Add support for cgroups managed by systemd

Cargo.toml

@@ -22,3 +22,4 @@ once_cell = "1.6.0"
 futures = { version = "0.3", features = ["thread-pool"] }
 regex = "1.5"
 oci_spec = { version = "0.1.0", path = "./oci_spec" }
+systemd = "0.8.2"

src/cgroups/common.rs

@@ -10,6 +10,7 @@ use anyhow::{bail, Result};
 use nix::unistd::Pid;
 use oci_spec::LinuxResources;
 use procfs::process::Process;
+use systemd::daemon::booted;
 
 use crate::cgroups::v1;
 use crate::cgroups::v2;
@@ -50,7 +51,17 @@ pub fn write_cgroup_file<P: AsRef<Path>>(path: P, data: &str) -> Result<()> {
     Ok(())
 }
 
-pub fn create_cgroup_manager<P: Into<PathBuf>>(cgroup_path: P) -> Result<Box<dyn CgroupManager>> {
+pub fn create_cgroup_manager<P: Into<PathBuf>>(
+    cgroup_path: P,
+    systemd_cgroup: bool,
+) -> Result<Box<dyn CgroupManager>> {
+    if systemd_cgroup {
+        if !booted()? {
+            bail!("systemd cgroup flag passed, but systemd support for managing cgroups is not available");
+        }
+        log::info!("systemd cgroup manager will be used");
+        return Ok(Box::new(v1::SystemDCGroupManager::new(cgroup_path.into())?));
+    }
     let cgroup_mount = Process::myself()?
         .mountinfo()?
         .into_iter()
@@ -84,7 +95,7 @@ pub fn create_cgroup_manager<P: Into<PathBuf>>(cgroup_path: P) -> Result<Box<dyn
                     )?))
                 }
                 _ => Ok(Box::new(v1::manager::Manager::new(cgroup_path.into())?)),
-            } 
+            }
         }
         _ => bail!("could not find cgroup filesystem"),
     }

src/cgroups/v2/mod.rs

@@ -7,3 +7,5 @@ mod io;
 pub mod manager;
 mod memory;
 mod pids;
+pub mod systemd_manager;
+pub use systemd_manager::SystemDCGroupManager;

src/cgroups/v2/systemd_manager.rs

@@ -0,0 +1,24 @@
+use anyhow::Result;
+use nix::unistd::Pid;
+use oci_spec::LinuxResources;
+use std::path::PathBuf;
+
+use crate::cgroups::common::CgroupManager;
+
+pub struct SystemDCGroupManager {}
+
+impl SystemDCGroupManager {
+    pub fn new(cgroup_path: PathBuf) -> Result<Self> {
+        Ok(SystemDCGroupManager {})
+    }
+}
+
+impl CgroupManager for SystemDCGroupManager {
+    fn apply(&self, linux_resources: &LinuxResources, pid: Pid) -> Result<()> {
+        Ok(())
+    }
+
+    fn remove(&self) -> Result<()> {
+        Ok(())
+    }
+}

src/create.rs

@@ -31,7 +31,12 @@ pub struct Create {
 }
 
 impl Create {
-    pub fn exec(&self, root_path: PathBuf, command: impl Command) -> Result<()> {
+    pub fn exec(
+        &self,
+        root_path: PathBuf,
+        systemd_cgroup: bool,
+        command: impl Command,
+    ) -> Result<()> {
         let bundle_canonicalized = fs::canonicalize(&self.bundle)
             .unwrap_or_else(|_| panic!("failed to canonicalied {:?}", &self.bundle));
         let container_dir = root_path.join(&self.container_id);
@@ -80,6 +85,7 @@ impl Create {
             rootfs,
             spec,
             csocketfd,
+            systemd_cgroup,
             container,
             command,
         )?;
@@ -96,6 +102,7 @@ fn run_container<P: AsRef<Path>>(
     rootfs: PathBuf,
     spec: oci_spec::Spec,
     csocketfd: Option<FileDescriptor>,
+    systemd_cgroup: bool,
     container: Container,
     command: impl Command,
 ) -> Result<Process> {
@@ -104,7 +111,7 @@ fn run_container<P: AsRef<Path>>(
     let namespaces: Namespaces = linux.namespaces.clone().into();
 
     let cgroups_path = utils::get_cgroup_path(&linux.cgroups_path, container.id());
-    let cmanager = cgroups::common::create_cgroup_manager(&cgroups_path)?;
+    let cmanager = cgroups::common::create_cgroup_manager(&cgroups_path, systemd_cgroup)?;
 
     match fork::fork_first(
         pid_file,

src/main.rs

@@ -15,9 +15,8 @@ use youki::create;
 use youki::signal;
 use youki::start;
 
-use youki::utils;
 use youki::cgroups;
-
+use youki::utils;
 
 /// High-level commandline option definition
 /// This takes global options as well as individual commands as specified in [OCI runtime-spec](https://github.com/opencontainers/runtime-spec/blob/master/runtime.md)
@@ -32,6 +31,9 @@ struct Opts {
     log: Option<PathBuf>,
     #[clap(long)]
     log_format: Option<String>,
+    /// Enable systemd cgroup manager, rather then use the cgroupfs directly.
+    #[clap(short, long)]
+    systemd_cgroup: bool,
     /// command to actually manage container
     #[clap(subcommand)]
     subcmd: SubCommand,
@@ -81,8 +83,10 @@ fn main() -> Result<()> {
     let root_path = PathBuf::from(&opts.root);
     fs::create_dir_all(&root_path)?;
 
+    let systemd_cgroup = opts.systemd_cgroup;
+
     match opts.subcmd {
-        SubCommand::Create(create) => create.exec(root_path, LinuxCommand),
+        SubCommand::Create(create) => create.exec(root_path, systemd_cgroup, LinuxCommand),
         SubCommand::Start(start) => start.exec(root_path),
         SubCommand::Kill(kill) => {
             // resolves relative paths, symbolic links etc. and get complete path
@@ -144,7 +148,8 @@ fn main() -> Result<()> {
                     // remove the cgroup created for the container
                     // check https://man7.org/linux/man-pages/man7/cgroups.7.html
                     // creating and removing cgroups section for more information on cgroups
-                    let cmanager = cgroups::common::create_cgroup_manager(cgroups_path)?;
+                    let cmanager =
+                        cgroups::common::create_cgroup_manager(cgroups_path, systemd_cgroup)?;
                     cmanager.remove()?;
                 }
                 std::process::exit(0)