packaging: Add systemd unit to trigger updates on boot

Add a systemd service unit to trigger an adoption and update on every
boot.

Note that the service is intentionally not enabled by default as it
should be up to the distribution to add a systemd preset if auto-update
for the bootloader is desired.

This unit does not come with any specific restrictions (i.e. EFI or BIOS
only). For an assesment of the safety of updates as performed by
bootupd, see coreos#454.

Distributiuons should also apply the restrictions (i.e. EFI or BIOS only
for example) as needed as unit files overrides.

Notably, Fedora CoreOS can not yet enable automatic updates until we get
support for the multiple EFI partitions for RAID setups.

See: coreos/fedora-coreos-tracker#1468
See: coreos/fedora-coreos-config#3042

Initial version from: coreos#716
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2332868

Makefile

@@ -41,6 +41,9 @@ install-grub-static:
 	install -m 644 -D -t ${DESTDIR}$(PREFIX)/lib/bootupd/grub2-static src/grub2/*.cfg
 	install -m 755 -d ${DESTDIR}$(PREFIX)/lib/bootupd/grub2-static/configs.d
 
+install-systemd-unit:
+	install -m 644 -D -t "${DESTDIR}$(PREFIX)/lib/systemd/system/" contrib/packaging/bootloader-update.service
+
 bin-archive:
 	rm target/inst -rf
 	$(MAKE) install install-grub-static DESTDIR=$$(pwd)/target/inst

contrib/packaging/bootloader-update.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=Update bootloader on boot
+Documentation=https://github.com/coreos/bootupd
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/bootupctl update
+RemainAfterExit=yes
+MountFlags=slave
+
+[Install]
+WantedBy=multi-user.target

contrib/packaging/bootupd.spec

@@ -24,6 +24,7 @@ BuildRequires: cargo
 BuildRequires: git
 BuildRequires: openssl-devel
 BuildRequires: systemd-devel
+BuildRequires: systemd-rpm-macros
 
 %description 
 %{summary}
@@ -34,6 +35,7 @@ BuildRequires: systemd-devel
 %{_bindir}/bootupctl
 %{_libexecdir}/bootupd
 %{_prefix}/lib/bootupd/grub2-static/
+%{_unitdir}/bootloader-update.service
 
 %prep
 %autosetup -n %{crate}-%{version} -p1 -Sgit
@@ -53,7 +55,8 @@ cargo build --release
 %install
 %make_install INSTALL="install -p -c"
 make install-grub-static DESTDIR=%{?buildroot} INSTALL="%{__install} -p"
+make install-systemd-unit DESTDIR=%{?buildroot} INSTALL="%{__install} -p"
 
 %changelog
 * Tue Oct 18 2022 Colin Walters <[email protected]> - 0.2.8-3
-- Dummy changelog
+- Dummy changelog