to-disk: Fix cross-device link errors with AlmaLinux and similar images

Closes: #125

Switch to bind-mounting /var/tmp from the outer VM into the inner
podman container. I think we fixed this in newer bootc, but
this ensures compatibility with older versions.

Also add AlmaLinux to the test matrix and creates a parameterized
integration test that validates to-disk works across all supported
bootc images. Deduplicates disk validation logic into a shared helper
function.

Assisted-by: Claude Code (Sonnet 4.5)
Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

Justfile

@@ -1,5 +1,5 @@
 PRIMARY_IMAGE := "quay.io/centos-bootc/centos-bootc:stream10"
-ALL_BASE_IMAGES := "quay.io/fedora/fedora-bootc:42 quay.io/centos-bootc/centos-bootc:stream9 quay.io/centos-bootc/centos-bootc:stream10"
+ALL_BASE_IMAGES := "quay.io/fedora/fedora-bootc:42 quay.io/centos-bootc/centos-bootc:stream9 quay.io/centos-bootc/centos-bootc:stream10 quay.io/almalinuxorg/almalinux-bootc:9.6"
 
 # Build the native binary
 build:

crates/integration-tests/src/tests/to_disk.rs

@@ -16,38 +16,27 @@
 
 use camino::Utf8PathBuf;
 use color_eyre::Result;
-use integration_tests::integration_test;
+use integration_tests::{integration_test, parameterized_integration_test};
 use linkme::distributed_slice;
 
 use std::process::Command;
 use tempfile::TempDir;
 
-use crate::{get_test_image, run_bcvk, INTEGRATION_TEST_LABEL};
-
-/// Test actual bootc installation to a disk image
-fn test_to_disk() -> Result<()> {
-    let temp_dir = TempDir::new().expect("Failed to create temp directory");
-    let disk_path = Utf8PathBuf::try_from(temp_dir.path().join("test-disk.img"))
-        .expect("temp path is not UTF-8");
-
-    let output = run_bcvk(&[
-        "to-disk",
-        "--label",
-        INTEGRATION_TEST_LABEL,
-        &get_test_image(),
-        disk_path.as_str(),
-    ])?;
-
-    assert!(
-        output.success(),
-        "to-disk failed with exit code: {:?}. stdout: {}, stderr: {}",
-        output.exit_code(),
-        output.stdout,
-        output.stderr
-    );
-
-    let metadata = std::fs::metadata(&disk_path).expect("Failed to get disk metadata");
-    assert!(metadata.len() > 0);
+use crate::{get_test_image, run_bcvk, CapturedOutput, INTEGRATION_TEST_LABEL};
+
+/// Validate that a disk image was created successfully with proper bootc installation
+///
+/// This helper function verifies:
+/// - The disk image file exists and has non-zero size
+/// - The disk has valid partition table (using sfdisk)
+/// - The installation completed successfully (from output messages)
+fn validate_disk_image(
+    disk_path: &Utf8PathBuf,
+    output: &CapturedOutput,
+    context: &str,
+) -> Result<()> {
+    let metadata = std::fs::metadata(disk_path).expect("Failed to get disk metadata");
+    assert!(metadata.len() > 0, "{}: Disk image is empty", context);
 
     // Verify the disk has partitions using sfdisk -l
     let sfdisk_output = Command::new("sfdisk")
@@ -60,14 +49,16 @@ fn test_to_disk() -> Result<()> {
 
     assert!(
         sfdisk_output.status.success(),
-        "sfdisk failed with exit code: {:?}",
+        "{}: sfdisk failed with exit code: {:?}",
+        context,
         sfdisk_output.status.code()
     );
 
     assert!(
         sfdisk_stdout.contains("Disk ")
             && (sfdisk_stdout.contains("sectors") || sfdisk_stdout.contains("bytes")),
-        "sfdisk output doesn't show expected disk information"
+        "{}: sfdisk output doesn't show expected disk information",
+        context
     );
 
     let has_partitions = sfdisk_stdout.lines().any(|line| {
@@ -76,15 +67,43 @@ fn test_to_disk() -> Result<()> {
 
     assert!(
         has_partitions,
-        "No bootc partitions found in sfdisk output. Output was:\n{}",
-        sfdisk_stdout
+        "{}: No bootc partitions found in sfdisk output. Output was:\n{}",
+        context, sfdisk_stdout
     );
 
