napi: build the musl addons against a dynamic C runtime and smoke them on Alpine

.github/workflows/napi.yml

@@ -25,35 +25,41 @@ jobs:
       - uses: dtolnay/rust-toolchain@6bed0761d98439e5a578e2877258200ad565ba87 # stable
         with:
           targets: ${{ matrix.target }}
-      - if: matrix.musl
-        run: sudo apt-get update && sudo apt-get install -y musl-tools
       - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
         with:
           node-version: 22
       - name: Build the addon
+        if: ${{ !matrix.musl }}
         working-directory: napi
         run: cargo build --locked --release --target ${{ matrix.target }}
+      - name: Build the addon on Alpine
+        # A musl cdylib linked on the Ubuntu runner does not load in a musl Node, so the musl
+        # builds link with Alpine's own toolchain. musl links the C runtime statically by
+        # default, and a static runtime cannot go into a cdylib, hence -crt-static.
+        if: matrix.musl
+        run: |
+          docker run --rm -v "$PWD:/src" -w /src/napi \
+            -e RUSTFLAGS='-C target-feature=-crt-static' rust:1-alpine \
+            sh -c 'apk add --no-cache musl-dev >/dev/null && cargo build --locked --release --target ${{ matrix.target }}'
       - name: Package it
         working-directory: napi
         shell: bash
         run: node scripts/platform-package.mjs ${{ matrix.platform }} target/${{ matrix.target }}/release/${{ matrix.lib }} dist/${{ matrix.platform }}
       - name: Load it and install a real package
         # A cross-built addon cannot load on this runner; the native ones prove the whole path.
-        if: ${{ !contains(matrix.platform, 'musl') && matrix.platform != 'darwin-x64' && matrix.platform != 'win32-arm64' }}
+        if: ${{ !matrix.musl && matrix.platform != 'darwin-x64' && matrix.platform != 'win32-arm64' }}
         working-directory: napi
         shell: bash
         run: |
           cp dist/${{ matrix.platform }}/microbe.${{ matrix.platform }}.node .
-          node -e '
-            const { install, installSync } = require("./index.js");
-            const dir = require("node:path").join(process.env.RUNNER_TEMP, "napi-smoke");
-            const done = installSync(["is-odd@^3"], dir);
-            if (done.roots[0].name !== "is-odd") throw new Error(JSON.stringify(done));
-            install({ typescript: "5" }, dir).then((r) => {
-              if (!r.bins.tsc) throw new Error(JSON.stringify(r));
-              console.log(r.roots.map((x) => x.name + "@" + x.version).join(" "), Object.keys(r.bins));
-            });
-          '
+          node scripts/smoke.cjs
+      - name: Load it and install a real package, on Alpine
+        # The runner's Node is glibc; a musl build loads only in a musl Node.
+        if: matrix.musl
+        working-directory: napi
+        run: |
+          cp dist/${{ matrix.platform }}/microbe.${{ matrix.platform }}.node .
+          docker run --rm -v "$PWD:/napi" node:22-alpine node /napi/scripts/smoke.cjs
       - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
         with:
           name: microbe-${{ matrix.platform }}

napi/index.js

@@ -24,11 +24,12 @@ try {
 } catch (fromPackage) {
   try {
     native = require(`./microbe.${platform}.node`);
-  } catch {
-    const err = new Error(
-      `@nubjs/microbe has no build for ${platform}. Install failed for @nubjs/microbe-${platform}: ${fromPackage.message}`,
-    );
-    err.cause = fromPackage;
+  } catch (fromFile) {
+    // A build that exists but cannot load is the failure worth reporting; a missing
+    // local file only means this is not a checkout.
+    const cause = fromFile.code === "MODULE_NOT_FOUND" ? fromPackage : fromFile;
+    const err = new Error(`@nubjs/microbe has no build for ${platform}: ${cause.message}`);
+    err.cause = cause;
     throw err;
   }
 }

napi/scripts/smoke.cjs

@@ -0,0 +1,13 @@
+// Loads the addon beside index.js and installs real packages with it, sync and async.
+// Run on a runner that can load the build, natively or inside a container.
+"use strict";
+const path = require("node:path");
+const { install, installSync } = require("../index.js");
+
+const dir = path.join(require("node:os").tmpdir(), "napi-smoke");
+const done = installSync(["is-odd@^3"], dir);
+if (done.roots[0].name !== "is-odd") throw new Error(JSON.stringify(done));
+install({ typescript: "5" }, dir).then((r) => {
+  if (!r.bins.tsc) throw new Error(JSON.stringify(r));
+  console.log(r.roots.map((x) => x.name + "@" + x.version).join(" "), Object.keys(r.bins));
+});