rust-extensions/crates/shim

Shim extension for containerd

Rust crate to ease runtime v2 shim implementation.

It replicates same shim.Run 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:

struct Service {
    exit: shim::ExitSignal,
}

impl shim::Shim for Service {
    fn new(
        _id: &str,
        _namespace: &str,
        _publisher: shim::RemotePublisher,
        _config: &mut shim::Config,
        exit: shim::ExitSignal,
    ) -> Self {
        Service { exit }
    }

    fn start_shim(&mut self, _opts: shim::StartOpts) -> Result<String, Box<dyn Error>> {
        let address = shim::spawn(opts)?;
        Ok(address)
    }
}

impl shim::Task for Service {
    fn create(
        &self,
        _ctx: &TtrpcContext,
        _req: api::CreateTaskRequest,
    ) -> TtrpcResult<api::CreateTaskResponse> {
        // New task nere...
        Ok(api::CreateTaskResponse::default())
    }

    fn connect(
        &self,
        _ctx: &TtrpcContext,
        _req: api::ConnectRequest,
    ) -> TtrpcResult<api::ConnectResponse> {
        info!("Connect request");
        Ok(api::ConnectResponse {
            version: String::from("example"),
            ..Default::default()
        })
    }

    fn shutdown(&self, _ctx: &TtrpcContext, _req: api::ShutdownRequest) -> TtrpcResult<api::Empty> {
        info!("Shutdown request");
        self.exit.signal(); // Signal to shutdown shim server
        Ok(api::Empty::default())
    }
}

fn main() {
    shim::run::<Service>("io.containerd.empty.v1")
}

How to use with containerd

With shim v2 runtime:

$ 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

Or if on 1.6+

$ cargo build --example empty-shim
ctr run --rm --runtime ./target/debug/examples/empty_shim docker.io/library/hello-world:latest hello

Or manually:

$ touch log

# Run containerd in background
$ sudo TTRPC_ADDRESS="/var/run/containerd/containerd.sock.ttrpc" \
    cargo run --example empty_shim -- \
    -namespace default \
    -id 1234 \
    -address /var/run/containerd/containerd.sock \
    -publish-binary ./bin/containerd \
    start
unix:///var/run/containerd/eb8e7d1c48c2a1ec.sock

$ cargo build --example connect
$ sudo ./target/debug/examples/connect unix:///var/run/containerd/eb8e7d1c48c2a1ec.sock
Connecting to unix:///var/run/containerd/eb8e7d1c48c2a1ec.sock...
Sending `Connect` request...
Connect response: version: "example"
Sending `Shutdown` request...
Shutdown response: ""

$ cat log
[INFO] server listen started
[INFO] server started
[INFO] Shim successfully started, waiting for exit signal...
[INFO] Connect request
[INFO] Shutdown request
[INFO] Shutting down shim instance
[INFO] close monitor
[INFO] listener shutdown for quit flag
[INFO] ttrpc server listener stopped
[INFO] listener thread stopped
[INFO] begin to shutdown connection
[INFO] connections closed
[INFO] reaper thread exited
[INFO] reaper thread stopped