tests: Add integration coverage for switch --from-delta

Exercise offline delta switching on booted Fedora systems with the
ostree and composefs backends. Build a derived target in the guest and
create its delta against an archive of the original install image.
Remove the target from container storage, apply the delta, and verify
the image digest and marker file after reboot.

Disable /boot automount idle expiry on ostree so shutdown finalization
can activate the staged deployment. Skip sealed UKI cases because the
guest-local builder produces unsigned images.

Generated-by: AI
Signed-off-by: Alexander Larsson <alexl@redhat.com>

Author: alexlarsson

hack/provision-fetch.sh

@@ -43,7 +43,7 @@ case "${ID}-${VERSION_ID}" in
         rm -rf "${td}"
         ;;
     "fedora-"*)
-        dnf -y install nu
+        dnf -y install nu oci-delta
         ;;
 esac
 

tmt/plans/integration.fmf

@@ -344,6 +344,23 @@ execute:
     because: only the image_mode test image installs bootc-tests
   extra-skip_if_ostree: true
 
+/plan-51-switch-from-delta:
+  summary: Switch to a derived image using an OCI delta and verify after reboot
+  discover:
+    how: fmf
+    test:
+      - /tmt/tests/tests/test-51-switch-from-delta
+  adjust:
+  - when: distro != fedora
+    enabled: false
+    because: oci-delta is packaged in Fedora
+  - when: boot_type == uki and seal_state == sealed
+    enabled: false
+    because: the guest-local UKI builder produces unsigned images
+  extra-export_image: true
+  environment:
+    BOOTC_source_image_archive: /sysroot/bootc-source.oci.tar
+
 /plan-52-install-repart:
   summary: Test bootc install to-disk with systemd-repart partitioning
   discover:

tmt/tests/booted/test-switch-from-delta.nu

@@ -0,0 +1,93 @@
+# number: 51
+# extra:
+#   export_image: true
+# tmt:
+#   summary: Switch to a derived image using an OCI delta and verify after reboot
+#   duration: 30m
+#   adjust:
+#     - when: distro != fedora
+#       enabled: false
+#       because: oci-delta is packaged in Fedora
+#     - when: boot_type == uki and seal_state == sealed
+#       enabled: false
+#       because: the guest-local UKI builder produces unsigned images
+#
+use std assert
+use tap.nu
+
+const image = "localhost/bootc-delta-target:latest"
+const delta = "/var/tmp/image-1-to-2.oci-delta"
+const state = "/var/tmp/bootc-delta-state.json"
+const marker = "/usr/share/testing-bootc-delta"
+
+def initial_build [] {
+    tap begin "switch from OCI delta"
+    assert (not ($marker | path exists))
+    let st = bootc status --json | from json
+
+    if not (tap is_composefs) {
+        let automounted = (
+            do { ^findmnt --mountpoint /boot --types autofs --noheadings } | complete
+        ).exit_code == 0
+        if $automounted {
+            # An expired /boot breaks ostree finalization: https://github.com/bootc-dev/bootc/issues/2402
+            let dropin = "/etc/systemd/system/boot.automount.d/bootc-delta-test.conf"
+            mkdir ($dropin | path dirname)
+            "[Automount]\nTimeoutIdleSec=0\n" | save $dropin
+            systemctl daemon-reload
+            systemctl restart boot.automount
+        }
+    }
+
+    let source_archive = $env.BOOTC_source_image_archive? | default "/sysroot/bootc-source.oci.tar"
+    assert ($source_archive | path exists) $"Missing source image archive: ($source_archive)"
+    skopeo copy $"oci-archive:($source_archive)" containers-storage:localhost/bootc
+
+    (tap make_uki_containerfile $"
+        FROM localhost/bootc as base
+        RUN echo delta-upgrade > ($marker)
+    ") | save Dockerfile
+    podman build --network=none -t $image .
+
+    let target = skopeo inspect $"containers-storage:($image)" | from json
+    let reference = $"localhost/bootc-delta-target@($target.Digest)"
+    assert ($target.Digest != $st.status.booted.image.imageDigest)
+
+    oci-delta create $"oci-archive:($source_archive)" $"containers-storage:($image)" $delta
+    # Keep the target available only through the delta.
+    podman rmi $image
+
+    {
+        image: $reference
+        digest: $target.Digest
+        composefs: (tap is_composefs)
+    } | to json | save $state
+
+    bootc switch --from-delta $delta $reference
+    let staged = (bootc status --json | from json).status.staged.image
+    assert equal $staged.image.transport registry
+    assert equal $staged.image.image $reference
+    assert equal $staged.imageDigest $target.Digest
+    assert (not ($marker | path exists))
+    tmt-reboot
+}
+
+def verify_delta [] {
+    let expected = open $state
+    let booted = (bootc status --json | from json).status.booted.image
+    assert equal $booted.image.transport registry
+    assert equal $booted.image.image $expected.image
+    assert equal $booted.imageDigest $expected.digest
+    assert equal (open $marker | str trim) delta-upgrade
+    assert equal (tap is_composefs) $expected.composefs
+    bootc internals fsck
+    tap ok
+}
+
+def main [] {
+    match $env.TMT_REBOOT_COUNT? {
+        null | "0" => initial_build,
+        "1" => verify_delta,
+        $o => { error make { msg: $"Invalid TMT_REBOOT_COUNT ($o)" } },
+    }
+}

tmt/tests/tests.fmf

@@ -216,6 +216,18 @@ check:
     because: only the image_mode test image installs bootc-tests
   test: bootc-integration-tests booted switch-zstd-chunked
 
+/test-51-switch-from-delta:
+  summary: Switch to a derived image using an OCI delta and verify after reboot
+  duration: 30m
+  adjust:
+  - when: distro != fedora
+    enabled: false
+    because: oci-delta is packaged in Fedora
+  - when: boot_type == uki and seal_state == sealed
+    enabled: false
+    because: the guest-local UKI builder produces unsigned images
+  test: nu booted/test-switch-from-delta.nu
+
 /test-52-install-repart:
   summary: Test bootc install to-disk with systemd-repart partitioning
   duration: 30m