osbuild: use bootc install to deploy the container

Instead of deploying the container to the tree then copy all the contents
to the disk image, use bootc to directly manage the installation to the
target filesystems.

Right now this requires to use the image as the buildroot so this
requires python (for osbuild). This is tracked in [1].

[1] bootc-dev/bootc#1410
Requires osbuild/osbuild#2149

Author: jbtrystram

build.sh

@@ -177,6 +177,7 @@ write_archive_info() {
 }
 
 patch_osbuild() {
+   # return # we have no patches right now
    ## Add a few patches that either haven't made it into a release or
    ## that will be obsoleted with other work that will be done soon.
 
@@ -191,6 +192,7 @@ patch_osbuild() {
    #cat foo.patch | patch -d /usr/lib/osbuild -p1
    patch -d /usr/lib/osbuild -p1 < /usr/lib/coreos-assembler/0001-live-artifacts-read-os-name-from-usr-lib-os-release.patch
 
+   patch -d /usr/lib/osbuild -p1 < src/0001-stages-ignition-parametrize-the-path-to-boot.patch
    ## And then move the files back; supermin appliance creation will need it back
    ## in the places delivered by the RPM.
    mv /usr/lib/osbuild/tools/osbuild-mpp /usr/bin/osbuild-mpp

src/0001-stages-ignition-parametrize-the-path-to-boot.patch

@@ -0,0 +1,69 @@
+From e37bd5d256c02f2a7693ec220322cf131e8e5274 Mon Sep 17 00:00:00 2001
+From: jbtrystram <[email protected]>
+Date: Thu, 17 Jul 2025 15:59:27 +0200
+Subject: [PATCH] stages/ignition: parametrize the path to boot
+
+Allow passing a mount to specify where to write the igntion.firstboot
+file.
+This keeps the default `tree:///` value to not break existing stages.
+---
+ stages/org.osbuild.ignition           | 13 ++++++++-----
+ stages/org.osbuild.ignition.meta.json |  5 +++++
+ 2 files changed, 13 insertions(+), 5 deletions(-)
+
+diff --git a/stages/org.osbuild.ignition b/stages/org.osbuild.ignition
+index 23f91c48..4466cabf 100755
+--- a/stages/org.osbuild.ignition
++++ b/stages/org.osbuild.ignition
+@@ -2,18 +2,17 @@
+ import sys
+ 
+ import osbuild.api
++from osbuild.util import parsing
+ 
+ 
+-def main(tree, options):
+-    network = options.get("network", [])
+-
++def main(network, location):
+     # grub, when detecting the '/boot/ignition.firstboot' file
+     # will set the "ignition_firstboot" option so that ignition
+     # gets triggered during that boot. Additionally, the file
+     # itself will be sourced this the 'ignition_network_kcmdline'
+     # that is also in the "ignition_firstboot" variable can be
+     # overwritten with the contents of `network`
+-    with open(f"{tree}/boot/ignition.firstboot", "w", encoding="utf8") as f:
++    with open(f"{location}/ignition.firstboot", "w", encoding="utf8") as f:
+         if network:
+             netstr = " ".join(network)
+             f.write(f"set ignition_network_kcmdline='{netstr}'")
+@@ -23,5 +22,9 @@ def main(tree, options):
+ 
+ if __name__ == '__main__':
+     args = osbuild.api.arguments()
+-    r = main(args["tree"], args.get("options", {}))
++    options = args.get("options", {})
++    target = options.get("target", "tree:///boot")
++    location = parsing.parse_location(target, args)
++    network = options.get("network", [])
++    r = main(network, location)
+     sys.exit(r)
+diff --git a/stages/org.osbuild.ignition.meta.json b/stages/org.osbuild.ignition.meta.json
+index 612d59c7..dd295c24 100644
+--- a/stages/org.osbuild.ignition.meta.json
++++ b/stages/org.osbuild.ignition.meta.json
+@@ -22,6 +22,11 @@
+         "items": {
+           "type": "string"
+         }
++      },
++      "target": {
++        "type": "string",
++        "description": "Location to write the 'ignition.firstboot' file.",
++        "default": "tree:///boot"
+       }
+     }
+   }
+-- 
+2.50.1
+