First pass at image building script

build_image.py

@@ -0,0 +1,150 @@
+#!/usr/bin/python3
+
+import argparse
+import os
+import shutil
+import subprocess
+import tempfile
+
+
+parser = argparse.ArgumentParser(description='iconograph build_image')
+parser.add_argument(
+    '--arch',
+    dest='arch',
+    action='store',
+    default='amd64')
+parser.add_argument(
+    '--archive',
+    dest='archive',
+    action='store',
+    default='http://archive.ubuntu.com/ubuntu')
+parser.add_argument(
+    '--dest-iso',
+    dest='dest_iso',
+    action='store',
+    required=True)
+parser.add_argument(
+    '--release',
+    dest='release',
+    action='store',
+    required=True)
+parser.add_argument(
+    '--source-iso',
+    dest='source_iso',
+    action='store',
+    required=True)
+FLAGS = parser.parse_args()
+
+
+class ImageBuilder(object):
+
+  def __init__(self, source_iso, dest_iso, archive, arch, release):
+    self._source_iso = source_iso
+    self._dest_iso = dest_iso
+    self._archive = archive
+    self._arch = arch
+    self._release = release
+    self._umount = []
+    self._rmtree = []
+
+  def _Exec(self, *args):
+    print('+', args)
+    subprocess.check_call(args)
+
+  def _Debootstrap(self, root):
+    path = os.path.join(root, 'chroot')
+    os.mkdir(path)
+    self._Exec(
+        'debootstrap',
+        '--variant=buildd',
+        '--arch', self._arch,
+        self._release,
+        path,
+        self._archive)
+    return path
+
+  def _CreateUnion(self, root):
+    iso_path = os.path.join(root, 'iso')
+    os.mkdir(iso_path)
+    self._Exec(
+        'mount',
+        '--options', 'loop,ro',
+        self._source_iso,
+        iso_path)
+    self._umount.append(iso_path)
+
+    tmpfs_path = os.path.join(root, 'tmpfs')
+    os.mkdir(tmpfs_path)
+    self._Exec(
+        'mount',
+        '--types', 'tmpfs',
+        'none',
+        tmpfs_path)
+    self._umount.append(tmpfs_path)
+
+    upper_path = os.path.join(tmpfs_path, 'upper')
+    os.mkdir(upper_path)
+
+    work_path = os.path.join(tmpfs_path, 'work')
+    os.mkdir(work_path)
+
+    union_path = os.path.join(root, 'union')
+    os.mkdir(union_path)
+    self._Exec(
+        'mount', 
+        '--types', 'overlayfs',
+        '--options', 'lowerdir=%s,upperdir=%s,workdir=%s' % (iso_path, upper_path, work_path),
+        'none',
+        union_path)
+    self._umount.append(union_path)
+
+    return union_path
+
+  def _Squash(self, chroot_path, union_path):
+    self._Exec(
+        'mksquashfs',
+        chroot_path,
+        os.path.join(union_path, 'casper', 'filesystem.squashfs'),
+        '-noappend')
+
+  def _CreateISO(self, union_path):
+    self._Exec(
+        'grub-mkrescue',
+        '--verbose',
+        '--output=%s' % self._dest_iso,
+        union_path)
+
+  def _BuildImage(self):
+    root = tempfile.mkdtemp()
+    self._rmtree.append(root)
+
+    print('Building image in:', root)
+
+    chroot_path = self._Debootstrap(root)
+    union_path = self._CreateUnion(root)
+    self._Squash(chroot_path, union_path)
+    self._CreateISO(union_path)
+
+  def BuildImage(self):
+    try:
+      self._BuildImage()
+    finally:
+      pass
+      for path in self._umount:
+        self._Exec('umount', path)
+      for path in self._rmtree:
+        shutil.rmtree(path)
+
+
+def main():
+  builder = ImageBuilder(
+      FLAGS.source_iso,
+      FLAGS.dest_iso,
+      FLAGS.archive,
+      FLAGS.arch,
+      FLAGS.release)
+  builder.BuildImage()
+
+
+if __name__ == '__main__':
+  main()