[rfc] Add simplified libcontainer instance API

.github/workflows/action-build.yml

@@ -15,7 +15,7 @@ jobs:
     name: build on ${{ inputs.os }}
     runs-on: ${{ inputs.os }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup build env
         run: |
           os=$(echo "$RUNNER_OS" | tr '[:upper:]' '[:lower:]')

.github/workflows/action-fmt.yml

@@ -12,7 +12,7 @@ jobs:
     name: lint on ${{ inputs.os }}
     runs-on: ${{ inputs.os }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions-rust-lang/setup-rust-toolchain@v1
         with:
           components: rustfmt, clippy
@@ -25,11 +25,5 @@ jobs:
       - run: 
           # needed to run rustfmt in nightly toolchain
           rustup toolchain install nightly --component rustfmt
-      - name: Set environment variables for Windows
-        if: runner.os == 'Windows'
-        run: |
-          # required until standalong is implemented for windows (https://github.com/WasmEdge/wasmedge-rust-sdk/issues/54)
-          echo "WASMEDGE_LIB_DIR=C:\Program Files\WasmEdge\lib" >> $env:GITHUB_ENV
-          echo "WASMEDGE_INCLUDE_DIR=C:\Program Files\WasmEdge\include" >> $env:GITHUB_ENV
       - name: Run checks
         run: make check

.github/workflows/action-test-image.yml

@@ -8,7 +8,7 @@ jobs:
     name: build test image
     runs-on: "ubuntu-latest"
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: build
         run: make dist/img.tar
       - name: Upload artifacts

.github/workflows/action-test-k3s.yml

@@ -15,7 +15,7 @@ jobs:
     name: e2e k3s test on ${{ inputs.os }}
     runs-on: ${{ inputs.os }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup build env
         run: ./scripts/setup-linux.sh
         shell: bash

.github/workflows/action-test-kind.yml

@@ -15,7 +15,7 @@ jobs:
     name: e2e kind test on ${{ inputs.os }}
     runs-on: ${{ inputs.os }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup build env
         run: ./scripts/setup-linux.sh
         shell: bash

.github/workflows/action-test-smoke.yml

@@ -15,7 +15,7 @@ jobs:
     name: smoke test on ${{ inputs.os }}
     runs-on: ${{ inputs.os }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup build env
         run: ./scripts/setup-linux.sh
         shell: bash

.github/workflows/release.yml

@@ -20,7 +20,7 @@ jobs:
       crate: ${{ steps.parse-ref.outputs.crate }}
       version: ${{ steps.parse-ref.outputs.version }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           ref: ${{ github.ref }}
       - id: parse-ref
@@ -61,7 +61,7 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         with:
           key: release-${{ needs.generate.outputs.crate }}
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup build env
         run: ./scripts/setup-linux.sh
         shell: bash
@@ -82,7 +82,7 @@ jobs:
       - generate
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup buildx
         run: docker buildx create --use
       - name: build binaries

README.md

@@ -25,10 +25,19 @@ There are two modes of operation supported:
 1. "Normal" mode where there is 1 shim process per container or k8s pod.
 2. "Shared" mode where there is a single manager service running all shims in process.
 
-In either case you need to implement the `Instance` trait:
+In either case you need to implement a trait to teach runwasi how to use your wasm host.
+
+There are two ways to do this:
+* implementing the `sandbox::Instance` trait
+* or implementing the `container::Engine` trait
+
+The most flexible but complex is the `sandbox::Instance` trait:
 
 ```rust
 pub trait Instance {
+    /// The WASI engine type
+    type Engine: Send + Sync + Clone;
+
     /// Create a new instance
     fn new(id: String, cfg: Option<&InstanceConfig<Self::E>>) -> Self;
     /// Start the instance
@@ -48,6 +57,23 @@ pub trait Instance {
 }
 ```
 
+The `container::Engine` trait provides a simplified API:
+
+```rust
+pub trait Engine: Clone + Send + Sync + 'static {
+    /// The name to use for this engine
+    fn name() -> &'static str;
+    /// Run a WebAssembly container
+    fn run(&self, ctx: impl RuntimeContext, stdio: Stdio) -> Result<i32>;
+    /// Check that the runtime can run the container.
+    /// These checks run after the container creation and before the container start.
+    /// By default it checks that the entrypoint is an existing `.wasm` or `.wat` file.
+    fn can_handle(&self, ctx: impl RuntimeContext) -> Result<()> { /* default implementation*/ }
+}
+```
+
+After implementing `container::Engine` you can use `container::Instance<impl container::Engine>`, which implements the `sandbox::Instance` trait.
+
 To use your implementation in "normal" mode, you'll need to create a binary which has a main that looks something like this:
 
 ```rust
@@ -67,6 +93,25 @@ fn main() {
 }
 ```
 
+or when using the `container::Engine` trait, like this:
+
+```rust
+use containerd_shim as shim;
+use containerd_shim_wasm::{sandbox::ShimCli, container::{Instance, Engine}}
+
+struct MyEngine {
+    // ...
+}
+
+impl Engine for MyEngine {
+    // ...
+}
+
+fn main() {
+    shim::run::<ShimCli<Instance<Engine>>>("io.containerd.myshim.v1", opts);
+}
+```
+
 Note you can implement your own ShimCli if you like and customize your wasm engine and other things.
 I encourage you to checkout how that is implemented.