Support removal of systemd unit

crates/libcgroups/src/systemd/dbus/client.rs

@@ -27,7 +27,7 @@ impl Client {
     /// start_transient_unit is a higher level API for starting a unit
     /// for a specific container under systemd.
     /// See https://www.freedesktop.org/wiki/Software/systemd/dbus for more details.
-    pub fn start_transient_unit_for_container(
+    pub fn start_transient_unit(
         &self,
         container_name: &str,
         pid: u32,
@@ -37,11 +37,7 @@ impl Client {
         // To view and introspect the methods under the 'org.freedesktop.systemd1' destination
         // and object path under it use the following command:
         // `gdbus introspect --system --dest org.freedesktop.systemd1 --object-path /org/freedesktop/systemd1`
-        let proxy = self.conn.with_proxy(
-            "org.freedesktop.systemd1",
-            "/org/freedesktop/systemd1",
-            Duration::from_millis(5000),
-        );
+        let proxy = self.create_proxy();
 
         // To align with runc, yuoki will always add the following properties to its container units:
         // - CPUAccounting=true
@@ -61,8 +57,6 @@ impl Client {
         if unit_name.ends_with("slice") {
             properties.push(("Wants", Variant(Box::new(parent.to_owned()))));
         } else {
-            log::debug!("SELECTED SCOPE");
-            log::debug!("{}", parent);
             properties.push(("Slice", Variant(Box::new(parent.to_owned()))));
             properties.push(("Delegate", Variant(Box::new(true))));
         }
@@ -77,7 +71,21 @@ impl Client {
 
         proxy
             .start_transient_unit(unit_name, "replace", properties, vec![])
-            .context("failed to start transient unit")?;
+            .with_context(|| {
+                format!(
+                    "failed to start transient unit {}, parent is {}",
+                    unit_name, parent
+                )
+            })?;
+        Ok(())
+    }
+
+    pub fn stop_transient_unit(&self, unit_name: &str) -> Result<()> {
+        let proxy = self.create_proxy();
+
+        proxy
+            .stop_unit(unit_name, "replace")
+            .with_context(|| format!("failed to stop unit {}", unit_name))?;
         Ok(())
     }
 

crates/libcgroups/src/systemd/manager.rs

@@ -1,4 +1,5 @@
 use std::{
+    fmt::Display,
     fs::{self},
     os::unix::fs::PermissionsExt,
     path::Component::RootDir,
@@ -41,10 +42,16 @@ pub struct Manager {
 #[derive(Debug)]
 struct CgroupsPath {
     parent: String,
-    scope: String,
+    prefix: String,
     name: String,
 }
 
+impl Display for CgroupsPath {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}:{}:{}", self.parent, self.prefix, self.name)
+    }
+}
+
 impl Manager {
     pub fn new(root_path: PathBuf, cgroups_path: PathBuf, container_name: String) -> Result<Self> {
         // TODO: create the systemd unit using a dbus client.
@@ -91,7 +98,7 @@ impl Manager {
 
         Ok(CgroupsPath {
             parent: parent.to_owned(),
-            scope: prefix.to_owned(),
+            prefix: prefix.to_owned(),
             name: name.to_owned(),
         })
     }
@@ -101,7 +108,7 @@ impl Manager {
     fn get_unit_name(cgroups_path: &CgroupsPath) -> String {
         // By default we create a scope unless specified explicitly.
         if !cgroups_path.name.ends_with(".slice") {
-            return format!("{}-{}.scope", cgroups_path.scope, cgroups_path.name);
+            return format!("{}-{}.scope", cgroups_path.prefix, cgroups_path.name);
         }
         cgroups_path.name.clone()
     }
@@ -234,7 +241,7 @@ impl CgroupManager for Manager {
         }
 
         self.client
-            .start_transient_unit_for_container(
+            .start_transient_unit(
                 &self.container_name,
                 pid.as_raw() as u32,
                 &self.destructured_path.parent,
@@ -265,7 +272,10 @@ impl CgroupManager for Manager {
     }
 
     fn remove(&self) -> Result<()> {
-        Ok(())
+        log::debug!("remove {}", self.unit_name);
+        self.client
+            .stop_transient_unit(&self.unit_name)
+            .with_context(|| format!("could not remove control group {}", self.destructured_path))
     }
 
     fn freeze(&self, state: FreezerState) -> Result<()> {