systemd: New bootc-fetch-apply-updates.{timer,service}

Let's ship a baseline systemd unit that can be enabled
for automatic updates.

Signed-off-by: Colin Walters <walters@verbum.org>

Makefile

@@ -9,8 +9,16 @@ all-test:
 install:
 	install -D -m 0755 -t $(DESTDIR)$(prefix)/bin target/release/bootc
 	install -d $(DESTDIR)$(prefix)/lib/bootc/install
+	# Support installing pre-generated man pages shipped in source tarball, to avoid
+	# a dependency on pandoc downstream
+	if test -d man; then install -D -m 0644 -t $(DESTDIR)$(prefix)/share/man/man5 man/*.5; fi
 	if test -d man; then install -D -m 0644 -t $(DESTDIR)$(prefix)/share/man/man8 man/*.8; fi
 
+# These are not installed by default; one recommendation is to put them in a separate
+# sub-package or sub-component.
+install-systemd-auto:
+	install -D -m 0644 -t $(DESTDIR)/$(prefix)/lib/systemd/system systemd/*.service systemd/*.timer
+
 bin-archive: all
 	$(MAKE) install DESTDIR=tmp-install && tar --zstd -C tmp-install -cf target/bootc.tar.zst . && rm tmp-install -rf
 

manpages-md-extra/bootc-fetch-apply-updates.service.md

@@ -0,0 +1,27 @@
+# NAME
+
+bootc-fetch-apply-updates.service
+
+# DESCRIPTION
+
+This service causes `bootc` to perform the following steps:
+
+- Check the source registry for an updated container image
+- If one is found, download it
+- Reboot
+
+This service also comes with a companion `bootc-fetch-apply-updates.timer`
+systemd unit.  The current default systemd timer shipped in the upstream
+project is enabled for daily updates.
+
+However, it is fully expected that different operating systems
+and distributions choose different defaults.
+
+## Customizing updates
+
+Note that all three of these steps can be decoupled; they
+are:
+
+- `bootc upgrade --check`
+- `bootc upgrade`
+- `bootc upgrade --apply`

systemd/bootc-fetch-apply-updates.service

@@ -0,0 +1,8 @@
+[Unit]
+Description=Apply bootc updates
+Documentation=man:bootc(8)
+ConditionPathExists=/run/ostree-booted
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/bootc update --apply --quiet

systemd/bootc-fetch-apply-updates.timer

@@ -0,0 +1,12 @@
+[Unit]
+Description=Apply bootc updates
+Documentation=man:bootc(8)
+ConditionPathExists=/run/ostree-booted
+
+[Timer]
+OnBootSec=1h
+# This time is relatively arbitrary and obviously expected to be overridden/changed
+OnUnitInactiveSec=8h
+
+[Install]
+WantedBy=timers.target

xtask/src/xtask.rs

@@ -79,12 +79,37 @@ fn gitrev(sh: &Shell) -> Result<String> {
 
 #[context("Manpages")]
 fn manpages(sh: &Shell) -> Result<()> {
+    // We currently go: clap (Rust) -> man -> markdown for the CLI
     sh.create_dir("target/man")?;
     cmd!(
         sh,
         "cargo run --features=docgen -- man --directory target/man"
     )
     .run()?;
+    // We also have some man pages for the systemd units which are canonically
+    // maintained as markdown; convert them to man pages.
+    let extradir = sh.current_dir().join("manpages-md-extra");
+    for ent in std::fs::read_dir(extradir)? {
+        let ent = ent?;
+        let srcpath = ent.path();
+        let extension = if let Some(extension) = srcpath.extension() {
+            extension
+        } else {
+            continue;
+        };
+        if extension != "md" {
+            continue;
+        }
+        let base_filename = srcpath
+            .file_stem()
+            .and_then(|name| name.to_str())
+            .ok_or_else(|| anyhow!("Expected filename in {srcpath:?}"))?;
+        cmd!(
+            sh,
+            "pandoc --from=markdown --to=man --output=target/man/{base_filename}.5 {srcpath}"
+        )
+        .run()?;
+    }
     Ok(())
 }