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cache-warmup

Module to execute warmup of the cache when app starts.

Installation​

By default, the module is already included in @tramvai/module-server and no additional actions are needed.

import { createApp } from '@tramvai/core';
import { CacheWarmupModule } from '@tramvai/module-cache-warmup';

createApp({
  modules: [CacheWarmupModule],
});

Explanation​

Module is executed only when NODE_ENV === production.

  1. When app starts the module will request list of app urls from papi-route prerenderRoutes.
  2. For every url from the response it sends two requests: one for mobile and one for desktop device. But only 1 requests are running simultaneously in total.
  3. Routes with dynamic parameters, like /blog/:id/, will be skipped by default

Routes with dynamic parameters​

For example, you want to warmp up dynamic routes like /blog/1/, /blog/2/ and /blog/3/. CacheWarmupModule will use the same urls list as tramvai static command, so you need to use the same mechanism - custom prerender:routes hook.

Filtering routes from warmup​

If you want to exclude some routes from warmup, you can use cache-warmup:request hook for CACHE_WARMUP_HOOKS_TOKEN token:

const provider = provide({
  provide: commandLineListTokens.listen,
  useFactory: ({ hooks, logger }) => {
    return async function filterWarmupRoutes() {
      hooks['cache-warmup:request'].wrap(async (_, payload, next) => {
        // Match request url or any other parameters, and skip it
        if (payload.parameters.url?.includes('/some-unpopular-and-heavy-page')) {
          return {
            parameters: payload.parameters,
            result: 'skipped',
          };
        }
        // Otherwise, continue with the request
        return next(payload);
      });
    };
  },
  deps: {
    hooks: CACHE_WARMUP_HOOKS_TOKEN,
    logger: LOGGER_TOKEN,
  },
});

User-agent​

In order to emulate mobile or desktop device next user-agent strings are used:

[
  /** Chrome on Mac OS */
  'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.87 Safari/537.36',
  /**  Chrome on Mobile */
  'Mozilla/5.0 (Linux; Android 7.0; SM-G930V Build/NRD90M) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.125 Mobile Safari/537.36',
];

Debug​

This module logs with id cache-warmup

How to​

How to disable cache warmup?​

Run application with env variable CACHE_WARMUP_DISABLED=true to prevent cache warmup in local or testing environments.