[PATCH v3 3/3] oe-selftest: overlayfs: Add a demo case for /etc

uvv.mail
2026-01-14T18:55:47Z

/etc is a special directory. It's possible to create a mount unit for
it, but many system services that start early at boot time will not
rescan its content when you mount overlay on top. The added test case
demonstrates this by adding a sample systemd service and enabling it in
overlay.

Signed-off-by: Vyacheslav Yurkov <uvv.mail@gmail.com>
---
meta/lib/oeqa/selftest/cases/overlayfs.py | 98 +++++++++++++++++++++++
1 file changed, 98 insertions(+)

diff --git a/meta/lib/oeqa/selftest/cases/overlayfs.py b/meta/lib/oeqa/selftest/cases/overlayfs.py
index 3e55e97927..426b4ccee3 100644
--- a/meta/lib/oeqa/selftest/cases/overlayfs.py
+++ b/meta/lib/oeqa/selftest/cases/overlayfs.py
@@ -263,6 +263,104 @@ EOT

self._test_correct_image('systemd-machine-units', systemd_machine_unit_append)

+ @skipIfNotMachine("qemux86-64", "tests are qemux86-64 specific currently")
+ def test_etc_mount(self):
+ """
+ Summary: /etc is not supposed to be used with overlayfs.bbclass
+ Expected: Observe inconsistencies after using etc overlay with a mount unit
+ Author: Vyacheslav Yurkov <uvv.mail@gmail.com>
+ """
+ systemd_machine_unit_append = """
+SYSTEMD_SERVICE:${PN} += " \
+ data.mount \
+ etc.mount \
+"
+
+do_install:append() {
+ install -d ${D}${systemd_system_unitdir}
+ install -d ${D}${ROOT_HOME}
+ cat <<EOT > ${D}${systemd_system_unitdir}/etc.mount
+[Unit]
+Description=OverlayFS mount for /etc directory
+DefaultDependencies=no
+RequiresMountsFor=/data
+
+[Mount]
+What=overlay
+Where=/etc
+Type=overlay
+Options=lowerdir=/etc,upperdir=/data/overlay/etc,workdir=/data/overlay-workdir/etc
+[Install]
+WantedBy=local-fs.target
+EOT
+
+ cat <<EOT >${D}${systemd_system_unitdir}/data.mount
+[Unit]
+Description=Persistent storage partition
+
+[Mount]
+What=/dev/sda3
+Where=/data
+Type=ext4
+Options=defaults
+
+[Install]
+WantedBy=local-fs.target
+EOT
+ cat <<EOT > ${D}${ROOT_HOME}/test-daemon.service
+[Unit]
+Description=My one-shot task
+After=local-fs.target
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/echo test
+RemainAfterExit=yes
+
+[Install]
+WantedBy=multi-user.target
+EOT
+}
+
+FILES:${PN} += "${ROOT_HOME}"
+"""
+
+ config = """
+IMAGE_INSTALL:append = " systemd-machine-units"
+DISTRO_FEATURES:append = " overlayfs"
+
+# Use systemd as init manager
+INIT_MANAGER = "systemd"
+
+# enable overlayfs in the kernel
+KERNEL_EXTRA_FEATURES:append = " features/overlayfs/overlayfs.scc"
+
+IMAGE_FSTYPES += "wic"
+WKS_FILE = "overlayfs_etc.wks.in"
+OVERLAYFS_ROOTFS_TYPE = "ext4"
+"""
+
+ self.write_config(config)
+
+ machine_inc = """
+OVERLAYFS_MOUNT_POINT[etc] = "/etc"
+OVERLAYFS_QA_SKIP[mnt-overlay] = "mount-configured"
+"""
+ self.set_machine_config(machine_inc)
+ self.write_recipeinc('systemd-machine-units', systemd_machine_unit_append)
+ bitbake('core-image-minimal')
+ with runqemu('core-image-minimal', image_fstype='wic', discard_writes=False) as qemu:
+ test_daemon_path = get_bb_var('ROOT_HOME') + '/test-daemon.service'
+ status, output = qemu.run_serial('cp -f ' + test_daemon_path + ' /etc/systemd/system/')
+ status, output = qemu.run_serial("systemctl enable test-daemon")
+ status, output = qemu.run_serial("sync")
+ with runqemu('core-image-minimal', image_fstype='wic') as qemu:
+ # Check the test service status. It's enabled and supposed to start, but it didn't
+ status, output = qemu.run_serial("systemctl is-enabled test-daemon")
+ self.assertTrue("enabled" in output, msg=output)
+ status, output = qemu.run_serial("systemctl is-active test-daemon")
+ self.assertTrue("inactive" in output, msg=output)
+
@OETestTag("runqemu")
class OverlayFSEtcRunTimeTests(OESelftestTestCase):
"""overlayfs-etc class tests"""