How to cahce all pages with next.js

server.js

const express = require('express');
const next = require('next');
const LRUCache = require('lru-cache');

const port = parseInt(process.env.PORT, 10) || 3000;
const dev = process.env.NODE_ENV !== 'production';
const app = next({dev});
const handle = app.getRequestHandler();

// This is where we cache our rendered HTML pages
const ssrCache = new LRUCache({
    max: 100 * 1024 * 1024, /* cache size will be 100 MB using `return n.length` as length() function */
    length: function (n, key) {
        return n.length
    },
    maxAge: 1000 * 60 * 60 * 24 * 30
});

app.prepare()
    .then(() => {
        const server = express();

        server.get('/_next/*', (req, res) => {
            /* serving _next static content using next.js handler */
            handle(req, res);
        });

        server.get('*', (req, res) => {
            /* serving page */
            return renderAndCache(req, res)
        });

        /* starting server */
        server.listen(port, (err) => {
            if (err) throw err;
            console.log(`> Ready on http://localhost:${port}`)
        })
    });

/*
 * NB: make sure to modify this to take into account anything that should trigger
 * an immediate page change (e.g a locale stored in req.session)
 */
function getCacheKey(req) {
    return `${req.path}`
}

async function renderAndCache(req, res) {
    const key = getCacheKey(req);

    // If we have a page in the cache, let's serve it
    if (ssrCache.has(key)) {
        //console.log(`serving from cache ${key}`);
        res.setHeader('x-cache', 'HIT');
        res.send(ssrCache.get(key));
        return
    }

    try {
        //console.log(`key ${key} not found, rendering`);
        // If not let's render the page into HTML
        const html = await app.renderToHTML(req, res, req.path, req.query);

        // Something is wrong with the request, let's skip the cache
        if (res.statusCode !== 200) {
            res.send(html);
            return
        }

        // Let's cache this page
        ssrCache.set(key, html);

        res.setHeader('x-cache', 'MISS');
        res.send(html)
    } catch (err) {
        app.renderError(err, req, res, req.path, req.query)
    }
}