Function runSync

packages/python/src/start-dev-server.ts:226–310

({
  manifestType,
  manifestPath,
  uvPath,
  pythonBin,
  env,
  onStdout,
  onStderr,
}: RunSyncOptions)

}

async function runSync({
  manifestType,
  manifestPath,
  uvPath,
  pythonBin,
  env,
  onStdout,
  onStderr,
}: RunSyncOptions): Promise<void> {
  const projectDir = dirname(manifestPath);

  const pip = uvPath
    ? { cmd: uvPath, prefix: ['pip', 'install'] }
    : { cmd: pythonBin, prefix: ['-m', 'pip', 'install'] };

  let spawnCmd: string;
  let spawnArgs: string[];

  switch (manifestType) {
    case 'uv.lock': {
      if (!uvPath) {
        throw new NowBuildError({
          code: 'PYTHON_DEPENDENCY_SYNC_FAILED',
          message: 'uv is required to install dependencies from uv.lock.',
          link: 'https://docs.astral.sh/uv/getting-started/installation/',
          action: 'Install uv',
        });
      }
      spawnCmd = uvPath;
      spawnArgs = ['sync'];
      break;
    }
    case 'pylock.toml': {
      spawnCmd = pip.cmd;
      spawnArgs = [...pip.prefix, '-r', manifestPath];
      break;
    }
    case 'pyproject.toml': {
      spawnCmd = pip.cmd;
      spawnArgs = [...pip.prefix, projectDir];
      break;
    }
    default:
      debug(`Unknown manifest type: ${manifestType}`);
      return;
  }

  await new Promise<void>((resolve, reject) => {
    debug(`Running "${spawnCmd} ${spawnArgs.join(' ')}" in ${projectDir}...`);
    const child = spawn(spawnCmd, spawnArgs, {
      cwd: projectDir,
      env: getProtectedUvEnv(env),
      stdio: ['inherit', 'pipe', 'pipe'],
    });

    child.stdout?.on('data', (data: Buffer) => {
      if (onStdout) {
        onStdout(data);