Next.js custom cache-handler.js for GCP Storage

cache-handler.js

const { CacheHandler } = require('@neshca/cache-handler');
const { Storage } = require('@google-cloud/storage');

const CACHE_PREFIX = 'cache-';
const ENV = process.env.NEXT_ENV || 'dev';
const CACHE_BUCKET_NAME = `your-bucket-${ENV}`;

CacheHandler.onCreation(async (params) => {
  const buildId = params.buildId || 'dev';
  const storageBucket = CACHE_BUCKET_NAME;
  const prefix = CACHE_PREFIX + buildId;
  const cacheExtension = 'json';

  const gcpStorage = new Storage();

  const bucket = gcpStorage.bucket(storageBucket);

  const handler = {
    async get(key) {
      console.log('Getting cache', key);
      if (!bucket) {
        console.error('Bucket not found');
        console.error(CACHE_BUCKET_NAME, GCP_PROJECT_ID);
        return null;
      }

      const contents = await bucket.file(`${prefix}-${key}.${cacheExtension}`).download();

      if (!contents) {
        return null;
      }

      console.log('Cache found', key);
      return JSON.parse(contents.toString());
    },

    async set(key, value) {
      console.log('Setting cache', key);
      const file_key = `${prefix}-${key}.${cacheExtension}`;
      const tags = value?.tags;
      const expireAt = value.lifespan.expireAt;
      const cacheValue = value;

      const customMetadata = {
        tags: JSON.stringify(tags),
      }

      await bucket.file(file_key).save(JSON.stringify(cacheValue), {
        contentType: 'application/json',
        gzip: true,
        metadata: {
          cacheControl: `max-age=${Math.floor(expireAt - Date.now() / 1000)}`,
          contentType: 'application/json',
          metadata: customMetadata,
        },
      });
    },

    async revalidateTag(tag) {
      const [files] = await bucket.getFiles();
      const deleteKeys = [];

      for (const file of files) {
        const [metadata] = await file?.getMetadata();
        const fileMetadata = metadata.metadata;

        let metaDataTags = [];
        if (fileMetadata?.tags && typeof fileMetadata?.tags === 'string') {
          metaDataTags = JSON.parse(fileMetadata.tags);
        }

        if (metaDataTags.includes(tag)) {
          deleteKeys.push(file.name);
        }
      }

      await Promise.all(deleteKeys.map((key) => bucket.file(key).delete()));
    },
  };

  return {
    handlers: [handler],
  };
});

module.exports = CacheHandler;