[bug#69513] [PATCH] services: Add restic-backup service.

[Ludovic Courtès]

Hi,

Giacomo Leidi <goodoldpaul@autistici.org> skribis:

> * gnu/services/backup.scm: New file.
> * gnu/local.mk: Add this.
> * doc/guix.texi: Document this.
>
> Change-Id: I9efd5559bb445b484107a7c27c2d0a65ccad1e66

[...]

> +@subsubheading Backup services

Please capitalize headings: “Backup Services”.

We should probably move documentation of ‘syncthing-service-type’ here,
even if they live in different modules for now.

> +The @code{(gnu services backup)} module offers services for backing up
> +file system trees. For now, it provides the 
> @code{restic-backup-service-type}.
                    ^
Nitpick: Please leave two spaces after an end-of-sentence period (for
easier Emacs navigation, readability, and consistency).

> +To backup a list of file system trees to a pre-initialized, end-to-end
> +encrypted, deduplicated data repository, you could so with the
> +@code{restic-backup-service-type}. For example with the following
> +configuration:

How about:

  With @code{restic-backup-service-type}, you can periodically back up
  directories and files with @uref{https://restic.net/, Restic}, which
  supports end-to-end encryption and deduplication.  Consider the
  following configuration:

?

> +Each @code{restic-backup-job} translates to an mcron job which sets the
> +@code{RESTIC_PASSWORD} environment variable by reading the first line of

@env{RESTIC_PASSWORD}

> +@item @code{specification} (type: gexp-or-string)
> +A string or a gexp that will be passed as time specification in the
> +mcron job specification (@pxref{Syntax, mcron job specifications,,
> +mcron,GNU@tie{}mcron}).

Maybe ‘schedule’ rather than ‘specification’, to clarify what’s being
specified?  (That’s the name I chose in <unattended-upgrade-configuration>.)

> +@item @code{included} (default: @code{'()}) (type: list-of-lowerables)
> +A list of values that are lowered to strings representing filesystem
> +paths.  These are the paths that will be recursively included in the
> +current job.

In GNU and Guix, “path” is used to denote “search paths”; in other
cases, we write “file name” or “file”.  So I’d suggest something like:

  The list of files or directories to be backed up.

The ‘files-to-backup’ (or ‘files’?) may be more descriptive that
‘included’.

> +  (password-file
> +   (string)
> +   "The path of a password file, readable by the configured @code{user}, that

“Name of the password file”

> +will be used to set the @code{RESTIC_PASSWORD} environment variable for the

s/@code/@env/

> +    (program-file
> +     "restic-backup-job.scm"
> +     (with-imported-modules (source-module-closure
> +                             '((guix build utils)))
> +       #~(begin
> +           (use-modules (guix build utils)
> +                        (ice-9 popen)
> +                        (ice-9 rdelim))
> +           (setenv "RESTIC_PASSWORD"
> +                   (with-input-from-file #$password-file read-line))
> +
> +           (execlp #$restic #$@verbose
> +                   "-r" #$repository
> +                   #$@extra-flags
> +                   "backup" #$@included))))))

I believe (guix build utils) is unused, in which case you can remove it.

The ‘execlp’ call lacks argv[0]; it should look like this:

  (execlp #$restic #$restic #$@verbose "-r" …)

(Notice that #$restic appears twice.)

Could you send an updated patch?

Thanks,
Ludo’.