@arcblock/crawler

A crawler module designed for Blocklets. It supports batch crawling of HTML, webpage screenshots, title, description, and more, based on URL or Sitemap.

Usage

import { crawlUrl, getSnapshot, initCrawler } from '@arcblock/crawler';

await initCrawler();

// Asynchronously crawl a page
const jobId = await crawlUrl({ url: 'https://www.arcblock.io', includeScreenshot: true, includeHtml: true });

// Get the crawling result (need to wait for the crawler to finish)
const snapshot = await getSnapshot(jobId);

initCrawler

Initializes the crawler.

crawlUrl

Crawls the specified page.

getSnapshot

Gets the crawling result by jobId.

getLatestSnapshot

Gets the latest crawling result by URL.

Schedule

Passing siteCron to initCrawler will enable scheduled tasks to periodically crawl all pages of specified websites based on their sitemaps.

await initCrawler({
  siteCron: {
    enabled: !!env.preferences.cronEnabled,
    immediate: !!env.preferences.cronImmediate,
    sites: env.preferences.cronSites,
    time: env.preferences.cronTime,
    concurrency: env.preferences.concurrency,
  },
});

Environment Variables

• PUPPETEER_EXECUTABLE_PATH: The execution path for Puppeteer. This variable is not required if used within the arcblock/snap-kit Docker image. When developing locally, you can set it to the Chrome path: /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

If not referenced by a Blocklet, some dependent Blocklet environment variables need to be provided:

• BLOCKLET_CACHE_DIR: (Optional) The directory for automatic Puppeteer installation if PUPPETEER_EXECUTABLE_PATH is not provided. Defaults to process.cwd().

• BLOCKLET_APP_URL: (Optional) The domain prefix for screenshot. Defaults to /.

• BLOCKLET_DATA_DIR: (Required) The directory to save webpage screenshots and HTML source files obtained by the crawler.

• BLOCKLET_LOG_DIR: (Required) Directory path for storing @blocklet/logger logs

SQLite

When initCrawler is called, it attempts to create an SQLite database at BLOCKLET_DATA_DIR. This database is used to cache HTML content and screenshot. Please ensure that the deployment environment supports SQLite.