readme.md

Vercel Ignore Build Step Example

NOTE: I no longer use this script since the release of turbo-ignore (More details)

Example of a script called by vercel Ignored Build Step option to only build application in monorepo when changes have been detected.

---

node ../../scripts/ignore-step.js

More details available here

ignore-build-step-vercel.js

const childProcess = require("child_process");

// https://vercel.com/support/articles/how-do-i-use-the-ignored-build-step-field-on-vercel
const ABORT_BUILD_CODE = 0;
const CONTINUE_BUILD_CODE = 1;

const continueBuild = () => process.exit(CONTINUE_BUILD_CODE);
const abortBuild = () => process.exit(ABORT_BUILD_CODE);

const app = process.argv[2] || path.basename(path.resolve());

const stepCheck = () => {
  // no app name (directory) was passed in via args
  if (!app) {
    return abortBuild();
  }

  // get all file names changed in last commit
  const fileNameList = childProcess
    .execSync("git diff --name-only HEAD~1")
    .toString()
    .trim()
    .split("\n");

  // check if any files in the app, or in any shared packages have changed
  const shouldBuild = fileNameList.some(
    (file) => file.startsWith(`apps/${app}`) || file.startsWith("packages/")
  );

  if (shouldBuild) {
    return continueBuild();
  }

  return abortBuild();
};

stepCheck();

This modification checks against the previous successful deploy commit SHA, which is provided by vercel now. (https://vercel.com/docs/concepts/projects/environment-variables/system-environment-variables)

const fileNameList = childProcess
    .execSync(
      `git diff ${process.env.VERCEL_GIT_PREVIOUS_SHA} HEAD --name-only ./`
    )
    .toString()
    .trim()
    .split("\n");

Just wanted to say thank you!
and if you are using "type": "module", in your package.json file, then rename the file to ignore-step.cjs