volatile-binds: add recipe

This recipe is designed to play a key role in a read-only rootfs
of systemd based systems. It generates service files from a template,
volatile-binds.service.in and the VOLATILE_BINDS variable.

By default, VOLATILE_BINDS takes the value of "/var/volatile/lib /var/lib\n",
which leads to the generation of volatile-var-lib.service file.
This file doesn't have any effect in a read-write system, as it
has "ConditionPathIsReadWrite = !/var/lib" in the [Unit] section.
In other words, this file only has effect in a read-only rootfs.

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/meta/recipes-core/volatile-binds/files/volatile-binds.service.in b/meta/recipes-core/volatile-binds/files/volatile-binds.service.in
new file mode 100644
index 0000000000..32be5b4425
--- /dev/null
+++ b/meta/recipes-core/volatile-binds/files/volatile-binds.service.in
@@ -0,0 +1,19 @@
+[Unit]
+Description=Bind mount volatile @where@
+DefaultDependencies=false
+Before=local-fs.target
+RequiresMountsFor=@whatparent@ @whereparent@
+ConditionPathIsReadWrite=@whatparent@
+ConditionPathExists=@where@
+ConditionPathIsReadWrite=!@where@
+
+[Service]
+Type=oneshot
+RemainAfterExit=Yes
+StandardOutput=syslog
+TimeoutSec=0
+ExecStart=/sbin/mount-copybind @what@ @where@
+ExecStop=/sbin/umount @where@
+
+[Install]
+WantedBy=local-fs.target