**** DONE Restic Backup on Windows 10 with Babun/Cygwin                       :blog:software:windows:
CLOSED: [2018-05-31 Thu 10:12]
:PROPERTIES:
:CREATED:  [2018-05-31 Thu 09:38]
:ID:       2018-05-31-restic-cygwin
:END:
:LOGBOOK:
- State "DONE"       from "DONE"       [2019-03-13 Wed 13:51]
- State "DONE"       from              [2018-05-31 Thu 10:12]
:END:

Update 2019-03-13: comments Florian.

[[https://media.ccc.de/v/GLT18_-_378_-__-_g_ap147_005_-_201804281245_-_lightning_talks][I heard]] great things about [[https://restic.net/][restic]] for solving the backup requirement.

Since it does also support Windows, I gave it a try on my business
Windows 10 and my [[http://babun.github.io/][babun]] environment, which is a user-land [[https://en.wikipedia.org/wiki/Cygwin][Cygwin]] with
better presets.

Here are my findings.

***** Installation

I downloaded restic [[https://github.com/restic/restic/releases/][from its GitHub release page]] (v0.9.0) and
according to [[https://restic.net/#installation][the installation documentation]] I moved it to
=C:\Windows\System32\= which I found a bit odd recommendation,
modifying the sub-hierarchy of Windows system files. So far, I moved
files to a directory which is part of the PATH environment variable.
This time, I followed the instructions strictly.

The [[https://restic.readthedocs.io/en/stable/020_installation.html#autocompletion][bash/zsh autocompletion setup]] did not work on my babun-zsh and I
did not invest time to debug this issue. I guess it relates to not
knowing where to store the resulting file.

***** Setting up a New Repository

As far as I understood the documentation, restic follows some ideas of
[[https://git-scm.com/][Git]]. It is chunk-based, identifies files with hashes (renaming and
moving files do not result in additional backup effort), de-duplicates
files, and uses so called repositories to store backups. Further more,
it seems to be the case that restic is able to store backups from
multiple locations in one single repository. Very cool: repository
encryption is built-in right from the start.

And this is where I had to get creative: there is [[https://restic.readthedocs.io/en/stable/030_preparing_a_new_repo.html#password-prompt-on-windows][a known issue with
the password prompt on Windows]]. I could have installed a thing called
winpty (I don't know so far). However, I chose to try a different
approach: storing a long passphrase in a text file and use the
=--password-file= command line option.

And it worked: without the =--password-file= option, restic was
stuck without any error or warning message. With the option, restic
was able to initialize the repository:

: export PWFILE=path/to/keyfile
: restic init --repo "T:\restic-backup" --password-file $PWFILE

As you might notice, restic on Cygwin needs Windows-style paths.
Cygwin usually uses paths like =/cygdrive/t/restic-backup/= but restic
does not accept them or handles them in a wrong way. You have to use
Windows-style paths, not being able to use shell completion for paths.

***** Backup

My first backup was easily done:

: restic -r "T:\restic-backup" --verbose backup \
:   "C:\Users\karl.voit\data" --password-file $PWFILE

Yes, it's true: restic is fast.

The same command runs an update on the backup and a new snapshot is
created.

***** Curating Backups

List all snapshots of a repository is done like:

: restic -r "T:\restic-backup" snapshots --password-file $PWFILE

Something that worries me a bit is the necessity of the recommendation
to periodically check the integrity of a backup. This can be done
with:

: restic -r "T:\restic-backup" check --password-file $PWFILE

***** Restore

Restoring a single file is easy:

: restic -r "T:\restic-backup" restore latest \
:   --target C:\Users\karl.voit\restore-test \
:   --include "relative\path\file.txt" \
:   --password-file $PWFILE

I found out that using absolute paths for =--include= did not work:
restic returned with no error or visible result. So please do use
relative paths for include or exclude statements.

***** Summary

It was nice to see that restic is a clever backup solution with
built-in encryption that even works on Cygwin-like environments.

There are some drawbacks such as the missing path completion on
Cygwin/zsh and some trial and error around using absolute or relative
path names for this and that.

I am not sure why the manual mentions the necessity of periodically
checking the integrity of repositories. This might indicate issues
where restic corrupts repositories or this might just indicate the
possibility of errors introduced by external things.

I am not using restic for the time being.
This is not related to restic itself but other circumstances in our
Windows environment.

However, it is good to know that there is something out there which
might replace my hand-crafted rsync-scripts some day.

***** Comments
:PROPERTIES:
:END:

Florian wrote me that he did not face any issue with the password
prompt on Windows 10 with Restic 0.9.4 and PowerShell ISE.

Related to "periodically checking the integrity of repositories",
Florian thinks that this refers to other people modifying the
repository like deleting a file or losing data by [[https://en.wikipedia.org/wiki/Soft_error][bit-flips]] on the
storage media.