Lambda

I believe in learn by doing these days. In order to create a real world node.js application. I decided to go through most key features of node by creating a bunch of aws nodejs serverless lambda functions as a warm-up.

Lambda and Node, one stone two bird.

Here comes the every steps...

Serverless.com

Let's start with serverless, a framework that shows up a lot at egghead.

As to me I think it make sense to maintain the serverless function in serverless way. Just in case one day I will move it from aws to other cloud provider.

• Template

You can start with a template as boilerplate by command line.

serverless create -t [template name] -p [service name]

However I have to begin with examples due to some annoying issue that my default local serverless provider issue. 😡

Step 1: A json crud service

• Firstly I want to create a service that I could CRUD a json object. Based on which a number of biz api shall be built.

  So we have 2 todos as below.

  • a serverless function CRUD a javascript object.
  • a S3 bucket hold on the json file.

• Start with aws-node-fetch-file-and-store-in-s3 template

  • give it a test and it works like a charm

  TIP

  You have to create a s3 bucket beforehand and update yml file accordingly

  custom:
    bucket: [bucket name]
  

  also IAM Role Permission have to be put in the config file either.

  provider:
    name: aws
    runtime: nodejs14.x
    stage: dev
    iam:
      role:
        statements:
          - Effect: Allow
            Action:
              - s3:GetObject
              - s3:GetObjectAcl
              - s3:PutObject
              - s3:PutObjectAcl
            Resource: "arn:aws:s3:::${self:custom.bucket}/*"
  

  • refer to commit

• The crud service

  • lowdb

  I don't want to use any database yet since learning Node is why all it happens in the first place. A Json file hold on the entire application data should suffice. I assumed.

  Besides I don't want to reinvent the wheel. After awhile I found this nice JSON database lib.

  lowdb only support ESM, so I have to alter the template accordingly. Pls refer to source code

  • adaptor

  There is no built-in s3 adaptor expect for 3rd party one lowdb-adapter-aws-s3.

  I dived into the source code and found out that it may not meed my requirement sooner or later. So I decided to create it on my own.

  see the source code of s3Adaptor.js