Redis cluster demo example

yolo_redis.ts

import {spawn} from 'child_process';
import fs from 'fs';
import os from 'os';

function mkConfigs(port: number) {
  return `
bind 127.0.0.1
port ${port}
cluster-enabled yes
cluster-config-file nodes-${port}.conf
cluster-node-timeout 5000
  `;
}

async function runCluster(ports: [number, number, number]) {
  const baseDir = fs.mkdtempSync(`${os.tmpdir()}/redis-cluster-`);

  const procs = ports.map(port => {
    const configFile = `${baseDir}/config-${port}`;
    fs.writeFileSync(configFile, mkConfigs(port));
    return spawn('redis-server', [configFile], {cwd: baseDir});
  });

  const createArgs = ['--cluster', 'create', ...ports.map(port => `127.0.0.1:${port}`)];
  const cli = spawn('redis-cli', createArgs, {stdio: 'pipe'});
  cli.stdin.write('yes\n');

  const res = await new Promise(r => cli.once('exit', r));
  if (res !== 0)
    throw new Error(`Unable to start a new cluster. Exit code: ${res}`);

  console.log(`Started cluster on ${ports.join(', ')}`);
  return procs;
}

async function script() {
  const yargs = await import('yargs');
  const {argv} = yargs
    .demandOption('yolo')
    .option('port', {
      alias: ['p', 'ports'],
      default: [6380, 6381, 6382],
      number: true,
      array: true,
    })
    .help();

  const procs = await runCluster(argv.ports);
  const serverDidExit = Promise.race(procs.map(p => new Promise(r => p.once('exit', r))));

  return Promise.race([
    serverDidExit.then(code => console.log('At least one redis server exited with code', code)),
    new Promise(r => process.once('SIGINT', r))
  ]);
}

if (require.main === module)
  script().then(() => {
    console.log('Done. Exiting.');
    process.exit(0);
  }, err => {
    console.error('Encountered Error:', err);
    process.exit(1);
  });