How to import third-party libraries for Node runtime

Statement:

• The operating system as mentioned in this document is Ubuntu16.04.
• The version of runtime is Node8.5
• The MQTT client toolkit as mentioned in this document is MQTTBox.
• In this document, we give an example about how import the third-party library Lodash.
• In this article, the service created based on the Hub module is called localhub service. And for the test case mentioned here, the localhub service, function calculation service, and other services are configured as follows:

# The configuration of Local Hub service
# Configuration file location is: var/db/baetyl/localhub-conf/service.yml
listen:
  - tcp://0.0.0.0:1883
principals:
  - username: 'test'
    password: 'hahaha'
    permissions:
      - action: 'pub'
        permit: ['#']
      - action: 'sub'
        permit: ['#']

# The configuration of Local Function Manager service
# Configuration file location is: var/db/baetyl/function-manager-conf/service.yml
hub:
  address: tcp://localhub:1883
  username: test
  password: hahaha
rules:
  - clientid: localfunc-1
    subscribe:
      topic: node
    function:
      name: sayhi
    publish:
      topic: t/hi
functions:
  - name: sayhi
    service: function-sayhi
    instance:
      min: 0
      max: 10
      idletime: 1m

# The configuration of application.yml
# Configuration file location is: var/db/baetyl/application.yml
version: v0
services:
  - name: localhub
    image: hub.baidubce.com/baetyl/baetyl-hub
    replica: 1
    ports:
      - 1883:1883
    mounts:
      - name: localhub-conf
        path: etc/baetyl
        readonly: true
      - name: localhub-data
        path: var/db/baetyl/data
      - name: localhub-log
        path: var/log/baetyl
  - name: function-manager
    image: hub.baidubce.com/baetyl/baetyl-function-manager
    replica: 1
    mounts:
      - name: function-manager-conf
        path: etc/baetyl
        readonly: true
      - name: function-manager-log
        path: var/log/baetyl
  - name: function-sayhi
    image: hub.baidubce.com/baetyl/baetyl-function-node85
    replica: 0
    mounts:
      - name: function-sayjs-conf
        path: etc/baetyl
        readonly: true
      - name: function-sayjs-code
        path: var/db/baetyl/function-sayhi
        readonly: true
volumes:
  # hub
  - name: localhub-conf
    path: var/db/baetyl/localhub-conf
  - name: localhub-data
    path: var/db/baetyl/localhub-data
  - name: localhub-log
    path: var/db/baetyl/localhub-log
  # function manager
  - name: function-manager-conf
    path: var/db/baetyl/function-manager-conf
  - name: function-manager-log
    path: var/db/baetyl/function-manager-log
  # function node runtime sayhi
  - name: function-sayjs-conf
    path: var/db/baetyl/function-sayjs-conf
  - name: function-sayjs-code
    path: var/db/baetyl/function-sayjs-code

Generally, using the Node Standard Library may not meet our needs. In fact, it is often necessary to import some third-party libraries. We’ll give one example below.

Import Lodash third-party libraries

Lodash is a modern JavaScript utility library delivering modularity, performance & extras. Baetyl support import third-party libraries such as Lodash to use its functions. How to import it, as shown below:

• Step 1: change path to the directory of javascripts, then install Lodash package

cd /directory/of/Node/script
npm install --save lodash

• Step 2: import Lodash in a javascript:

const _ = require('lodash');

• Step 3: execute your javascript:

node your_script.js

If the above operations are normal, the resulting script directory structure is as shown in the following figure.

the directory of Lodash

Now we write the script index.js to use functions provided by Lodash. More detailed contents are as follows:

#!/usr/bin/env node

const _ = require('lodash');

exports.handler = (event, context, callback) => {
  result = {}
  
  //remove repeating elements in array
  result["unique_array"] = _.uniq(event['array']);
  //sort
  result['sorted_users'] = _.sortBy(event['users'], function(o) { return o.age; });
  //filter
  result['filtered_users'] = _.filter(event['users'], function(o) { return !o.active; });

  callback(null, result);
}

The configuration of Node function runtime is as below:

# The configuration of Node function runtime
functions:
  - name: 'sayhi'
    handler: 'index.handler'
    codedir: 'var/db/baetyl/function-sayhi'

First define the following json data as an input message:

{
    "array": ["Jane", 1, "Jane", 1, 2],
    "users": [
        { "user": "barney", "age": 36, "active": true  },
        { "user": "fred",   "age": 40, "active": false },
        { "user": "Jane",   "age": 32, "active": true  }
    ]
}

As above, after the localhub service receives the message sent to the topic node, it calls index.js script to execute the concrete logic to remove repeated elements, filter, sort of array in input data. The result is then fed back to the topic t/hi as an MQTT message. We subscribe to the topic t/hi via MQTTBox and we can observe the following message:

{
    "unique_array": ["Jane", 1, 2],
    "sorted_users": [
        { "user": "Jane",   "age": 32, "active": true  },
        { 'user': 'barney', "age": 36, "active": true  },
        { "user": "fred",   "age": 40, "active": false }
    ],
    "filtered_users": [
        { "user": "fred",   "age": 40, "active": false }
    ],
}

using_lodash