Add function to write reboot-required file with context

This change adds a function that writes the /run/reboot-required file.
This function is called from any deployment operation with the relevant
context. Calling from rollback will ensure the rollback context along
with the image digest is written to the file, while calling from
upgrade or switch will write the deploy context for users to reference.

This expands on the functionality requested in: #1574
Related to: #1583

Signed-off-by: Brendan Shephard <bshephar@bne-home.net>

Author: bshephar

crates/lib/src/deploy.rs

@@ -792,9 +792,19 @@ pub(crate) async fn stage(
     })
     .await;
 
+    let bootc_action: String = String::from("deploy");
+
     // Unconditionally create or update /run/reboot-required to signal a reboot is needed.
     // This is monitored by kured (Kubernetes Reboot Daemon).
-    let reboot_message = format!("bootc: Reboot required for image: {}", &spec.image.image);
+    write_reboot_required(&image.manifest_digest.as_ref(), bootc_action.as_str())?;
+
+    Ok(())
+}
+
+/// Update the /run/reboot-required file with the action we're performing,
+/// and the image that will be active after the reboot.
+fn write_reboot_required(image: &str, action: &str) -> Result<()> {
+    let reboot_message = format!("bootc {}: Reboot required for image: {}", action, image);
     let run_dir = Dir::open_ambient_dir("/run", cap_std::ambient_authority())?;
     run_dir
         .atomic_write("reboot-required", reboot_message.as_bytes())
@@ -870,6 +880,12 @@ pub(crate) async fn rollback(sysroot: &Storage) -> Result<()> {
         println!("Next boot: rollback deployment");
     }
 
+    let bootc_action: String = String::from("rollback");
+    write_reboot_required(
+        rollback_image.manifest_digest.as_ref(),
+        bootc_action.as_str(),
+    )?;
+
     sysroot.update_mtime()?;
 
     Ok(())