Move container-hotplug from wrapper of docker to wrapper of runc

This means:
* It can now be used for other container managers, e.g. podman or k8s
* We now only start the container when existing devices are attached
* We no longer need to interface with docker API, and no longer have to
  worry about lifecycle of the pod.

The options is changed from using CLI to use annotations.

Cargo.toml

@@ -11,21 +11,18 @@ anyhow = { version = "1", features = ["backtrace"] }
 log = "0.4"
 env_logger = "0.11"
 clap = { version = "4", features = ["derive"] }
-bytes = "1"
 thiserror = "1"
 tokio = { version = "1", features = ["full"] }
 tokio-stream = "0.1"
-tokio-util = { version = "0.7", features = ["full"] }
 async-stream = "0.3"
 udev = "0.8"
-bollard = "0.16"
-rustix = { version = "0.38", features = ["fs", "stdio", "termios", "process", "thread"] }
+rustix = { version = "0.38", features = ["fs", "stdio", "process", "thread", "runtime", "pipe"] }
 bitflags = "2"
 once_cell = "1"
 humantime = "2"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
-
+inotify = "0.10"
 aya = { git = "https://github.com/aya-rs/aya.git" }
 
 [build-dependencies]

README.md

@@ -1,6 +1,6 @@
 # container-hotplug
 
-Hot-plug (and unplug) devices into a Docker container as they are (un)plugged.
+Hot-plug (and unplug) devices into a container as they are (un)plugged.
 
 ## Description
 
@@ -18,32 +18,82 @@ It then interfaces directly with the container's cgroup to grant it access to th
 To limit the devices the container can access, a _root device_ is specified.
 The container will receive access to any device descending from the root device.
 This is particularly useful if the root device is set to a USB hub.
-However, since hubs are rarely interesting, it can be specified as "the parent of device X",
+The hub can be specified directly, or it can be specified as "the parent of device X",
 e.g., we can giving a container access to all devices connected to the same hub as an Arduino board.
 
 Another concern is providing a container with well known paths for the devices.
 On bare-metal systems this would usually be achieved with a `SYMLINK` directive in a udev rule.
 This program tries to provide a similar functionality for containers, allowing you to specify symlinks for certain devices.
 
-This tool supports both cgroup v1 and v2.
+## Usage
 
-## Example
+This tool wraps `runc` command, with the additional hotplug feature. Therefore, it can be used as a drop in replace for
+many container managers/orchestrators that makes use of runc as runtime. You need to ensure `runc` is available in your `PATH`
+so `container-hotplug` can find it.
 
-Give a container access to all devices connected to the same hub as a CW310 board.
+It supports two annotations, `org.lowrisc.hotplug` and `org.lowrisc.symlinks`.
 
-1. Find the USB VID and PID of the device using `lsusb`, for a CW310 that is `2b3e:c310`
-2. Run (as root) the container using `container-hotplug`:
+For Docker, you can specify an alternative runtime by [changing /etc/docker/daemon.json](https://docs.docker.com/engine/alternative-runtimes/#youki):
+```json
+{
+  "runtimes": {
+    "youki": {
+      "path": "/path/to/container-hotplug/binary"
+    }
+  }
+}
 ```
-container-hotplug run \
-    -d parent-of:usb:2b3e:c310 \
-    -- -it ubuntu:22.04 bash
+and use it by `--runtime hotplug` and appropriate annotation, e.g.
+```bash
+sudo docker run --runtime hotplug -it --annotation org.lowrisc.hotplug=parent-of:usb:2b2e:c310 ubuntu:latest
 ```
 
