systemd: Ensure /run and /var/run are the same on R/O rootfs

According to upstream, this one has non-backward-compatible API changes, so porting of end users' code will be required. On the other hand, the library also got a stable API now.

Signed-off-by Jan Kundr?t <[email protected]>

There's a bug in 0.2 which prevents proper operation when activated via D-Bus, which is why I'm bumping this.

Signed-off-by Jan Kundr?t <[email protected]>

Link https://github.com/rauc/rauc/issues/125

---
 package/rauc/rauc.hash | 4 ++--
 package/rauc/rauc.mk   | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

When I updated systemd from 234 to 237 and D-Bus from 1.12.0 to 1.12.2 on my system with a read-only rootfs (buildroot 1c0c55c028 to buildroot 27d2229692), my D-Bus-activated services stopped working. Checking the logs, it turned out that systemd PID 1 was not able to connect the D-Bus socket at all. There were some recent changes in systemd where upstream refactored code which waits for sockets to appear. However, the real problem is that systemd is configured to look for the D-Bus socket in /run/dbus, while D-Bus creates it at /var/run/dbus/. D-Bus upstream explains in a bugreport [1] that this "traditional" /var/run/dbus is going to stay because it's hardcoded in other independent implementations of the D-Bus APIs.

As is also said in that bugreport, the root cause is that /run and /var/run are effectively two separate directories on Buildroot -- at least when configured for a R/O rootfs. Furthermore, systemd actually actively warns about this:

systemd[1]: System is tainted: var-run-bad

Looking further, systemd-tmpfiles also detects breakage:

systemd-tmpfiles[172]: [/usr/lib/tmpfiles.d/var.conf:12] Duplicate line for path "/var/run", ignoring. systemd-tmpfiles[172]: [/usr/lib/tmpfiles.d/var.conf:14] Duplicate line for path "/var/log", ignoring. systemd-tmpfiles[172]: [/usr/lib/tmpfiles.d/var.conf:21] Duplicate line for path "/var/lib", ignoring.

This change simply skips /var/run from being copied from the /usr/share/factory. The symlink is still created by another tmpfiles.d entry which belongs to systemd.

The other warnings are still in present:

systemd-tmpfiles[174]: [/usr/lib/tmpfiles.d/var.conf:14] Duplicate line for path "/var/log", ignoring. systemd-tmpfiles[174]: [/usr/lib/tmpfiles.d/var.conf:21] Duplicate line for path "/var/lib", ignoring.

I'm leaving that one to someone who is more familiar with systemd and buildroot conventions. My box now boots again, so I'm happy :).

[1] https://bugs.freedesktop.org/show_bug.cgi?id=101628

Signed-off-by Jan Kundr?t <[email protected]>

---
 package/skeleton-init-systemd/skeleton-init-systemd.mk | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

package/skeleton-init-systemd/skeleton-init-systemd.mk +3 -1

index a2d4e8c4b3..95142904f5 100644
@@ -42,7 +42,9 @@ define SKELETON_INIT_SYSTEMD_PRE_ROOTFS_VAR
 	mkdir $(TARGET_DIR)/var
 	for i in $(TARGET_DIR)/usr/share/factory/var/*; do \
 		j="$${i#$(TARGET_DIR)/usr/share/factory}"; \
-		if [ -L "$${i}" ]; then \
+		if [ "$${j}" = "/var/run" ]; then \
+			echo "# $${j} is being handled by systemd"
+		elif [ -L "$${i}" ]; then \
 			printf "L+! %s - - - - %s\n" \
 				"$${j}" "../usr/share/factory/$${j}" \
 			|| exit 1; \

Signature · 7 lines

2.14.3


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