systemic-service-runner/index.js

Starts systemic systems

const duration = require('parse-duration');
const format = require('util').format;
const signals = ['SIGINT', 'SIGTERM'];

module.exports = (system, options = {}) => {
  if (!system) throw new Error('system is required');

  const config = Object.assign({ restart: { window: '60s' } }, options);
  const logger = options.logger || console;
  let timeout;

  const start = (cb) => {
    system.start((err, components) => {
      if (err) return cb(err);

      const scheduleRestart = () => {
        const delay = Math.ceil((Math.random() * duration(config.restart.window)) / 1000) * 1000;
        logger.info(format('Service will restart in %s seconds.', delay / 1000));

        clearTimeout(timeout);
        timeout = setTimeout(() => {
          system.restart((err) => {
            if (err) {
              logger.error('Error restarting system.');
              logger.error(err);
              process.exit(1);
            }
          });
        }, delay);
        timeout.unref();
      };

      process.on('systemic_restart', scheduleRestart);

      process.on('error', (err) => {
        logger.error('Unhandled error. Invoking shutdown.');
        if (err) logger.error(err.stack);
        system.stop(() => process.exit(1));
      });

      process.on('unhandledRejection', (err) => {
        logger.error('Unhandled rejection. Invoking shutdown.');
        if (err) logger.error(err.stack);
        system.stop(() => process.exit(1));
      });

      signals.forEach((signal) => {
        process.on(signal, () => {
          logger.info(format('Received %s. Attempting to shutdown gracefully.', signal));
          system.stop(() => process.exit(0));
        });
      });

      cb(null, components);
    });
  };

  const stop = (cb) => system.stop(cb);

  return {
    start,
    stop,
  };
};