Function prepareCache

packages/container/src/prepare-cache.ts:26–53

(
  _options: PrepareCacheOptions
)

 * `VERCEL_VCR_DISABLE_LAYER_CACHE=1`.
 */
export async function prepareCache(
  _options: PrepareCacheOptions
): Promise<Files> {
  if (process.env.VERCEL_VCR_DISABLE_LAYER_CACHE) {
    debug('layer cache disabled (VERCEL_VCR_DISABLE_LAYER_CACHE)');
    return {};
  }

  // The buildah store only exists in the build container.
  if (!isBuildContainer()) {
    debug('skipping container layer cache (not in build container)');
    return {};
  }

  if (!existsSync(BUILDAH_GRAPH_ROOT)) {
    debug(`no buildah store to cache at ${BUILDAH_GRAPH_ROOT}`);
    return {};
  }

  const start = Date.now();
  const files = await glob(`${GRAPH_ROOT_REL}/**`, CACHE_ROOT);
  const count = Object.keys(files).length;
  info(
    `cached container layer store: ${count} files from ${BUILDAH_GRAPH_ROOT} ` +
      `in ${Date.now() - start}ms`
  );
  return files;
}