serverless.yaml

provider:
  name: aws
  runtime: nodejs12.x
  environment:
    USER_TABLE: ${self:service}-${opt-stage, self:provider.stage}
    USER_EMAIL_TABLE: "user-email-${opt:stage, self:provider.stage}"
  iamRoleStatements:
    - Effect: Allow
      Action:
        - dynamodb:Query
        - dynamodb:Scan
        - dynamodb:GetItem
        - dynamodb:PutItem
      Resource: "*"
resources:
  Resources:
    UsersDynamoDbTable:
      Type: "AWS::DynamoDB::Table"
      DeletionPolicy: Retain
      Properties:
        AttributeDefinitions:
          - AttributeName: "id"
            AttributeType: "S"
        KeySchema:
          - AttributeName: "id"
            KeyType: "HASH"
        ProvisionedThroughput:
          ReadCapacityUnits: 1
          WriteCapacityUnits: 1
        StreamSpecification:
          StreamViewType: "NEW_AND_OLD_IMAGES"
        TableName: ${self:provider.environment.USER_TABLE}
functions:
  createUser:
    handler: user.create
    memorySize: 128
    description: Creation of a new user account
    events:
      - http:
          path: users
          method: post

user.js

'use strict';

const uuid = require('uuid');
const AWS = require('aws-sdk');

AWS.config.setPromisesDependency(require('bluebird'));

const dynamoDb = new AWS.DynamoDB.DocumentClient();

module.exports.create = async (event, context, callback) => {
  const requestBody = JSON.parse(event.body);
  const fullname = requestBody.fullname;
  const email = requestBody.email;

  if (typeof fullname !== 'string' || typeof email !== 'string') {
    console.error('Validation Failed');
    callback(new Error('Couldn\'t submit candidate because of validation errors.'));
    return;
  }

  submitCandidateP(candidateInfo(fullname, email))
    .then(res => {
      callback(null, {
        statusCode: 200,
        body: JSON.stringify({
          message: `Sucessfully submitted candidate with email ${email}`,
          candidateId: res.id
        })
      });
    })
    .catch(err => {
      console.log(err);
      callback(null, {
        statusCode: 500,
        body: JSON.stringify({
          message: `Unable to submit candidate with email ${email}`
        })
      })
    });
};

const submitCandidateP = candidate => {
  console.log('Submitting candidate to:', process.env.USER_TABLE);

  const candidateInfo = {
    TableName: process.env.USER_TABLE,
    Item: candidate,
  };

  console.log(candidateInfo);

  return dynamoDb.put(candidateInfo).promise()
    .catch(err => console.log(err))
    .then(res => candidate);
};

const candidateInfo = (fullname, email) => {
  const timestamp = new Date().getTime();
  return {
    id: uuid.v1(),
    fullname: fullname,
    email: email,
    submittedAt: timestamp,
    updatedAt: timestamp,
  };
};