bib: use squashfs for the intermediate image

This commit moves to the new squashfs image support in the `images`
library (c.f. osbuild/images#1105)

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 +526,9 @@ 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.SquashfsCompression = "lz4"
+	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
 
@@ -605,7 +605,7 @@ def test_image_build_without_se_linux_denials(image_type):
 
 @pytest.mark.skipif(platform.system() != "Linux", reason="boot test only runs on linux right now")
 @pytest.mark.parametrize("image_type", gen_testcases("anaconda-iso"), indirect=["image_type"])
-def test_iso_installs(image_type):
+def test_iso_installs(tmp_path, image_type):
     installer_iso_path = image_type.img_path
     test_disk_path = installer_iso_path.with_name("test-disk.img")
     with open(test_disk_path, "w", encoding="utf8") as fp:
@@ -620,7 +620,15 @@ def test_iso_installs(image_type):
         exit_status, _ = vm.run("true", user=image_type.username, password=image_type.password)
         assert exit_status == 0
         assert_kernel_args(vm, image_type)
-
+    # validate that the install.img is squashfs
+    if not has_executable("unsquashfs"):
+        pytest.skip("need unsquashfs to check generate install.img")
+    with ExitStack as cm:
+        mount_point = tmp_path / "cdrom"
+        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 a valid squashfs
+        subprocess.check_call(["unsquashfs", "-ls", mount_point / "images/install.img"])
 
 def osinfo_for(it: ImageBuildResult, arch: str) -> str:
     base = "Media is an installer for OS"