from S3-compatible storage
• support unencrypted backups (as supported by Arq)
• add option to create a "shopping list" of files needed to actually do the restore
  • this would allow to generate a list of files needed form the remote that can be downloaded with rclone for example
  • this way arq-restore does not need to support implementing so many storage backends; also useful for a slow or unstable uplink
• add option to --exclude to exclude file name patterns from being restored

Internal

• get rid of the remaining panic! and unwraps 🫣 Revisit panic! for internal checks
• improve test coverage