bib: use plain squashfs for the ISO rootfs

This commit moves to the new "flat" squashfs rootfs image
that is now available in the `images` library (c.f.
osbuild/images#1105).

This will ensures we are no longer using the previous "ext4"
intermediate image that gave problems for big rootfses.

Closes: #733

.github/workflows/tests.yml

@@ -79,7 +79,7 @@ jobs:
     - name: Install test dependencies
       run: |
         sudo apt update
-        sudo apt install -y python3-pytest python3-paramiko python3-boto3 flake8 qemu-system-x86 qemu-efi-aarch64 qemu-system-arm qemu-user-static pylint libosinfo-bin
+        sudo apt install -y python3-pytest python3-paramiko python3-boto3 flake8 qemu-system-x86 qemu-efi-aarch64 qemu-system-arm qemu-user-static pylint libosinfo-bin squashfs-tools
     - name: Diskspace (before)
       run: |
         df -h

bib/cmd/bootc-image-builder/image.go

@@ -526,7 +526,8 @@ func manifestForISO(c *ManifestConfig, rng *rand.Rand) (*manifest.Manifest, erro
 	default:
 		return nil, fmt.Errorf("unsupported architecture %v", c.Architecture)
 	}
-
+	// see https://github.com/osbuild/bootc-image-builder/issues/733
+	img.RootfsType = manifest.SquashfsRootfs
 	img.Filename = "install.iso"
 
 	mf := manifest.New()

test/test_build.py

@@ -9,7 +9,7 @@
 import subprocess
 import tempfile
 import uuid
-from contextlib import contextmanager
+from contextlib import contextmanager, ExitStack
 from typing import NamedTuple
 from dataclasses import dataclass
 
@@ -654,6 +654,22 @@ def test_iso_os_detection(image_type):
     assert osinfo_output == expected_output
 
 
+@pytest.mark.skipif(platform.system() != "Linux", reason="osinfo detect test only runs on linux right now")
+@pytest.mark.skipif(not testutil.has_executable("unsquashfs"), reason="need unsquashfs")
+@pytest.mark.parametrize("image_type", gen_testcases("anaconda-iso"), indirect=["image_type"])
+def test_iso_install_img_is_squashfs(tmp_path, image_type):
+    installer_iso_path = image_type.img_path
+    with ExitStack() as cm:
+        mount_point = tmp_path / "cdrom"
+        mount_point.mkdir()
+        subprocess.check_call(["mount", installer_iso_path, os.fspath(mount_point)])
+        cm.callback(subprocess.check_call, ["umount", os.fspath(mount_point)])
+        # ensure install.img is the "flat" squashfs, before PR#777 the content
+        # was an intermediate ext4 image "squashfs-root/LiveOS/rootfs.img"
+        output = subprocess.check_output(["unsquashfs", "-ls", mount_point / "images/install.img"], text=True)
+        assert "usr/bin/bootc" in output
+
+
 @pytest.mark.parametrize("images", gen_testcases("multidisk"), indirect=["images"])
 def test_multi_build_request(images):
     artifacts = set()