feat(rollup): add support for generating build meta

README.md

@@ -27,6 +27,10 @@ Stub `dist` once using [jiti](https://github.com/unjs/jiti) and you can try and
 
 Integration with [untyped](https://github.com/unjs/untyped).
 
+### 📊 Analyze bundle size
+
+Generate rollup build metadata in JSON format to visualize with [Bundle Buddy](https://www.bundle-buddy.com).
+
 ### ✔️ Secure builds
 
 Automatically check for various build issues such as potential **missing** and **unused** [dependencies](https://docs.npmjs.com/cli/v7/configuring-npm/package-json#dependencies) and fail CI.

src/build.ts

@@ -98,6 +98,7 @@ async function _build(
       replace: {},
       failOnWarn: true,
       sourcemap: false,
+      metafile: false,
       rollup: {
         emitCJS: false,
         cjsBridge: false,

src/builder/plugins/metafile.ts

@@ -0,0 +1,41 @@
+import { writeFile } from "node:fs/promises";
+import type { Plugin } from "rollup";
+import { resolve } from "pathe";
+
+export interface MetafileOptions {
+  rootDir: string;
+  outDir: string;
+}
+
+export interface MetaInfo {
+  source: string;
+  target: string;
+}
+
+export function metafilePlugin(opts: MetafileOptions): Plugin {
+  return {
+    name: "unbuild:metafile",
+    async buildEnd() {
+      const deps: MetaInfo[] = [];
+
+      for (const id of this.getModuleIds()) {
+        const m = this.getModuleInfo(id);
+        if (m != null && !m.isExternal) {
+          for (const target of m.importedIds) {
+            deps.push({
+              source: id,
+              target,
+            });
+          }
+        }
+      }
+
+      if (Array.isArray(deps) && deps.length === 0) {
+        return;
+      }
+
+      const outPath = resolve(opts.outDir, `graph.json`);
+      await writeFile(outPath, JSON.stringify(deps, null, 2), "utf8");
+    },
+  } as Plugin;
+}

src/builder/rollup.ts

@@ -19,6 +19,7 @@ import { arrayIncludes, getpkg, tryResolve, warn } from "../utils";
 import type { BuildContext } from "../types";
 import { esbuild } from "./plugins/esbuild";
 import { JSONPlugin } from "./plugins/json";
+import { metafilePlugin } from "./plugins/metafile";
 import { rawPlugin } from "./plugins/raw";
 import { cjsPlugin } from "./plugins/cjs";
 import { shebangPlugin, makeExecutable, getShebang } from "./plugins/shebang";
@@ -187,6 +188,10 @@ export async function rollupBuild(ctx: BuildContext) {
 
     rollupOptions.plugins.push(dts(ctx.options.rollup.dts));
 
+    rollupOptions.plugins = rollupOptions.plugins.filter(
+      (p) => p.name !== "unbuild:metafile",
+    );
+
     await ctx.hooks.callHook("rollup:dts:options", ctx, rollupOptions);
     const typesBuild = await rollup(rollupOptions);
     await ctx.hooks.callHook("rollup:dts:build", ctx, typesBuild);
@@ -333,6 +338,12 @@ export function getRollupOptions(ctx: BuildContext): RollupOptions {
           ...ctx.options.rollup.json,
         }),
 
+      ctx.options.metafile &&
+        metafilePlugin({
+          rootDir: ctx.options.rootDir,
+          outDir: resolve(ctx.options.rootDir, ctx.options.outDir),
+        }),
+
       shebangPlugin(),
 
       ctx.options.rollup.esbuild &&

src/cli.ts

@@ -29,11 +29,16 @@ const main = defineCommand({
       type: "boolean",
       description: "Generate sourcemaps (experimental)",
     },
+    metafile: {
+      type: "boolean",
+      description: "Generate meta file (experimental)",
+    },
   },
   async run({ args }) {
     const rootDir = resolve(process.cwd(), args.dir || ".");
     await build(rootDir, args.stub, {
       sourcemap: args.sourcemap,
+      metafile: args.metafile,
       rollup: {
         esbuild: {
           minify: args.minify,

src/types.ts

@@ -66,6 +66,8 @@ export interface BuildOptions {
   clean: boolean;
   /** @experimental */
   sourcemap: boolean;
+  /** @experimental */
+  metafile: boolean;
   /**
    * * `compatible` means "src/index.ts" will generate "dist/index.d.mts", "dist/index.d.cts" and "dist/index.d.ts".
    * * `node16` means "src/index.ts" will generate "dist/index.d.mts" and "dist/index.d.cts".

test/fixture/build.config.ts

@@ -29,4 +29,12 @@ export default defineBuildConfig([
       },
     },
   },
+  // With sourcemaps and metafile
+  {
+    name: "metafile",
+    entries: ["src/index"],
+    outDir: "dist",
+    sourcemap: true,
+    metafile: true,
+  },
 ]);