Add build.rs to rebuild plugins, and a test plugin

crates/plugin_runtime/build.rs

@@ -0,0 +1,47 @@
+use std::path::Path;
+
+fn main() {
+    let base = Path::new("../../plugins");
+
+    // println!("cargo:rerun-if-changed=../../plugins/*");
+    println!("cargo:warning=Rebuilding plugins...");
+
+    let _ = std::fs::remove_dir_all(base.join("bin"));
+    let _ =
+        std::fs::create_dir_all(base.join("bin")).expect("Could not make plugins bin directory");
+
+    std::process::Command::new("cargo")
+        .args([
+            "build",
+            "--release",
+            "--target",
+            "wasm32-wasi",
+            "--manifest-path",
+            base.join("Cargo.toml").to_str().unwrap(),
+        ])
+        .status()
+        .expect("Could not build plugins");
+
+    let binaries = std::fs::read_dir(base.join("target/wasm32-wasi/release"))
+        .expect("Could not find compiled plugins in target");
+    println!("cargo:warning={:?}", binaries);
+
+    for file in binaries {
+        let is_wasm = || {
+            let path = file.ok()?.path();
+            if path.extension()? == "wasm" {
+                Some(path)
+            } else {
+                None
+            }
+        };
+
+        if let Some(path) = is_wasm() {
+            std::fs::copy(&path, base.join("bin").join(path.file_name().unwrap()))
+                .expect("Could not copy compiled plugin to bin");
+        }
+    }
+
+    // TODO: create .wat versions
+    // TODO: optimize with wasm-opt
+}