Function createBuildProcess

packages/cli/src/util/dev/builder.ts:171–217

(
  match: BuildMatch,
  envConfigs: EnvConfigs,
  workPath: string
)

}

async function createBuildProcess(
  match: BuildMatch,
  envConfigs: EnvConfigs,
  workPath: string
): Promise<ChildProcess> {
  output.debug(`Creating build process for "${match.entrypoint}"`);

  const builderWorkerPath = join(__dirname, 'builder-worker.cjs');

  // Ensure that `node` is in the builder's `PATH`
  const PATH = `${dirname(process.execPath)}${delimiter}${process.env.PATH}`;

  const env: Env = {
    ...process.env,
    PATH,
    ...envConfigs.allEnv,
  };

  const buildProcess = fork(builderWorkerPath, [], {
    cwd: workPath,
    execArgv: [],
    env,
  });
  match.buildProcess = buildProcess;

  buildProcess.on('close', (code, signal) => {
    output.debug(
      `Build process for "${match.entrypoint}" exited with ${signal || code}`
    );
    match.buildProcess = undefined;
  });

  return new Promise((resolve, reject) => {
    // The first message that the builder process sends is the `ready` event
    buildProcess.once('message', data => {
      if (
        data !== null &&
        typeof data === 'object' &&
        (data as { type: string }).type !== 'ready'
      ) {
        reject(new Error('Did not get "ready" event from builder'));
      } else {
        resolve(buildProcess);
      }
    });
  });
}

export async function executeBuild(
  vercelConfig: VercelConfig,