bootc-base-imagectl: support injecting directories

Right now, the expectation for adding unpackaged content in a custom
base image flow is to do it after the main compose. The problem however
is that sometimes you want that content to affect the main compose
itself, so doing it afterwards is not sufficient.

The primary use case for this is sysusers.d dropins where you need
to make sure that sysusers in scriptlets don't pick UIDs/GIDs already
reserved on target client systems.

One way to work around this is to synthesize an RPM that ships the
dropin, and then ensure that it somehow runs as early as possible in the
transaction. This is doable but obviously quite a hack.

Enable this instead by adding a generic `--add-dir` switch which then
just translates to `ostree-layers` in the override manifest.

The dnf equivalent would be to first install e.g. `filesystem` and
`setup`, add files to the rootfs, and then install all the other
packages.

See also discussions in https://github.com/coreos/rpm-ostree/pull/5354.

bootc-base-imagectl

@@ -22,20 +22,35 @@ def run_build_rootfs(args):
     else:
         manifest_path = f'/{MANIFESTDIR}/{args.manifest}.yaml'
 
-    tmp_manifest = None
+    rpmostree_argv = ['rpm-ostree', 'compose', 'rootfs']
+
+    override_manifest = {}
+    tmp_ostree_repo = None
     if args.install:
         additional_pkgs = set(args.install)
         if len(additional_pkgs) > 0:
-            final_manifest = {
-                "include": manifest_path,
-                "packages": list(additional_pkgs),
-            }
-            tmp_manifest = tempfile.NamedTemporaryFile(mode='w', encoding='utf-8', suffix='.json', delete_on_close=False)
-            json.dump(final_manifest, tmp_manifest)
-            tmp_manifest.close()
-            manifest_path = tmp_manifest.name
+            override_manifest['packages'] = list(additional_pkgs)
+    if args.add_dir:
+        tmp_ostree_repo = tempfile.mkdtemp(dir='/var/tmp')
+        subprocess.check_call(['ostree', 'init', '--repo', tmp_ostree_repo, '--mode=bare'])
+        rpmostree_argv.append(f"--ostree-repo={tmp_ostree_repo}")
+        override_manifest['ostree-layers'] = []
+
+        for dir in args.add_dir:
+            base = os.path.basename(dir)
+            # capture output to hide commit digest printed
+            subprocess.check_output(['ostree', 'commit', '--repo', tmp_ostree_repo, '-b', f'overlay/{base}', dir,
+                                     '--owner-uid=0', '--owner-gid=0', '--no-xattrs', '--mode-ro-executables'])
+            override_manifest['ostree-layers'].append(f'overlay/{base}')
+
+    tmp_manifest = None
+    if override_manifest:
+        override_manifest['include'] = manifest_path
+        tmp_manifest = tempfile.NamedTemporaryFile(mode='w', encoding='utf-8', suffix='.json', delete_on_close=False)
+        json.dump(override_manifest, tmp_manifest)
+        tmp_manifest.close()
+        manifest_path = tmp_manifest.name
 
-    rpmostree_argv = ['rpm-ostree', 'compose', 'rootfs']
     try:
         if args.cachedir != "":
             rpmostree_argv.append(f"--cachedir={args.cachedir}")
@@ -66,6 +81,8 @@ def run_build_rootfs(args):
     finally:
         if tmp_manifest is not None:
             del tmp_manifest
+        if tmp_ostree_repo:
+            shutil.rmtree(tmp_ostree_repo)
 
     # Copy our own build configuration into the target if configured;
     # this is used for the first stage build. But by default *secondary*
@@ -123,6 +140,7 @@ if __name__ == "__main__":
     build_rootfs.add_argument("--manifest", help="Use the specified manifest", action='store', default='default')
     build_rootfs.add_argument("--install", help="Add a package", action='append', default=[], metavar='PACKAGE')
     build_rootfs.add_argument("--cachedir", help="Cache repo metadata and RPMs in specified directory", action='store', default='')
+    build_rootfs.add_argument("--add-dir", help='Copy dir contents into the target', action='append', default=[], metavar='DIR')
     build_rootfs.add_argument("source_root", help="Path to the source root directory used for dnf configuration (default=/)", nargs='?', default='/')
     build_rootfs.add_argument("target", help="Path to the target root directory that will be generated.")
     build_rootfs.set_defaults(func=run_build_rootfs)