Add support for --init

Author: alexlarsson

composefs-run/src/main.rs

@@ -317,6 +317,10 @@ pub(crate) struct Cli {
     #[clap(short = 'i', long, hide = true)]
     interactive: bool,
 
+    /// Run an init process (catatonit) as PID 1 to forward signals
+    #[clap(long)]
+    init: bool,
+
     /// Add a host device to the container (HOST_PATH[:CONTAINER_PATH[:PERMISSIONS]])
     #[clap(long, value_parser = clap::value_parser!(DeviceSpec))]
     device: Vec<DeviceSpec>,

composefs-run/src/run.rs

@@ -371,6 +371,25 @@ fn setup_netns(bundle_dir: &Path) -> Result<PathBuf> {
     Ok(netns_path)
 }
 
+const CATATONIT_PATHS: &[&str] = &[
+    "/usr/libexec/catatonit/catatonit",
+    "/usr/libexec/podman/catatonit",
+    "/usr/local/libexec/podman/catatonit",
+    "/usr/local/lib/podman/catatonit",
+    "/usr/libexec/catatonit",
+    "/usr/bin/catatonit",
+];
+
+fn find_catatonit() -> Result<PathBuf> {
+    for path in CATATONIT_PATHS {
+        let p = Path::new(path);
+        if p.exists() {
+            return Ok(p.to_owned());
+        }
+    }
+    anyhow::bail!("catatonit not found")
+}
+
 fn setup_pasta(netns_path: &Path, pid_file: &Path, publish: &[PortSpec]) -> Result<i32> {
     let mut pasta_cmd = Command::new("pasta");
     pasta_cmd
@@ -556,7 +575,7 @@ fn build_runtime_spec(
 
     // ── Resolve image + CLI into effective values ───────────────────────
 
-    let args = if cli.cmd.is_empty() {
+    let mut args = if cli.cmd.is_empty() {
         let mut args = oci_config.entrypoint().clone().unwrap_or_default();
         args.extend(oci_config.cmd().clone().unwrap_or_default());
         ensure!(
@@ -568,6 +587,15 @@ fn build_runtime_spec(
         cli.cmd.clone()
     };
 
+    let init_path = if cli.init {
+        let path = find_catatonit().context("--init requires catatonit")?;
+        args.insert(0, "/dev/init".into());
+        args.insert(1, "--".into());
+        Some(path)
+    } else {
+        None
+    };
+
     let mut env: Vec<String> = oci_config.env().clone().unwrap_or_else(|| {
         vec!["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin".into()]
     });
@@ -932,6 +960,22 @@ fn build_runtime_spec(
     )?;
     mounts.extend(etc_mounts);
 
+    if let Some(ref path) = init_path {
+        mounts.push(
+            MountBuilder::default()
+                .typ("bind")
+                .source(path)
+                .destination("/dev/init")
+                .options(vec![
+                    "bind".into(),
+                    "ro".into(),
+                    "nosuid".into(),
+                    "nodev".into(),
+                ])
+                .build()?,
+        );
+    }
+
     spec.set_mounts(Some(mounts));
 
     // Poststop hook: unmount bundle and clean up the container directory