Add experimental turbo-ignore package (vercel#1154)

This package can be used to automatically cancel irrelevant builds on Vercel via Ignored Build Step Command

packages/turbo-ignore/index.js

@@ -0,0 +1,101 @@
+#!/usr/bin/env node
+
+const { exec } = require("child_process");
+const fs = require("fs");
+const path = require("path");
+const { findRootSync } = require("@manypkg/find-root");
+
+console.log(
+  "≫ Using Turborepo to determine if this project is affected by the commit..."
+);
+const root = getRoot();
+const scope = getScope();
+const command = `npx turbo run build --filter=${scope}...[HEAD^] --dry=json`;
+console.log(`≫ Analyzing results of \`${command}\`...`);
+exec(
+  command,
+  {
+    cwd: root,
+  },
+  (error, stdout, stderr) => {
+    if (error) {
+      console.error(`exec error: ${error}`);
+      return;
+    }
+
+    try {
+      const parsed = JSON.parse(stdout);
+      if (parsed == null) {
+        console.error(`≫ Failed to parse JSON output from \`${command}\`.`);
+        console.error(`≫ Proceeding with build to be safe...`);
+        process.exit(1);
+      }
+      const { packages } = parsed;
+      if (packages && packages.length > 0) {
+        console.log(
+          `≫ The commit affects this project and/or its ${
+            packages.length - 1
+          } dependencies`
+        );
+        console.log(`≫ Proceeding with build...`);
+        process.exit(1);
+      } else {
+        console.log("≫ This project and its dependencies are not affected");
+        console.log("≫ Ignoring the change");
+        process.exit(0);
+      }
+    } catch (e) {
+      console.error(`≫ Failed to parse JSON output from \`${command}\`.`);
+      console.error(e);
+      console.error(`≫ Proceeding with build to be safe...`);
+      process.exit(1);
+    }
+  }
+);
+
+function searchUp(pathName, cwd) {
+  const root = path.parse(cwd).root;
+
+  let found = false;
+
+  while (!found && cwd !== root) {
+    if (fs.existsSync(path.join(cwd, pathName))) {
+      found = true;
+      break;
+    }
+
+    cwd = path.dirname(cwd);
+  }
+
+  if (found) {
+    return cwd;
+  }
+
+  return null;
+}
+
+function getScope() {
+  if (process.argv.length > 1 && process.argv[2] != null) {
+    return process.argv[2];
+  }
+  const raw = fs.readFileSync(path.join(process.cwd(), "package.json"), "utf8");
+  const pkgJSON = JSON.parse(raw);
+  console.log(`≫ Inferred \`${pkgJSON.name}\` as scope from "./package.json"`);
+  return pkgJSON.name;
+}
+
+function getRoot() {
+  let root = searchUp("turbo.json", process.cwd());
+
+  if (!root) {
+    root = findRootSync(process.cwd());
+    if (!root) {
+      console.error(
+        "Error: workspace root not found. turbo-ignore inferencing failed, proceeding with build."
+      );
+      console.error("");
+      process.exit(1);
+    }
+  }
+  return root;
+}

packages/turbo-ignore/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "turbo-ignore",
+  "version": "0.0.39",
+  "description": "",
+  "main": "index.js",
+  "bin": "index.js",
+  "keywords": [],
+  "author": "Jared Palmer",
+  "license": "MPL-2.0",
+  "scripts": {
+    "build": "tsup index.js --format=cjs && cp ./package.json ./dist/package.json",
+    "release": "pnpm build && cd dist && npm publish"
+  },
+  "devDependencies": {
+    "@manypkg/find-root": "^1.1.0",
+    "esbuild": "^0.14.38",
+    "tsup": "^5.12.1"
+  }
+}