Add a deactivate subcommand.

src/activate.rs

@@ -15,3 +15,10 @@ pub fn activate(store_path: StorePath, ephemeral: bool) -> Result<()> {
     services::activate(store_path, ephemeral)?;
     Ok(())
 }
+
+pub fn deactivate() -> Result<()> {
+    log::info!("Deactivating system-manager");
+    etc_files::deactivate()?;
+    services::deactivate()?;
+    Ok(())
+}

src/activate/etc_files.rs

@@ -50,6 +50,14 @@ pub fn activate(store_path: StorePath, ephemeral: bool) -> Result<()> {
         .into_iter()
         .try_for_each(|(name, entry)| create_etc_link(&name, &entry, &etc_dir))?;
 
+    // TODO register the crated files (including .system-manager-static) in a
+    // state file, and clean up old files from the previous generation
+
+    Ok(())
+}
+
+// TODO we need to record in a state file which files we created and then remove them
+pub fn deactivate() -> Result<()> {
     Ok(())
 }
 

src/activate/services.rs

@@ -83,6 +83,29 @@ pub fn activate(store_path: StorePath, ephemeral: bool) -> Result<()> {
     Ok(())
 }
 
+pub fn deactivate() -> Result<()> {
+    let old_linked_services = read_linked_services()?;
+    log::debug!("{:?}", old_linked_services);
+
+    serialise_linked_services(&HashMap::new())?;
+
+    let service_manager = systemd::ServiceManager::new_session()?;
+    let timeout = Some(Duration::from_secs(30));
+
+    // We need to do this before we reload the systemd daemon, so that the daemon
+    // still knows about these units.
+    stop_services(&service_manager, &old_linked_services, &timeout)?;
+    unlink_services(&old_linked_services)?;
+
+    // We added all new services and removed old ones, so let's reload the units
+    // to tell systemd about them.
+    log::info!("Reloading the systemd daemon...");
+    service_manager.daemon_reload()?;
+
+    log::info!("Done");
+    Ok(())
+}
+
 fn unlink_services(services: &LinkedServices) -> Result<()> {
     services
         .values()

src/main.rs

@@ -41,6 +41,7 @@ enum Action {
         #[command(flatten)]
         build_args: BuildArgs,
     },
+    Deactivate,
     /// Generate a new system-manager generation
     Generate {
         #[command(flatten)]
@@ -75,6 +76,10 @@ fn go(action: Action) -> Result<()> {
         Action::Build {
             build_args: BuildArgs { flake_uri },
         } => build(flake_uri),
+        Action::Deactivate => {
+            check_root()?;
+            deactivate()
+        }
         Action::Generate {
             build_args: BuildArgs { flake_uri },
         } => {
@@ -110,6 +115,10 @@ fn activate(store_path: StorePath, ephemeral: bool) -> Result<()> {
     system_manager::activate::activate(store_path, ephemeral)
 }
 
+fn deactivate() -> Result<()> {
+    system_manager::activate::deactivate()
+}
+
 fn check_root() -> Result<()> {
     if !nix::unistd::Uid::is_root(nix::unistd::getuid()) {
         anyhow::bail!("We need root permissions.")