-If you want symlinks to the `tty` devices created by interfaces 1 and 3 of the CW310, run:
+For podman, you can specify the path directly, by:
+```bash
+sudo podman run --runtime /path/to/container-hotplug/binary -it --annotation org.lowrisc.hotplug=parent-of:usb:2b2e:c310 ubuntu:latest
 ```
-container-hotplug run \
-    -d parent-of:usb:2b3e:c310 \
-    -l usb:2b3e:c310:1=/dev/ttyACM_CW310_0 \
-    -l usb:2b3e:c310:3=/dev/ttyACM_CW310_1 \
-    -- -it ubuntu:22.04 bash
-```
+
+For containerd (e.g. when using kubernetes), you can `/etc/containerd/config.toml` to add:
+```toml
+[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.hotplug]
+  runtime_type = "io.containerd.runc.v2"
+  pod_annotations = ["org.lowrisc.hotplug.*"]
+
+[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.hotplug.options]
+  SystemdCgroup = true
+  BinaryName = "/path/to/container-hotplug/binary"
+```
+this would allow you to use `hotplug` as handler in k8s, e.g. add a runtime class with
+```yaml
+apiVersion: node.k8s.io/v1
+kind: RuntimeClass
+metadata:
+  name: hotplug
+handler: hotplug
+```
+and use it in pod with
+```yaml
+apiVersion: v1
+kind: Pod
+metadata:
+  name: ubuntu
+  annotations:
+    org.lowrisc.hotplug.device: usb:0bda:5634
+spec:
+  runtimeClassName: hotplug
+  containers:
+  - name: ubuntu
+    image: ubuntu:latest
+    stdin: true
+    tty: true
+```
+
+If you want symlinks to the `tty` devices created by interfaces 1 and 3 of the CW310, add
+```
+--annotation org.lowrisc.hotplug.symlinks=usb:2b3e:c310:1=/dev/ttyACM_CW310_0,usb:2b3e:c310:3=/dev/ttyACM_CW310_1
+```
+to docker/podman command line or
+```
+org.lowrisc.hotplug.symlinks: usb:2b3e:c310:1=/dev/ttyACM_CW310_0,usb:2b3e:c310:3=/dev/ttyACM_CW310_1
+```
+to k8s config.

src/cli/mod.rs

@@ -1,48 +1,5 @@
 pub mod device;
 pub mod symlink;
 
-use clap::{Parser, Subcommand};
-
 pub use device::DeviceRef;
 pub use symlink::Symlink;
-
-#[derive(Parser)]
-pub struct Args {
-    #[command(subcommand)]
-    pub action: Action,
-}
-
-#[derive(Subcommand)]
-#[command(max_term_width = 180)]
-pub enum Action {
-    /// Wraps a call to `docker run` to allow hot-plugging devices into a
-    /// container as they are plugged
-    Run(Run),
-}
-
-#[derive(clap::Args)]
-pub struct Run {
-    #[arg(short = 'd', long, id = "DEVICE")]
-    /// Root hotplug device: [[parent-of:]*]<PREFIX>:<DEVICE> {n}
-    /// PREFIX can be: {n}
-    ///  - usb: A USB device identified as <VID>[:<PID>[:<SERIAL>]] {n}
-    ///  - syspath: A directory path in /sys/** {n}
-    ///  - devnode: A device path in /dev/** {n}
-    /// e.g., parent-of:usb:2b3e:c310
-    pub root_device: DeviceRef,
-
-    #[arg(short = 'l', long, id = "SYMLINK")]
-    /// Create a symlink for a device: <PREFIX>:<DEVICE>=<PATH> {n}
-    /// PREFIX can be: {n}
-    ///  - usb: A USB device identified as <VID>:<PID>:<INTERFACE> {n}
-    /// e.g., usb:2b3e:c310:1=/dev/ttyACM_CW310_0
-    pub symlink: Vec<Symlink>,
-
-    #[arg(short = 'u', long, default_value = "5", id = "CODE")]
-    /// Exit code to return when the root device is unplugged
-    pub root_unplugged_exit_code: u8,
-
-    #[arg(trailing_var_arg = true, id = "ARGS")]
-    /// Arguments to pass to `docker run`
-    pub docker_args: Vec<String>,
-}