Add raspi-build script for reference.

That script is deployed in a VM maintained by DEBAMAX, initially building
and publishing raspi_4_bookworm.img.xz(.sha256) every Monday below:

  https://pirogue.apt.debamax.com/raspi-images/

raspberrypi/misc/raspi-build

@@ -0,0 +1,122 @@
+#!/usr/bin/python3
+"""
+Helper to build Raspberry Pi images.
+
+The PiRogue image generation tool would ideally use daily auto-built images
+provided by Debian (https://raspi.debian.net/) but the build process might be
+stalled for several weeks or months, so we're building our own image(s) in
+a weekly fashion. This makes sure we don't end up shipping PiRogue images
+containing severely outdated packages (meaning a possibly significant amount of
+missing security/stability fixes).
+
+This script is a wrapper around image-specs's Makefile, and it also helps
+maintain the required associated sudo rules.
+
+Generate sudo configuration for the specified image(s):
+
+    ./raspi-build --sudo raspi_4_bookworm
+
+Build, compress, checksum, and rsync the specified images(s) to a web server
+(see RSYNC_DEST):
+
+    ./raspi-build --build raspi_4_bookworm
+"""
+
+import argparse
+import hashlib
+import logging
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+# Settings:
+WORK_DIR = Path('~/image-specs').expanduser()
+RSYNC_DEST = 'website:pirogue.apt.debamax.com/raspi-images/'
+
+
+def sudo(images):
+    """
+    Generate the sudo snippet for all specified images.
+    """
+    print(f'# Generated by {Path(__file__).resolve()}')
+    for image in images:
+        # Keep in sync with the Makefile in image-specs:
+        print(f'{login} ALL=NOPASSWD: /usr/bin/vmdb2 --verbose --rootfs-tarball={image}.tar.gz '
+              f'--output={image}.img {image}.yaml --log {image}.log')
+        # Keep in sync with root-owned products/byproducts (also noting the
+        # escaped ':' character):
+        print(f'{login} ALL=NOPASSWD: /usr/bin/chown {uid}\\:{gid} {WORK_DIR}/{image}.img')
+        print(f'{login} ALL=NOPASSWD: /usr/bin/chown {uid}\\:{gid} {WORK_DIR}/{image}.tar.gz')
+
+
+def run(title, *cmd):
+    """
+    Log and exec.
+    """
+    logging.info(title)
+    subprocess.check_call(*cmd)
+
+
+def build(images):
+    """
+    Build all specified images.
+    """
+    os.chdir(WORK_DIR)
+    for image in images:
+        logging.info('=== BEGIN: WORK WITH %s ===', image)
+        # Generate the uncompressed images, then fix permissions on our own:
+        run('Generate image',
+            ['make', f'{image}.img'])
+        run('Fix image owner',
+            ['sudo', 'chown', f'{uid}:{gid}', f'{WORK_DIR}/{image}.img'])
+        run('Fix tarball owner',
+            ['sudo', 'chown', f'{uid}:{gid}', f'{WORK_DIR}/{image}.tar.gz'])
+
+        # Generate compressed image ourselves to avoid timestamp-related fun if
+        # we were using the Makefile:
+        run('Compress image',
+            ['xz', '-9', f'{image}.img'])
+
+        # Compute checksum ourselves (same reason as above), without using
+        # run(): sha256sum doesn't take an output argument so we'd need
+        # shell=True.
+        logging.info('Generate checksum')
+        sha256 = hashlib.file_digest(Path(f'{image}.img.xz').open('rb'), 'sha256')
+        Path(f'{image}.img.xz.sha256').write_text(f'{sha256.hexdigest()}  {image}.img.xz\n')
+
+        # Sync only what we need:
+        run('Sync compressed image and checksum',
+            ['rsync', '-av', *Path('.').glob(f'{image}.img.xz*'), RSYNC_DEST])
+        logging.info('=== END: WORK WITH %s ===', image)
+
+    logging.info('=== BEGIN: CLEAN-UP ===')
+    run('Cleaning git',
+        ['git', 'clean', '-xdf'])
+    logging.info('=== END: CLEAN-UP ===')
+
+
+if __name__ == '__main__':
+    logging.basicConfig(level=logging.INFO,
+                        datefmt='%H:%M:%S',
+                        format='%(asctime)s %(message)s')
+    parser = argparse.ArgumentParser()
+    parser.add_argument('images', metavar='IMAGE', type=str, nargs='+',
+                        help='an image to build (e.g. raspi_4_bookworm)')
+    parser.add_argument('--sudo', action='store_true',
+                        help='generate the sudo snippet required to build specified images')
+    parser.add_argument('--build', action='store_true',
+                        help='build the specified images')
+    args = parser.parse_args()
+
+    login = os.getlogin()
+    uid = os.getuid()
+    gid = os.getgid()
+
+    if args.sudo:
+        sudo(args.images)
+        sys.exit(0)
+
+    if args.build:
+        build(args.images)
+        sys.exit(0)