runtime-rs: Add -info flag support for containerd v2.0+

Add -info flag handling to containerd-shim-kata-v2 (Rust version).
This outputs RuntimeInfo protobuf (name, version, revision) to stdout,
providing compatibility with containerd v2.0+ which queries runtime
information via this flag.

This is the runtime-rs counterpart to the Go implementation.

Fixes #12133

Signed-off-by: tak-ka3 <takumi.hiraoka@acompany-ac.com>

Cargo.lock

@@ -4005,6 +4005,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "common",
+ "containerd-shim-protos",
  "go-flag",
  "logging",
  "nix 0.26.4",

src/runtime-rs/Cargo.toml

@@ -22,6 +22,7 @@ cloud-hypervisor = ["runtimes/cloud-hypervisor"]
 
 [dependencies]
 anyhow = { workspace = true }
+containerd-shim-protos = { workspace = true }
 go-flag = { workspace = true }
 nix = { workspace = true }
 tokio = { workspace = true, features = ["rt", "rt-multi-thread"] }

src/runtime-rs/crates/shim/src/bin/main.rs

@@ -6,10 +6,15 @@
 
 use std::{
     ffi::{OsStr, OsString},
+    io::Write,
     path::PathBuf,
 };
 
 use anyhow::{anyhow, Context, Result};
+use containerd_shim_protos::{
+    protobuf::Message,
+    types::introspection::{RuntimeInfo, RuntimeVersion},
+};
 use nix::{
     mount::{mount, MsFlags},
     sched::{self, CloneFlags},
@@ -29,11 +34,13 @@ enum Action {
     Delete(Args),
     Help,
     Version,
+    Info,
 }
 
 fn parse_args(args: &[OsString]) -> Result<Action> {
     let mut help = false;
     let mut version = false;
+    let mut info = false;
     let mut shim_args = Args::default();
 
     // Crate `go_flag` is used to keep compatible with go/flag package.
@@ -46,6 +53,7 @@ fn parse_args(args: &[OsString]) -> Result<Action> {
         flags.add_flag("publish-binary", &mut shim_args.publish_binary);
         flags.add_flag("help", &mut help);
         flags.add_flag("version", &mut version);
+        flags.add_flag("info", &mut info);
     })
     .context(Error::ParseArgument(format!("{args:?}")))?;
 
@@ -53,6 +61,8 @@ fn parse_args(args: &[OsString]) -> Result<Action> {
         Ok(Action::Help)
     } else if version {
         Ok(Action::Version)
+    } else if info {
+        Ok(Action::Info)
     } else if rest_args.is_empty() {
         Ok(Action::Run(shim_args))
     } else if rest_args[0] == "start" {
@@ -83,6 +93,8 @@ fn show_help(cmd: &OsStr) {
         enable debug output in logs
   -id string
         id of the task
+  -info
+        output the runtime info as protobuf (for containerd v2.0+)
   -namespace string
         namespace that owns the shim
   -publish-binary string
@@ -114,6 +126,25 @@ fn show_version(err: Option<anyhow::Error>) {
     }
 }
 
+fn show_info() -> Result<()> {
+    let mut version = RuntimeVersion::new();
+    version.version = config::RUNTIME_VERSION.to_string();
+    version.revision = config::RUNTIME_GIT_COMMIT.to_string();
+
+    let mut info = RuntimeInfo::new();
+    info.name = config::CONTAINERD_RUNTIME_NAME.to_string();
+    info.version = Some(version).into();
+
+    let data = info
+        .write_to_bytes()
+        .context("failed to marshal RuntimeInfo")?;
+    std::io::stdout()
+        .write_all(&data)
+        .context("failed to write RuntimeInfo to stdout")?;
+
+    Ok(())
+}
+
 fn get_tokio_runtime() -> Result<tokio::runtime::Runtime> {
     let worker_threads = std::env::var(ENV_TOKIO_RUNTIME_WORKER_THREADS)
         .unwrap_or_default()
@@ -155,6 +186,7 @@ fn real_main() -> Result<()> {
         }
         Action::Help => show_help(&args[0]),
         Action::Version => show_version(None),
+        Action::Info => show_info().context("show info")?,
     }
     Ok(())
 }