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.

docs/src/SUMMARY.md

@@ -28,6 +28,8 @@
 - [`man bootc-rollback`](man/bootc-rollback.md)
 - [`man bootc-usr-overlay`](man/bootc-usr-overlay.md)
 - [`man bootc-fetch-apply-updates.service`](man-md/bootc-fetch-apply-updates.service.md)
+- [`man bootc-status-updated.path`](man-md/bootc-status-updated.path.md)
+- [`man bootc-status-updated.target`](man-md/bootc-status-updated.target.md)
 - [Controlling bootc via API](bootc-via-api.md)
 
 # Using `bootc install`

docs/src/man-md/bootc-status-updated.path.md

@@ -0,0 +1,19 @@
+% bootc-status-updated.path(8)
+
+# NAME
+
+bootc-status-updated.path
+
+# DESCRIPTION
+
+This unit watches the `bootc` root directory (/ostree/bootc) for
+modification, and triggers the companion `bootc-status-updated.target`
+systemd unit.
+
+The `bootc` program updates the mtime on its root directory when the
+contents of `bootc status` changes as a result of an
+update/upgrade/edit/switch/rollback operation.
+
+# SEE ALSO
+
+**bootc**(1), **bootc-status-updated.target**(8)

docs/src/man-md/bootc-status-updated.target.md

@@ -0,0 +1,23 @@
+% bootc-status-updated.target(8)
+
+# NAME
+
+bootc-status-updated.target
+
+# DESCRIPTION
+
+This unit is triggered by the companion `bootc-status-updated.path`
+systemd unit.  This target is intended to enable users to add custom
+services to trigger as a result of `bootc status` changing.
+
+Add the following to your unit configuration to active it when `bootc
+status` changes:
+
+```
+[Install]
+WantedBy=bootc-status-updated.target
+```
+
+# SEE ALSO
+
+**bootc**(1), **bootc-status-updated.path**(8)

systemd/bootc-status-updated.path

@@ -0,0 +1,10 @@
+[Unit]
+Description=Monitor bootc for status changes
+Documentation=man:bootc-status-updated.path(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-status-updated.target(8)
+StopWhenUnneeded=true