Parsing the Markdown files in https://github.com/docker/docker.github.io to extract the redirect_from url's for use in DevDocs

redirects.js

const fs = require('fs');
const path = require('path');
const fg = require('fast-glob');
const fm = require('front-matter');

(async () => {
  const files = await fg('**/*.md');

  const redirects = {};

  for (const file of files) {
    const content = await fs.promises.readFile(file, 'utf-8');
    const data = fm(content);

    const redirectFrom = data.attributes.redirect_from;
    if (redirectFrom === undefined || redirectFrom === null) {
      continue;
    }

    const redirectTo = path.dirname(file);
    if (redirectTo.includes('.')) {
      continue;
    }

    const urls = Array.isArray(redirectFrom) ? redirectFrom : [redirectFrom];
    for (const url of urls) {
      const urlWithSlash = url.substring(1) + (url.endsWith('/') ? '' : '/');
      const urlWithoutSlash = urlWithSlash.substring(0, urlWithSlash.length - 1);

      if (urlWithSlash === redirectTo || urlWithoutSlash === redirectTo) {
        continue;
      }

      redirects[urlWithSlash] = redirectTo;
      redirects[urlWithoutSlash] = redirectTo;
    }
  }

  for (const url of Object.keys(redirects).sort().reverse()) {
    console.log(`'${url}' => '${redirects[url]}',`);
  }
})();