Update shim README

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

README.md

@@ -10,7 +10,7 @@ This repository contains the following crates:
 | --- | --- |
 | [containerd-shim-protos](crates/shim-protos) | TTRPC bindings to shim interfaces |
 | [containerd-shim-logging](crates/logging) | Shim logger |
-| [containerd-shim](crates/shim) | Runtime v2 shim wrapper |
+| [containerd-shim](crates/shim) | 🚧 Runtime v2 shim wrapper |
 
 ## How to build
 The build process as easy as:

crates/shim/README.md

@@ -1 +1,54 @@
-# shim
+# containerd shim
+
+Rust crate to ease runtime v2 shim implementation.
+
+It replicates same [shim.Run](https://github.com/containerd/containerd/blob/dbef1d56d7ebc05bc4553d72c419ed5ce025b05d/runtime/v2/example/cmd/main.go)
+API offered by containerd's shim v2 runtime implementation written in Go.
+
+## Look and feel
+
+The API is very similar to the one offered by Go version:
+
+```rust
+struct Service;
+
+impl shim::Shim for Service {
+    fn new(_id: &str, _namespace: &str, _config: &mut shim::Config) -> Self {
+        Service {}
+    }
+
+    fn start_shim(&mut self, opts: StartOpts) -> Result<String, Box<dyn Error>> {
+        let address = shim::spawn(opts)?;
+        Ok(address)
+    }
+
+    fn delete_shim(&mut self) -> Result<api::DeleteResponse, Box<dyn Error>> {
+        todo!()
+    }
+}
+
+impl shim::Task for Service {
+    fn create(
+        &self,
+        ctx: &TtrpcContext,
+        req: api::CreateTaskRequest,
+    ) -> ::ttrpc::Result<api::CreateTaskResponse> {
+        debug!("Create");
+        Ok(api::CreateTaskResponse::default())
+    }
+}
+
+fn main() {
+    shim::run::<Service>("io.containerd.empty.v1")
+}
+```
+
+## How to use
+
+Runtime binary has to be [named in a special way](https://github.com/containerd/containerd/blob/main/runtime/v2/README.md#binary-naming) to be recognized by containerd:
+
+```bash
+$ cargo build --example empty-shim
+$ sudo cp ./target/debug/examples/empty-shim /usr/local/bin/containerd-shim-empty-v2
+$ sudo ctr run --rm --runtime io.containerd.empty.v2 -t docker.io/library/hello-world:latest hello
+```

crates/shim/examples/empty-shim.rs

@@ -1,37 +1,24 @@
-use std::error::Error;
-
 use containerd_shim as shim;
-use shim::protos;
+use shim::{api, TtrpcContext, TtrpcResult};
 
-use shim::api::DeleteResponse;
-use shim::StartOpts;
-
-use log::debug;
+use log::info;
 
 struct Service;
 
 impl shim::Shim for Service {
     fn new(_id: &str, _namespace: &str, _config: &mut shim::Config) -> Self {
-        todo!()
-    }
-
-    fn start_shim(&mut self, _opts: StartOpts) -> Result<String, Box<dyn Error>> {
-        todo!()
-    }
-
-    fn cleanup(&mut self) -> Result<DeleteResponse, Box<dyn Error>> {
-        todo!()
+        Service {}
     }
 }
 
 impl shim::Task for Service {
-    fn state(
+    fn create(
         &self,
-        _ctx: &shim::Context,
-        _request: shim::api::StateRequest,
-    ) -> protos::ttrpc::Result<shim::api::StateResponse> {
-        debug!("Get state");
-        Ok(shim::api::StateResponse::default())
+        _ctx: &TtrpcContext,
+        _req: api::CreateTaskRequest,
+    ) -> TtrpcResult<api::CreateTaskResponse> {
+        info!("Create");
+        Ok(api::CreateTaskResponse::default())
     }
 }
 

crates/shim/src/lib.rs

@@ -22,8 +22,10 @@ mod reap;
 
 pub use protos::shim::shim as api;
 pub use protos::shim::shim_ttrpc::Task;
+
 pub use protos::ttrpc;
-pub use protos::ttrpc::TtrpcContext as Context;
+pub use protos::ttrpc::Result as TtrpcResult;
+pub use protos::ttrpc::TtrpcContext;
 
 /// Config of shim binary options provided by shim implementations
 #[derive(Debug, Default)]
@@ -59,7 +61,7 @@ pub trait Shim: Task {
         Ok(address)
     }
 
-    fn cleanup(&mut self) -> Result<DeleteResponse, Box<dyn error::Error>> {
+    fn delete_shim(&mut self) -> Result<DeleteResponse, Box<dyn error::Error>> {
         Ok(DeleteResponse::default())
     }
 }
@@ -108,7 +110,7 @@ where
             Ok(())
         }
         "delete" => {
-            let response = shim.cleanup().map_err(Error::Cleanup)?;
+            let response = shim.delete_shim().map_err(Error::Cleanup)?;
 
             let stdout = io::stdout();
             let mut locked = stdout.lock();
@@ -122,12 +124,18 @@ where
             }
 
             let task_service = create_task(Arc::new(Box::new(shim)));
+
             let mut server = Server::new()
-                .bind(&flags.socket)?
-                .register_service(task_service);
+                .register_service(task_service)
+                .bind(format!("unix://{}", flags.socket).as_str())?;
 
             server.start()?;
 
+            // TODO: define exit criteria here.
+            std::thread::sleep(std::time::Duration::from_secs(360));
+
+            server.shutdown();
+
             Ok(())
         }
     }
@@ -170,10 +178,12 @@ pub fn socket_address(socket_path: &str, namespace: &str, id: &str) -> String {
         hasher.finish()
     };
 
-    format!("unix://{}/{:x}.sock", SOCKET_ROOT, hash)
+    format!("{}/{:x}.sock", SOCKET_ROOT, hash)
 }
 
-fn spawn(opts: StartOpts) -> Result<String, Error> {
+/// Spawn is a helper func to launch shim process.
+/// Typically this expected to be called from `StartShim`.
+pub fn spawn(opts: StartOpts) -> Result<String, Error> {
     let socket_address = socket_address(&opts.address, &opts.namespace, &opts.id);
 
     Command::new(env::current_exe()?)