     assert!(
         output.stdout.contains("Installation complete") || output.stderr.contains("Installation complete"),
-        "No 'Installation complete' message found in output. This indicates bootc install did not complete successfully. stdout: {}, stderr: {}",
+        "{}: No 'Installation complete' message found in output. This indicates bootc install did not complete successfully. stdout: {}, stderr: {}",
+        context,
         output.stdout, output.stderr
     );
+
+    Ok(())
+}
+
+/// Test actual bootc installation to a disk image
+fn test_to_disk() -> Result<()> {
+    let temp_dir = TempDir::new().expect("Failed to create temp directory");
+    let disk_path = Utf8PathBuf::try_from(temp_dir.path().join("test-disk.img"))
+        .expect("temp path is not UTF-8");
+
+    let output = run_bcvk(&[
+        "to-disk",
+        "--label",
+        INTEGRATION_TEST_LABEL,
+        &get_test_image(),
+        disk_path.as_str(),
+    ])?;
+
+    assert!(
+        output.success(),
+        "to-disk failed with exit code: {:?}. stdout: {}, stderr: {}",
+        output.exit_code(),
+        output.stdout,
+        output.stderr
+    );
+
+    validate_disk_image(&disk_path, &output, "test_to_disk")?;
     Ok(())
 }
 integration_test!(test_to_disk);
@@ -112,9 +131,6 @@ fn test_to_disk_qcow2() -> Result<()> {
         output.stderr
     );
 
-    let metadata = std::fs::metadata(&disk_path).expect("Failed to get disk metadata");
-    assert!(metadata.len() > 0);
-
     // Verify the file is actually qcow2 format using qemu-img info
     let qemu_img_output = Command::new("qemu-img")
         .args(["info", disk_path.as_str()])
@@ -135,11 +151,7 @@ fn test_to_disk_qcow2() -> Result<()> {
         qemu_img_stdout
     );
 
-    assert!(
-        output.stdout.contains("Installation complete") || output.stderr.contains("Installation complete"),
-        "No 'Installation complete' message found in output. This indicates bootc install did not complete successfully. stdout: {}, stderr: {}",
-        output.stdout, output.stderr
-    );
+    validate_disk_image(&disk_path, &output, "test_to_disk_qcow2")?;
     Ok(())
 }
 integration_test!(test_to_disk_qcow2);
@@ -215,3 +227,38 @@ fn test_to_disk_caching() -> Result<()> {
     Ok(())
 }
 integration_test!(test_to_disk_caching);
+
+/// Test to-disk with various bootc images to ensure compatibility
+///
+/// This parameterized test runs to-disk with multiple container images,
+/// particularly testing AlmaLinux which had cross-device link issues (issue #125)
+fn test_to_disk_multi_image(image: &str) -> Result<()> {
+    let temp_dir = TempDir::new().expect("Failed to create temp directory");
+    let disk_path = Utf8PathBuf::try_from(temp_dir.path().join("test-disk.img"))
+        .expect("temp path is not UTF-8");
+
+    let output = run_bcvk(&[
+        "to-disk",
+        "--label",
+        INTEGRATION_TEST_LABEL,
+        image,
+        disk_path.as_str(),
+    ])?;
+
+    assert!(
+        output.success(),
+        "to-disk with image {} failed with exit code: {:?}. stdout: {}, stderr: {}",
+        image,
+        output.exit_code(),
+        output.stdout,
+        output.stderr
+    );
+
+    validate_disk_image(
+        &disk_path,
+        &output,
+        &format!("test_to_disk_multi_image({})", image),
+    )?;
+    Ok(())
+}
+parameterized_integration_test!(test_to_disk_multi_image);

crates/kit/src/to_disk.rs

@@ -245,9 +245,10 @@ impl ToDiskOpts {
 
             # Execute bootc installation, having the outer podman pull from
             # the virtiofs store on the host, as well as the inner bootc.
+            # Mount /var/tmp into inner container to avoid cross-device link errors (issue #125)
             export STORAGE_OPTS=additionalimagestore=${AIS}
             podman run --rm -i ${tty} --privileged --pid=host --net=none -v /sys:/sys:ro \
-                 -v /var/lib/containers:/var/lib/containers -v /dev:/dev -v ${AIS}:${AIS} --security-opt label=type:unconfined_t \
+                 -v /var/lib/containers:/var/lib/containers -v /var/tmp:/var/tmp -v /dev:/dev -v ${AIS}:${AIS} --security-opt label=type:unconfined_t \
                 --env=STORAGE_OPTS \
                 {INSTALL_LOG} \
                 {SOURCE_IMGREF} \