Create a ok route

[benoitvidis]

We need a basic healthcheck route to monitor a kuzzle node.

[jenow]

Can't we use the "now" route for this? If yes we should modify the route for it to be called without any rights

[AnthonySendra]

@benoitvidis ?

[ballinette]

Sample code:

 healthCheckAction (request) {
    const
      kuzzle = this.context.accessors.kuzzle;

    return kuzzle.services.list.memoryStorage.info()
      .then(() => kuzzle.services.list.storageEngine.client.cluster.health())
      .then(response => {
        if (['yellow', 'green'].indexOf(response.status) < 0) {
          return Promise.reject(new Error('es is down: ' + JSON.stringify(response)));
        }
        return response;
      })
      .then(() => {
        request.setResult('ok', {
          status: 200,
          headers: {
            'Cache-control': 'no-cache',
            Pragma: 'no-cache'
          },
          raw: request.context.protocol === 'http'
        });

        return 'ok';
      })
      .catch(err => {
        this.context.log.error('[health check] ' + err.stack);

        request.setResult('ko', {
          status: 503,
          headers: {
            'Cache-control': 'no-cache',
            Pragma: 'no-cache'
          },
          raw: request.context.protocol === 'http'
        });

        return 'ko';
      });

  }