[bug#74961] [PATCH] scripts: deploy: Add the expression command line flag.

[Richard Sent <richard@freakingpenguin.com>]

* guix/scripts/deploy.scm (show-help): Add help.
(%options): Add -e and --expression.
(guix-deploy): Use expression and check for invalid flag combinations.

Change-Id: I200c9ff0c9a8c686efff4a21cd33c10429f3c73e
---

Submitting a patch to take care of https://issues.guix.gnu.org/71841.
Always struck me as odd that deploy doesn't have a --evaluate flag
like many others, so here's a go at it.

I didn't update documentation because "invoking guix deploy" still has
a TODO stating

> @c FIXME/TODO: Separate the API doc from the CLI doc.

As is there doesn't seem to be a good place to insert --expression
documentation without sidetracking the info page.

This'll be useful for me at least as I store my machine list in a
channel.

 guix/scripts/deploy.scm | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/guix/scripts/deploy.scm b/guix/scripts/deploy.scm
index 4b1a603049..941ee199f0 100644
--- a/guix/scripts/deploy.scm
+++ b/guix/scripts/deploy.scm
@@ -2,6 +2,7 @@
 ;;; Copyright © 2019 David Thompson <davet@gnu.org>
 ;;; Copyright © 2019 Jakob L. Kreuze <zerodaysfordays@sdf.org>
 ;;; Copyright © 2020-2022 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2024 Richard Sent <richard@freakingpenguin.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -59,6 +60,9 @@ (define (show-help)
   -V, --version          display version information and exit"))
   (newline)
   (display (G_ "
+  -e, --expression=EXPR  deploy the list of machines EXPR evaluates to"))
+  (newline)
+  (display (G_ "
   -x, --execute          execute the following command on all the machines"))
   (newline)
   (display (G_ "
@@ -74,6 +78,9 @@ (define %options
                  (lambda args
                    (show-version-and-exit "guix deploy")))
 
+         (option '(#\e "expression") #t #f
+                 (lambda (opt name arg result)
+                   (alist-cons 'expression arg result)))
          (option '(#\n "dry-run") #f #f
                  (lambda (opt name arg result)
                    (alist-cons 'dry-run? #t result)))
@@ -247,10 +254,16 @@ (define-command (guix-deploy . args)
            (opts (parse-command-line args %options (list %default-options)
                                      #:argument-handler handle-argument))
            (file (assq-ref opts 'file))
-           (machines (and file (load-source-file file)))
+           (expression (assoc-ref opts 'expression))
+           (machines (or (and file (load-source-file file))
+                         (and expression (read/eval expression))))
            (dry-run? (assoc-ref opts 'dry-run?))
            (execute-command? (assoc-ref opts 'execute-command?)))
-      (unless file
+      (when (and file expression)
+        (leave (G_ "both '--expression' and a deployment file were provided~%")))
+
+      (unless (or file
+                  expression)
         (leave (G_ "missing deployment file argument~%")))
 
       (when (and (pair? command) (not execute-command?))

base-commit: 1a62f687e504c67f26693f3bc60a90e503ab4ea9
-- 
2.46.0