NodeJS Lambda with DynamoDB setup for dev environment

app.js

const AWS = require('aws-sdk')

const IS_OFFLINE = process.env.NODE_ENV !== 'production'

let options = {}

// connect to local DB if running offline
if (IS_OFFLINE) {
  const DYNAMO_ENDPOINT = process.env.DYNAMO_ENDPOINT
  options = {
    region: 'localhost',
    endpoint: DYNAMO_ENDPOINT,
    accessKeyId: 'DEFAULT_ACCESS_KEY',
    secretAccessKey: 'DEFAULT_SECRET'
  }
}

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

dynamoDb.scan(params, (error, result) => {
  if (error) {
    return { error: 'Error fetching notifications' }
  }

  return result.Items
})

docker-compose.yaml

version: "3"
services:
  dynamo:
    image: "amazon/dynamodb-local:latest"
    command: ["-jar", "DynamoDBLocal.jar", "-sharedDb", "-inMemory"]
    ports:
      - "8000:8000"
  lambda:
    image: "node:10-alpine"
    user: node
    working_dir: /home/node/app
    command: npm run dev
    environment:
      DYNAMO_ENDPOINT: http://dynamo:8000

      # Note: even though these keys are garbage values, access key and
      # secret key are still required. Otherwise, `aws-sdk` will attempt
      # to read credentials from Amazon's `169.254.169.254` service and
      # fail.
      AWS_ACCESS_KEY_ID: "abc"
      AWS_SECRET_ACCESS_KEY: "xyz"
      AWS_REGION: "us-east-1"
    depends_on:
      - dynamo
    volumes:
      - .:/home/node/app
    ports:
      - "3000:3000"

package.json

  "scripts": {
    "dev": "nodemon local.js"
  },

start-dev.sh

#!/bin/bash
set -e

# Launch docker containers
docker-compose up -d

# Create notifications table
aws dynamodb create-table --cli-input-json file://table-model.json --endpoint-url http://localhost:8000

table-model.json

{
    "TableName": "notifications",
    "KeySchema": [
        {
            "AttributeName": "id",
            "KeyType": "HASH"
        }
    ],
    "AttributeDefinitions": [
        {
            "AttributeName": "id",
            "AttributeType": "S"
        }
    ],
    "ProvisionedThroughput": {
        "ReadCapacityUnits": 1,
        "WriteCapacityUnits": 1
    }
}

Run ./start-dev.sh to get going