systemd: Add bootc-status-updated.{path,target} units

This adds a new systemd path unit which activates on bootc status
changing, and in turn triggers a new systemd target.  This allows
adding arbitrary new systemd services with `WantedBy =
bootc-status-updated.target` that will be activated each time the
bootc status is updated.

Signed-off-by: John Eckersberg <[email protected]>

Author: jeckersb

Makefile

@@ -24,7 +24,7 @@ install:
 	    install -D -m 0644 -t $(DESTDIR)$(prefix)/share/man/man8 $$d/*.8; \
 	  fi; \
 	  done
-	install -D -m 0644 -t $(DESTDIR)/$(prefix)/lib/systemd/system systemd/*.service systemd/*.timer
+	install -D -m 0644 -t $(DESTDIR)/$(prefix)/lib/systemd/system systemd/*.service systemd/*.timer systemd/*.path systemd/*.target
 
 # Run this to also take over the functionality of `ostree container` for example.
 # Only needed for OS/distros that have callers invoking `ostree container` and not bootc.

systemd/bootc-status-updated.path

@@ -0,0 +1,10 @@
+[Unit]
+Description=Monitor bootc for status changes
+Documentation=man:bootc(8)
+
+[Path]
+PathChanged=/ostree/bootc
+Unit=bootc-status-updated.target
+
+[Install]
+WantedBy=multi-user.target

systemd/bootc-status-updated.target

@@ -0,0 +1,4 @@
+[Unit]
+Description=Target for bootc status changes
+Documentation=man:bootc(8)
+StopWhenUnneeded=true