next-impl-cache-adapter

An adapter that allows you to use any cache handler on the client and server side and switch between them. Adds support for running next.js applications in multiple instances.

Installation

Using npm:

npm i next-impl-cache-adapter

Using yarn:

yarn add next-impl-cache-adapter

How it works

For a common cache between instances (replicas, copies) - the cache should be separate from each application instance. This solution does it by creating a separate service.

The application can then work with the cache through this remote server. The server acts as a cacheHandler and can be used from the running application and/or from the build mode.

The server does not need to be restarted each time. And outdated data will be deleted automatically when launching a new version of the application.

Usage

The server is launched, to which the required cacheHandler is passed:

// @ts-check

const createServer = require('next-impl-cache-adapter/src/create-server');
const CacheHandler = require('next-impl-cache-in-memory');

const server = createServer(new CacheHandler({}));

server.listen('4000', () => {
    console.log('Server is running at http://localhost:4000');
});

A special adapter is set up to work with the cache:

// cache-handler.js
// @ts-check
const AppAdapter = require('next-impl-cache-adapter');
const CacheHandler = require('next-impl-cache-in-memory');

class CustomCacheHandler extends AppAdapter {
    /** @param {any} options */
    constructor(options) {
        super({
            CacheHandler,
            buildId: process.env.BUILD_ID || 'base_id',
            cacheUrl: 'http://localhost:4000',
            cacheMode: 'remote',
            options,
        })
    }
}

module.exports = CustomCacheHandler;

The created cache-handler is connected in the next.js configuration:

// next.config.js

module.exports = {
  cacheHandler: require.resolve('./cache-handler.js'),
  cacheMaxMemorySize: 0, // disable default in-memory caching
}

That's it. Now the cache is configured.

Configuration

CacheHandler

CacheHandler, which will be responsible for the logic of caching.

buildId

A unique id of the current build. It should be same between instances. When launching an application with a new id, the cache for old ids will be deleted.

cacheUrl

A url where the remote cache is running.

cacheMode

The package supports three caching modes: local, remote and isomorphic.

local

A standard solution, the cache is processed next to the application. Convenient to use in development mode and on stages where the application is run in a single instance.

remote

All cache will be written and read on a remote server, launched earlier. Convenient to use for applications running in multiple replicas.

isomorphic

The cache operates next to the application, but additionally stores data on a remote server. Convenient to use during the build, to prepare the cache by the time the application instances are launched, but without spending resources on loading the cache from a remote server.

options

Options passed to cacheHandler from next.js. They just need to be passed from the argument.

Examples

Base example with next-impl-cache-in-memory. See example.

License

MIT