@apolitical/server/src/services/health.service.js

Node.js module to encapsulate Apolitical's express server setup

'use strict';

module.exports = ({ health, lru, config }) => {
  const { CACHE_OPTIONS } = config.SERVER;
  // Setup health checker
  const healthCheck = new health.HealthChecker();
  // Setup cache
  const cache = new lru(CACHE_OPTIONS);

  function buildCheckWithCache(key, check) {
    cache.clear();
    return async function () {
      const checked = cache.get(key);
      if (!checked) {
        await check();
        cache.set(key, true);
      }
    };
  }

  // function registerStartup(startup) {
  //   healthCheck.registerStartupCheck(new health.StartupCheck("Startup Check", startup));
  // }

  function healthEndpoint() {
    return health.HealthEndpoint(healthCheck);
  }

  function registerReadiness(readiness) {
    const readinessWithCache = buildCheckWithCache('readiness', readiness);
    healthCheck.registerReadinessCheck(new health.ReadinessCheck('Readiness Check', readinessWithCache));
  }

  function readinessEndpoint() {
    return health.ReadinessEndpoint(healthCheck);
  }

  function registerLiveness(liveness) {
    const livenessWithCache = buildCheckWithCache('liveness', liveness);
    healthCheck.registerLivenessCheck(new health.LivenessCheck('Liveness Check', livenessWithCache));
  }

  function livenessEndpoint() {
    return health.LivenessEndpoint(healthCheck);
  }

  function registerShutdown(shutdown) {
    healthCheck.registerShutdownCheck(new health.ShutdownCheck('Shutdown Check', shutdown));
  }

  return { healthEndpoint, readinessEndpoint, registerReadiness, registerLiveness, livenessEndpoint, registerShutdown };
};