docker-ms/microservice-module-util-js

Module util.

Description

• This module is for keeping those very common, none business logic related util methods.

Note

1. Since it seems bitbucket branch tag doesn't work for npm install, so we use master branch.

Memo

/*
 * Basically this function done the wrap job for Node.js async lib -> 'parallel' kinds API, more details can refer here:
 *   http://www.sebastianseilund.com/nodejs-async-in-practice
 * 
 * gprc hasn't support 'Promise' yet, and the api also cannot be promisified, so I fall back to async, sad!
 *
 */
static funcWrapperForAsync(func) {
  if (!func || typeof func !== 'function') {
    throw new Error('Parameter must be a function.');
  }
  return (callback) => {
    func.call(arguments, (err, res) => {
      if (err) {
        return callback(err);
      }
      return callback(null, res);
    });
  };
}


/*
 * Service id format:
 *   serviceTag+pid+localIp:port
 */
static generateServiceId(serviceTag, pid, port) {
  if (!serviceTag || typeof serviceTag !== 'string' || serviceTag.trim().length === 0) {
    throw new Error('Invalid service tag provided.');
  }
  if (!Number.isInteger(pid) || !Number.isInteger(port) || pid < 0 || port < 0) {
    throw new Error('Invalid pid or port number provided.');
  }
  return this.getLocalIp().spread((address, family) => {
    return serviceTag + '+' + pid + '+' + address + ':' + port;
  });
}

static registerToConsul(consulAgent, serviceTag, pid, port, checks) {
  Promise.join(this.getLocalIp(), this.generateServiceId(serviceTag, pid, port), (ipInfo, serviceId) => {
    const _registerToConsul = () => {
      return consulAgent.agent.service.register({
        name: serviceId,
        id: serviceId,
        tags: [serviceTag, require('os').hostname()],
        address: ipInfo[0],
        port: port,
        checks: checks
      }).catch((err) => {
        return Promise.reject(err);
      });
    };

    setTimeout(() => {
      retry(_registerToConsul, {
        interval: 100,
        max_tries: 65535
      });
    }, Math.random() * 1000);
  });
}

static queryServiceByTag(consulAgent, serviceTagArr) {

  return consulAgent.catalog.service.list().then((res) => {

    const serviceGroupedByTag = serviceTagArr.reduce((acc, curr) => {
      acc[curr] = [];
      return acc;
    }, {});

    return Object.keys(res).reduce((acc, curr) => {
      const intersection = res[curr].filter((item) => {
        return serviceTagArr.indexOf(item) !== -1;
      });
      if (intersection.length) {
        acc[intersection[0]].push(curr);
      }
      return acc;
    }, serviceGroupedByTag);

  });

}

static getLocalIp() {
  return Promise.promisify(require('dns').lookup, {multiArgs: true})(require('os').hostname());
}